CLASSES

Selective Serotonin Reuptake Inhibitor Antidepressants, SSRIs

BOXED WARNING

Fluoxetine is indicated for the treatment of major depressive disorder in adolescents and children 8 years of age and older and for the treatment of obsessive-compulsive disorder (OCD) in pediatric patients 7 years of age and older. The safety and effectiveness of fluoxetine in children less than 7 years of age have not been established. In a pooled analysis of placebo-controlled trials of antidepressants (n = 4,500 pediatrics and 77,000 adults), there was an increased risk for suicidal thoughts and behaviors in patients 24 years of age and younger receiving an antidepressant versus placebo, with considerable variation in the risk of suicidality among drugs. The difference in absolute risk of suicidal thoughts and behaviors across different indications was highest in those with major depression. No suicides occurred in any of the pediatric trials. Nevertheless, the need for an antidepressant in children, adolescents, or young adults for any use must be weighed against the risk of suicidality; it is unknown if this risk extends to long-term use. All patients should be monitored for symptom worsening or suicidality, especially at treatment initiation or after dose changes. Caregivers and/or patients should immediately notify the prescriber of changes in behavior or suicidal ideation. A change to the treatment regimen or discontinuation of fluoxetine may be necessary in patients with emerging suicidality or worsening depression. The potential for growth inhibition in pediatric patients should be monitored during SSRI therapy. Monitor height and weight periodically while the patient is receiving fluoxetine. Data are inadequate to determine whether the chronic use of SSRIs causes long-term growth inhibition; however, decreased weight gain has been observed in children and adolescents receiving SSRIs. The mechanism of growth inhibition in children may be due to the suppression of growth hormone secretion, which is known to occur in adults taking SSRIs.

DEA CLASS

Rx

DESCRIPTION

Oral selective serotonin reuptake inhibitor (SSRI) antidepressant
Indicated for depression, obsessive-compulsive disorder (OCD), panic disorder, bulimia nervosa, and premenstrual dysphoric disorder in adults; used for depression and OCD in pediatric patients
Increased risk of suicidality in pediatrics and young adults during treatment initiation

COMMON BRAND NAMES

Prozac, Prozac Weekly, Sarafem, Selfemra

HOW SUPPLIED

Fluoxetine/Fluoxetine Hydrochloride/Prozac Oral Sol: 5mL, 20mg
Fluoxetine/Fluoxetine Hydrochloride/Prozac Weekly Oral Cap DR Pellets: 90mg
Fluoxetine/Fluoxetine Hydrochloride/Prozac/Sarafem Oral Tab: 10mg, 20mg, 60mg
Fluoxetine/Fluoxetine Hydrochloride/Prozac/Sarafem/Selfemra Oral Cap: 10mg, 20mg, 40mg

DOSAGE & INDICATIONS

†Indicates off-label use

MAXIMUM DOSAGE

80 mg/day PO (immediate-release daily dose forms); 90 mg/week PO for once weekly formulation.

80 mg/day PO (immediate-release daily dose forms); 90 mg/week PO for once weekly formulation.

60 mg/day PO of conventional oral dosage forms; safety and efficacy not established for the once-weekly dosage form.

7 to 12 years: 60 mg/day PO. Do not use the once-weekly dosage form.
4 to 6 years: Safety and efficacy have not been established. Doses up to 0.6 mg/kg/day PO (Max: 60 mg/day) have been used off-label in children with selective mutism. Do not use the once-weekly dosage form.
2 to 3 years: Safety and efficacy have not been established. Doses up to 0.5 mg/kg/day PO (Max: 40 mg/day) have been used off-label in children with autism. Do not use the once-weekly dosage form.
1 year: Safety and efficacy have not been established.

Safety and efficacy have not been established.

Safety and efficacy have not been established.

DOSING CONSIDERATIONS

A lower or less frequent dose should be used in patients with liver disease; however, quantitative guidelines are not available.

CrCl < 10 mL/min: Higher concentrations of the metabolites of fluoxetine (e.g., norfluoxetine) may be present in patients with severe renal impairment; however, use of a lower or less frequent dose is not routinely necessary in renally impaired patients.
 
Intermittent hemodialysis:
In a study of adult patients on hemodialysis, the steady-state plasma concentrations of fluoxetine and its active metabolite norfluoxetine were comparable to those of patients with normal renal function during use of dosages of 20 mg/day PO for 2 months; there are no routine dosage adjustments recommended for patients receiving dialysis.

ADMINISTRATION

May be administered without regard to meals.

STORAGE

Generic:
- Protect from light
- Store at controlled room temperature (between 68 and 77 degrees F)
Prozac:
- Keep from freezing
- Protect from light
- Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
Prozac Weekly:
- Store at controlled room temperature (between 68 and 77 degrees F)
Sarafem:
- Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
Selfemra :
- Protect from light
- Store between 68 to 77 degrees F

CONTRAINDICATIONS / PRECAUTIONS

Fluoxetine is contraindicated in those patients with fluoxetine hypersensitivity or hypersensitivity to any of the formulation components.

Avoid abrupt discontinuation of any SSRI if possible. Gradual tapering is recommended during discontinuation of any SSRI to decrease or prevent the occurrence of potential withdrawal symptoms. However, withdrawal symptoms have been reported less frequently with long-acting SSRIs such as fluoxetine than short-acting SSRIs such as paroxetine. Symptoms associated with abrupt withdrawal of fluoxetine have included dysphoric mood, irritability, agitation, dizziness, paresthesias, and headache.

Fluoxetine should be used with caution in patients with a seizure disorder. Seizures have been reported rarely in patients taking fluoxetine; however, they have occurred primarily in cases of fluoxetine overdose. Fluoxetine's effects during electroconvulsive therapy (ECT) have not been evaluated in clinical studies to date. Some clinicians have reported that in rare instances ECT-induced seizures were prolonged in patients taking fluoxetine. A possible mechanism of seizure prolongation may be a lowering of the seizure threshold caused by high concentrations of fluoxetine or its active metabolite norfluoxetine.

Fluoxetine is indicated for the treatment of major depressive disorder in adolescents and children 8 years of age and older and for the treatment of obsessive-compulsive disorder (OCD) in pediatric patients 7 years of age and older. The safety and effectiveness of fluoxetine in children less than 7 years of age have not been established. In a pooled analysis of placebo-controlled trials of antidepressants (n = 4,500 pediatrics and 77,000 adults), there was an increased risk for suicidal thoughts and behaviors in patients 24 years of age and younger receiving an antidepressant versus placebo, with considerable variation in the risk of suicidality among drugs. The difference in absolute risk of suicidal thoughts and behaviors across different indications was highest in those with major depression. No suicides occurred in any of the pediatric trials. Nevertheless, the need for an antidepressant in children, adolescents, or young adults for any use must be weighed against the risk of suicidality; it is unknown if this risk extends to long-term use. All patients should be monitored for symptom worsening or suicidality, especially at treatment initiation or after dose changes. Caregivers and/or patients should immediately notify the prescriber of changes in behavior or suicidal ideation. A change to the treatment regimen or discontinuation of fluoxetine may be necessary in patients with emerging suicidality or worsening depression. The potential for growth inhibition in pediatric patients should be monitored during SSRI therapy. Monitor height and weight periodically while the patient is receiving fluoxetine. Data are inadequate to determine whether the chronic use of SSRIs causes long-term growth inhibition; however, decreased weight gain has been observed in children and adolescents receiving SSRIs. The mechanism of growth inhibition in children may be due to the suppression of growth hormone secretion, which is known to occur in adults taking SSRIs.

Fluoxetine is contraindicated for concomitant use in patients receiving MAOI therapy. At least 14 days should elapse between discontinuation of an MAOI intended to treat psychiatric disorders and initiation of therapy with fluoxetine. Conversely, at least 5 weeks should be allowed after stopping fluoxetine before starting an MAOI intended to treat psychiatric disorders. Starting fluoxetine in a patient who is being treated with MAOIs such as linezolid or intravenous methylene blue, which also have MAOI activity, is also contraindicated because of an increased risk of serotonin syndrome. Other medications when combined with fluoxetine may increase the risk for serotonin syndrome. Serotonin syndrome has been reported with SSRIs, including fluoxetine, both when taken alone, but especially when co-administered with other serotonergic agents including serotonin agonists (triptans), tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines, and St. John’s Wort. If such symptoms occur, discontinue fluoxetine and initiate supportive treatment. The prolonged half-life of fluoxetine should be taken into account when treating such reactions.

The use of antidepressants has been associated with the precipitation of mania or hypomania in susceptible individuals. If a patient develops manic symptoms, fluoxetine should be withheld, and appropriate therapy initiated to treat the manic symptoms. Depression may also be the presenting symptom of a mixed/manic episode of bipolar disorder. Patients should be adequately screened for bipolar disorder prior to initiating an antidepressant. Such screening should include a detailed psychiatric history, including a family history of suicide, bipolar disorder, and depression. Patients with depression or comorbid depression in the setting of other psychiatric illness being treated with antidepressants should be observed for clinical worsening and suicidality, especially during the initial few months of a course of drug therapy, or at times of dose changes. Caregivers should be advised to closely observe the patient on a daily basis and to communicate immediately with the prescriber the emergence of agitation, irritability, unusual changes in behavior, or emergence of suicidality.

Fluoxetine should be used cautiously in patients with hepatic disease or dysfunction. In patients with cirrhosis, the elimination half-lives of fluoxetine and norfluoxetine are significantly prolonged. In addition, because fluoxetine treatment has been associated with prolongation of the QTc interval and significant arrhythmias, caution is advisable when using fluoxetine in patients with conditions that predispose to increased fluoxetine exposure such as hepatic impairment. If fluoxetine is administered to a patient with hepatic impairment, a lower dose or less frequent dosing interval should be used.

QT prolongation and ventricular arrhythmias, including torsade de pointes, have been reported in patients treated with fluoxetine. Consider obtaining a baseline ECG in addition to periodic ECG monitoring if initiating fluoxetine treatment in a patient with risk factors for QT prolongation and TdP. Discontinue fluoxetine and obtain prompt cardiac evaluation if patients develop signs or symptoms consistent with ventricular arrhythmia. Use fluoxetine with caution in patients with congenital long QT syndrome, a previous history of QT prolongation, or a family history of long QT syndrome or sudden cardiac death. Use fluoxetine with caution in patients with conditions that may increase the risk of QT prolongation including bradycardia, AV block, heart failure, stress-related cardiomyopathy, myocardial infarction, stroke, or in patients receiving medications known to prolong the QT interval. Females, people 65 years and older, patients with sleep deprivation, pheochromocytoma, sickle cell disease, hypothyroidism, hyperparathyroidism, hypothermia, systemic inflammation (e.g., human immunodeficiency virus (HIV) infection, fever, and some autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus (SLE), and celiac disease) and patients undergoing apheresis procedures (e.g., plasmapheresis [plasma exchange], cytapheresis) may also be at increased risk for QT prolongation. In addition, conditions that predispose patients to increased fluoxetine exposure (e.g., overdose, hepatic impairment, CYP2D6 poor metabolizers, concomitant use of CYP2D6 inhibitors or highly protein-bound drugs) may put patients at risk. Use fluoxetine with caution in patients with conditions that may increase the risk of QT prolongation including hypomagnesemia, hypokalemia, hypocalcemia, or in patients receiving medications known to cause electrolyte imbalances; correct electrolyte imbalances prior to initiating treatment. Caution is recommended when treating patients at risk for a significant electrolyte imbalance (e.g., diuretic therapy, diarrhea).

Selective serotonin reuptake inhibitors (SSRIs), including fluoxetine, have been associated with cases of clinically significant hyponatremia, which is frequently the result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). In some cases, serum sodium levels less than 110 mmol/L have been reported; however, the adverse effect appeared reversible upon discontinuation of the causative SSRI. Elderly patients, those receiving diuretics or prone to dehydration, and those who are otherwise volume depleted (e.g., hypovolemia) appear to be at greatest risk. Hyponatremia may manifest as headache, difficulty concentrating, memory impairment, confusion, weakness, and unsteadiness which may result in falls. Severe manifestations include hallucinations, syncope, seizure, coma, respiratory arrest, and death. Symptomatic hyponatremia may require discontinuation of the SSRI, as well as implementation of the appropriate medical interventions. Should adverse reactions requiring drug discontinuation occur, the long half-life of fluoxetine and its major metabolite must be kept in mind.

Monitor patients taking an SSRI, like fluoxetine, for signs and symptoms of bleeding. Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage). Concurrent use of aspirin, NSAIDs, anticoagulant therapy, thrombolytic therapy, or other medications that enhance bleeding potential may increase this risk. Patients should be instructed to promptly report any bleeding events to the practitioner.

Caution is recommended when prescribing fluoxetine to patients with closed-angle glaucoma. The pupillary dilation that can occur with antidepressants may precipitate a closed-angle glaucoma attack in patients with anatomically narrow angles who do not have a patent iridectomy. An acute attack of closed-angle glaucoma is considered a medical emergency because the increased intraocular pressure is rapid and severe, and may quickly result in blindness if left untreated.

Fluoxetine may impair judgment, thinking, or motor skills. Patients should use caution when driving or operating machinery, until they are reasonably certain that fluoxetine does not affect them adversely. As with other psychotropic medications, patients should be advised to avoid ethanol ingestion while taking fluoxetine.

In patients with diabetes mellitus, fluoxetine may alter glycemic control. Hypoglycemia has occurred during fluoxetine therapy, and hyperglycemia has developed following discontinuation of the drug. As is true with many other types of medication when taken concurrently by patients with diabetes, insulin and/or oral hypoglycemic, dosage may need to be adjusted when therapy with fluoxetine is instituted or discontinued.

Decreased appetite and weight loss have been observed during administration of SSRIs. Therefore, caution is advisable when administering fluoxetine to patients with anorexia nervosa or other conditions where weight loss is undesirable.

Use selective serotonin reuptake inhibitors (SSRIs), including fluoxetine, with caution in patients with osteoporosis. Epidemiological studies on bone fracture risk following exposure to SSRIs have reported an association between SSRI treatment and bone fractures. It is unknown to what extent fracture risk is directly attributable to SSRI treatment. If a SSRI-treated patient presents with unexplained bone pain, point tenderness, swelling, or bruising, consider the possibility of a fragility fracture. Patients at risk for osteoporosis, such as postmenopausal females, may benefit from more frequent monitoring of bone density during long-term use of an SSRI.

Sexual dysfunction can occur in individuals taking fluoxetine. For males, these effects may present as ejaculatory failure or delay, decreased libido, and/or erectile dysfunction. Females may experience decreased libido and delayed or absent orgasm. Prescribers should discuss sexual function prior to initiating treatment with fluoxetine and throughout treatment and obtain a detailed history and timeline of any changes in sexual function to determine whether the changes are medication-related or may be attributed to the underlying psychiatric disorder. Clinicians should also discuss management strategies and treatment options with patients.

Available data from published epidemiologic studies and postmarketing reports have not established an increased risk of major birth defects or miscarriage from the use of fluoxetine during pregnancy. There are risks to the mother associated with untreated depression (e.g., relapse) and a potential risk of persistent pulmonary hypertension of the newborn (PPHN). Several publications reported an increased incidence of cardiovascular malformations in children with in utero exposure to fluoxetine. However, a causal relationship has not been established due to methodologic limitations of the studies, including possible exposure and outcome misclassification, lack of adequate controls, adjustment for confounders and confirmatory studies. Some neonates exposed to SSRIs late in the third trimester have experienced poor neonatal adaptation resulting in complications requiring prolonged hospitalization, respiratory support, and tube feeding upon delivery. Symptoms have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor, jitteriness, irritability, and constant crying. These features are consistent with direct SSRI toxicity, serotonin syndrome, or a drug discontinuation syndrome. The effect of SSRIs on labor and delivery in humans is unknown. There is a pregnancy exposure registry that monitors outcomes in pregnant patients exposed to fluoxetine; information about the registry can be obtained at https://womensmentalhealth.org/research/pregnancyregistry/antidepressants or by calling 1-866-961-2388. 

Fluoxetine and norfluoxetine are present in human milk. There are reports of agitation, irritability, poor feeding, and poor weight gain in infants exposed to fluoxetine through breast milk. There are no data on the effect of fluoxetine or its metabolites on milk production. Consider the developmental and health benefits of breastfeeding along with the clinical need for fluoxetine and any potential adverse effects on the breastfed child. Patients should advise their care team of the intention to breastfeed. Monitor the breastfed child for agitation, irritability, poor feeding, and poor weight gain.[32127] [44058] In one study of 19 nursing mothers taking fluoxetine (10 to 60 mg/day), fluoxetine was detectable in 30% of nursing infant sera (range: 1 to 84 ng/mL) and the active metabolite norfluoxetine was found in 85% (range: 1 ng/mL or less and up to 265 ng/mL). However, in lactating women taking 20 mg/day or less, infant serum concentrations were typically low. In one breast-milk sample, the concentration of fluoxetine plus norfluoxetine was 70.4 ng/mL and the concentration in the mother's plasma was 295.0 ng/mL; no adverse effects on the infant were reported. In another case, an infant nursed by a mother taking fluoxetine developed crying, sleep disturbance, vomiting, and watery stools. The infant's plasma drug levels were 340 ng/mL of fluoxetine and 208 ng/mL of norfluoxetine on the second day of feeding. Alternative medications may be considered. A pooled analysis found that maternal use of sertraline, nortriptyline, and paroxetine usually produced undetectable or low drug concentrations in infant serum and, therefore, may be the preferred antidepressants in breast-feeding mothers.[45642]

In clinical trials of fluoxetine, no overall differences in safety were observed between geriatric and younger adults, and other reported clinical experience has not identified differences in responses, but greater sensitivity of some older adults cannot be ruled out.[32127] [44058] Selective serotonin reuptake inhibitors (SSRIs) may cause hyponatremia and syndrome of inappropriate antidiuretic hormone secretion (SIADH); elderly patients appear to be at greater risk.[32127] [44058] Despite these cautions, the selective serotonin reuptake inhibitors (SSRIs) are often a preferred antidepressant group for treatment of depression or other behavioral symptoms in the elderly, including patients with dementia.  According to the Beers Criteria, SSRIs are considered potentially inappropriate medications (PIMs) in elderly patients with a history of falls or fractures and should be avoided, unless safer alternatives are not available. SSRIs can produce ataxia, impaired psychomotor function, syncope, and additional falls. If an SSRI must be used, consider reducing the use of other CNS-active medications that increase the risk of falls and fractures, and implement other strategies to reduce fall risk. Also, SSRIs can cause or exacerbate hyponatremia and SIADH, and the elderly are at increased risk of developing these conditions. Sodium levels should be closely monitored when starting or changing dosages in older adults.[63923] The federal Omnibus Budget Reconciliation Act (OBRA) regulates the use of antidepressants in residents of long-term care facilities; treatment duration should follow recommendations of pertinent literature and clinical practice guidelines for the condition treated. Monitor treated patients closely for worsening of depression and suicidal behavior or thinking, especially during initiation of therapy and during dose changes. Antidepressants may cause a variety of adverse effects; some side effects can increase the risk of falls. Before discontinuation, many antidepressants, such as the SSRIs, may need a taper to avoid a withdrawal syndrome. At least quarterly, the facility should review the continued need of the antidepressant and document the rationale for continuation. When the drug is being used to manage behavior, stabilize mood, or treat a psychiatric disorder, the facility should attempt to taper the medication as outlined in the OBRA guidelines, unless a taper is clinically contraindicated.[60742]

ADVERSE REACTIONS

visual impairment / Early / 2.0-2.0
tardive dyskinesia / Delayed / 0.1-1.0
suicidal ideation / Delayed / 0.1-1.0
arrhythmia exacerbation / Early / 0.1-1.0
heart failure / Delayed / 0.1-1.0
myocardial infarction / Delayed / 0.1-1.0
proteinuria / Delayed / 0.1-1.0
seizures / Delayed / 0-0.2
peptic ulcer / Delayed / 0-0.1
hematemesis / Delayed / 0-0.1
GI bleeding / Delayed / 0-0.1
pancreatitis / Delayed / 0-0.1
cholecystitis / Delayed / 0-0.1
esophageal ulceration / Delayed / 0-0.1
GI obstruction / Delayed / 0-0.1
muscle paralysis / Delayed / 0-0.1
pulmonary hypertension / Delayed / 0-0.1
thrombosis / Delayed / 0-0.1
ventricular fibrillation / Early / 0-0.1
coronary vasospasm / Early / 0-0.1
stroke / Early / 0-0.1
atrial fibrillation / Early / 0-0.1
cardiac arrest / Early / 0-0.1
bradycardia / Rapid / 0-0.1
pneumothorax / Early / 0-0.1
apnea / Delayed / 0-0.1
pulmonary edema / Early / 0-0.1
laryngeal edema / Rapid / 0-0.1
ocular hypertension / Delayed / 0-0.1
hearing loss / Delayed / 0-0.1
oliguria / Early / 0-0.1
diabetic ketoacidosis / Delayed / 0-0.1
hyperkalemia / Delayed / 0-0.1
torticollis / Delayed / Incidence not known
thrombotic thrombocytopenic purpura (TTP) / Delayed / Incidence not known
aplastic anemia / Delayed / Incidence not known
hemolytic anemia / Delayed / Incidence not known
SIADH / Delayed / Incidence not known
torsade de pointes / Rapid / Incidence not known
ventricular tachycardia / Early / Incidence not known
erythema nodosum / Delayed / Incidence not known
pulmonary fibrosis / Delayed / Incidence not known
lupus-like symptoms / Delayed / Incidence not known
bronchospasm / Rapid / Incidence not known
erythema multiforme / Delayed / Incidence not known
exfoliative dermatitis / Delayed / Incidence not known
Stevens-Johnson syndrome / Delayed / Incidence not known
anaphylactoid reactions / Rapid / Incidence not known
angioedema / Rapid / Incidence not known
serum sickness / Delayed / Incidence not known
vasculitis / Delayed / Incidence not known
Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) / Delayed / Incidence not known
laryngospasm / Rapid / Incidence not known
toxic epidermal necrolysis / Delayed / Incidence not known
eosinophilic pneumonia / Delayed / Incidence not known
pulmonary embolism / Delayed / Incidence not known
optic neuritis / Delayed / Incidence not known
hepatic failure / Delayed / Incidence not known
hepatic necrosis / Delayed / Incidence not known
renal failure (unspecified) / Delayed / Incidence not known
bone fractures / Delayed / Incidence not known
serotonin syndrome / Delayed / Incidence not known
persistent pulmonary hypertension of the newborn / Delayed / Incidence not known
neonatal abstinence syndrome / Early / Incidence not known

impotence (erectile dysfunction) / Delayed / 1.0-7.0
ejaculation dysfunction / Delayed / 2.0-7.0
constipation / Delayed / 5.0-5.0
oral ulceration / Delayed / 0.1-1.0
melena / Delayed / 0.1-1.0
esophagitis / Delayed / 0.1-1.0
cholelithiasis / Delayed / 0.1-1.0
dysphagia / Delayed / 0.1-1.0
glossitis / Early / 0.1-1.0
gastritis / Delayed / 0.1-1.0
colitis / Delayed / 0.1-1.0
stomatitis / Delayed / 0.1-1.0
neuropathic pain / Delayed / 0.1-1.0
myoclonia / Delayed / 0.1-1.0
teeth grinding (bruxism) / Delayed / 0.1-1.0
migraine / Early / 0.1-1.0
akathisia / Delayed / 0.1-1.0
ataxia / Delayed / 0.1-1.0
hypertonia / Delayed / 0.1-1.0
hostility / Early / 0.1-1.0
psychosis / Early / 0.1-1.0
euphoria / Early / 0.1-1.0
depression / Delayed / 0.1-1.0
anemia / Delayed / 0.1-1.0
hypotension / Rapid / 0.1-1.0
angina / Early / 0.1-1.0
orthostatic hypotension / Delayed / 0.1-1.0
peripheral edema / Delayed / 0.1-1.0
edema / Delayed / 0.1-1.0
vaginal bleeding / Delayed / 0.1-1.0
atopic dermatitis / Delayed / 0.1-1.0
skin ulcer / Delayed / 0.1-1.0
photophobia / Early / 0.1-1.0
conjunctivitis / Delayed / 0.1-1.0
elevated hepatic enzymes / Delayed / 0.1-1.0
urinary incontinence / Early / 0.1-1.0
dysuria / Early / 0.1-1.0
hematuria / Delayed / 0.1-1.0
urinary retention / Early / 0.1-1.0
cystitis / Delayed / 0.1-1.0
hypothyroidism / Delayed / 0.1-1.0
hypercholesterolemia / Delayed / 0.1-1.0
dehydration / Delayed / 0.1-1.0
hypokalemia / Delayed / 0.1-1.0
hyperlipidemia / Delayed / 0.1-1.0
gout / Delayed / 0.1-1.0
bone pain / Delayed / 0.1-1.0
synovitis / Delayed / 0.1-1.0
mania / Early / 0.7-0.7
abdominal pain / Early / 0-0.1
fecal incontinence / Early / 0-0.1
neuritis / Delayed / 0-0.1
hallucinations / Early / 0-0.1
EEG changes / Delayed / 0-0.1
dysarthria / Delayed / 0-0.1
hyperesthesia / Delayed / 0-0.1
dystonic reaction / Delayed / 0-0.1
lymphocytosis / Delayed / 0-0.1
thrombocytopenia / Delayed / 0-0.1
leukopenia / Delayed / 0-0.1
phlebitis / Rapid / 0-0.1
priapism / Early / 0-0.1
psoriasis / Delayed / 0-0.1
furunculosis / Delayed / 0-0.1
hypoxia / Early / 0-0.1
hypoventilation / Rapid / 0-0.1
hemoptysis / Delayed / 0-0.1
blepharitis / Early / 0-0.1
iritis / Delayed / 0-0.1
exophthalmos / Delayed / 0-0.1
hyperacusis / Delayed / 0-0.1
hepatitis / Delayed / 0-0.1
flank pain / Delayed / 0-0.1
glycosuria / Early / 0-0.1
hyperglycemia / Delayed / 0-0.1
diabetes mellitus / Delayed / 0-0.1
hypocalcemia / Delayed / 0-0.1
hyperuricemia / Delayed / 0-0.1
myopathy / Delayed / 0-0.1
myasthenia / Delayed / 0-0.1
osteoporosis / Delayed / 0-0.1
confusion / Early / 1.0
amnesia / Delayed / 1.0
QT prolongation / Rapid / 1.0
hypertension / Early / 1.0
palpitations / Early / 1.0
chest pain (unspecified) / Early / 1.0
dyskinesia / Delayed / Incidence not known
memory impairment / Delayed / Incidence not known
hematoma / Early / Incidence not known
bleeding / Early / Incidence not known
platelet dysfunction / Delayed / Incidence not known
hyponatremia / Delayed / Incidence not known
galactorrhea / Delayed / Incidence not known
hyperprolactinemia / Delayed / Incidence not known
dyspnea / Early / Incidence not known
cataracts / Delayed / Incidence not known
jaundice / Delayed / Incidence not known
hypoglycemia / Early / Incidence not known
osteopenia / Delayed / Incidence not known
withdrawal / Early / Incidence not known
growth inhibition / Delayed / Incidence not known

insomnia / Early / 10.0-33.0
nausea / Early / 12.0-29.0
headache / Early / 21.0-21.0
asthenia / Delayed / 7.0-21.0
diarrhea / Early / 8.0-18.0
anorexia / Delayed / 4.0-17.0
drowsiness / Early / 5.0-17.0
anxiety / Delayed / 6.0-15.0
tremor / Early / 3.0-13.0
xerostomia / Early / 4.0-12.0
yawning / Early / 1.0-11.0
libido decrease / Delayed / 1.0-11.0
dyspepsia / Early / 6.0-10.0
pharyngitis / Delayed / 3.0-10.0
dizziness / Early / 9.0-9.0
hyperhidrosis / Delayed / 2.0-8.0
urticaria / Rapid / 7.0-7.0
rash / Early / 2.0-7.0
sinusitis / Delayed / 1.0-6.0
abnormal dreams / Early / 1.0-5.0
flushing / Rapid / 1.0-5.0
flatulence / Early / 3.0-3.0
vomiting / Early / 3.0-3.0
pruritus / Rapid / 3.0-3.0
weight loss / Delayed / 2.0-2.0
epistaxis / Delayed / 1.0-2.0
fever / Early / 2.0-2.0
hypersalivation / Early / 0.1-1.0
polydipsia / Early / 0.1-1.0
eructation / Early / 0.1-1.0
paranoia / Early / 0.1-1.0
vertigo / Early / 0.1-1.0
hypoesthesia / Delayed / 0.1-1.0
ecchymosis / Delayed / 0.1-1.0
syncope / Early / 0.1-1.0
breast enlargement / Delayed / 0.1-1.0
orgasm dysfunction / Delayed / 0.1-1.0
mastalgia / Delayed / 0.1-1.0
menorrhagia / Delayed / 0.1-1.0
libido increase / Delayed / 0.1-1.0
breast discharge / Delayed / 0.1-1.0
amenorrhea / Delayed / 0.1-1.0
leukorrhea / Delayed / 0.1-1.0
photosensitivity / Delayed / 0.1-1.0
alopecia / Delayed / 0.1-1.0
maculopapular rash / Early / 0.1-1.0
skin discoloration / Delayed / 0.1-1.0
acne vulgaris / Delayed / 0.1-1.0
malaise / Early / 0.1-1.0
hyperventilation / Early / 0.1-1.0
hiccups / Early / 0.1-1.0
mydriasis / Early / 0.1-1.0
xerophthalmia / Early / 0.1-1.0
nocturia / Early / 0.1-1.0
polyuria / Early / 0.1-1.0
urinary urgency / Early / 0.1-1.0
arthralgia / Delayed / 0.1-1.0
muscle cramps / Delayed / 0.1-1.0
pelvic pain / Delayed / 0.1-1.0
paresthesias / Delayed / 0-0.1
hyporeflexia / Delayed / 0-0.1
petechiae / Delayed / 0-0.1
purpura / Delayed / 0-0.1
pallor / Early / 0-0.1
hirsutism / Delayed / 0-0.1
seborrhea / Delayed / 0-0.1
parosmia / Delayed / 0-0.1
diplopia / Early / 0-0.1
appetite stimulation / Delayed / 1.0
weight gain / Delayed / 1.0
dysgeusia / Early / 1.0
emotional lability / Early / 1.0
hyperkinesis / Delayed / 2.0
agitation / Early / 1.0
hypothermia / Delayed / 1.0
chills / Rapid / 1.0
otalgia / Early / 1.0
tinnitus / Delayed / 1.0
increased urinary frequency / Early / 1.0
gynecomastia / Delayed / Incidence not known
influenza / Delayed / Incidence not known

DRUG INTERACTIONS

Abciximab: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving abciximab. Monitor closely for signs and symptoms of bleeding.
Abemaciclib: (Moderate) Monitor for an increase in abemaciclib-related adverse reactions if coadministration with fluoxetine is necessary; consider reducing the dose of abemaciclib in 50-mg decrements if toxicities occur. Discontinue abemaciclib for patients unable to tolerate 50 mg twice daily. Abemaciclib is a CYP3A4 substrate. Fluoxetine is a weak CYP3A4 inhibitor, but its metabolite, norfluoxetine, is a moderate CYP3A4 inhibitor. Coadministration with other moderate CYP3A4 inhibitors is predicted to increase the relative potency adjusted unbound AUC of abemaciclib plus its active metabolites (M2, M18, and M20) by approximately 1.6- to 2.4-fold.
Abrocitinib: (Major) Do not exceed an initial abrocitinib dose of 50 mg PO once daily or a maximum dose of 100 mg PO once daily if coadministered with fluoxetine. Concurrent use may increase the combined exposure of abrocitinib and its 2 active metabolites; monitor closely for adverse reactions. Abrocitinib is a CYP2C19 substrate and fluoxetine is a strong CYP2C19 inhibitor.
Acarbose: (Moderate) In patients with diabetes mellitus, fluoxetine may alter glycemic control. Hypoglycemia has occurred during fluoxetine therapy. Hyperglycemia has developed in patients with diabetes mellitus following discontinuation of the drug. The dosage of insulin and/or other antidiabetic agents may need to be adjusted when therapy with fluoxetine is instituted or discontinued.
Acetaminophen; Aspirin, ASA; Caffeine: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Acetaminophen; Aspirin: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Acetaminophen; Aspirin; Diphenhydramine: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of dihydrocodeine and fluoxetine because of the potential risk of serotonin syndrome, reduced dihydrocodeine efficacy, and potential for opioid withdrawal symptoms. Discontinue dihydrocodeine if serotonin syndrome is suspected. Concomitant use may increase dihydrocodeine plasma concentrations, but decrease the plasma concentration of the active metabolite, dihydromorphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of dihydrocodeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease dihydrocodeine plasma concentrations and increase dihydromorphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Dihydrocodeine is primarily metabolized by CYP2D6 to dihydromorphine, and by CYP3A4. Fluoxetine is a strong inhibitor of CYP2D6.
Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6.
Acetaminophen; Dextromethorphan: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Acetaminophen; Hydrocodone: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Acetaminophen; Oxycodone: (Moderate) If concomitant use of oxycodone and fluoxetine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Acetaminophen; Pentazocine: (Major) Because of the potential risk and severity of serotonin syndrome reactions, caution should be observed when administering selective serotonin reuptake inhibitors (SSRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If serotonin syndrome occurs, discontinue the offending agent(s) and institute appropriate therapy.
Adagrasib: (Major) Avoid concomitant use of adagrasib and fluoxetine due to the potential for increased fluoxetine exposure and additive risk for QT/QTc prolongation and torsade de pointes (TdP). If use is necessary, monitor for fluoxetine-related adverse effects and consider taking additional steps to minimize the risk for QT prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring. Fluoxetine is a CYP2D6 substrate, adagrasib is a moderate CYP2D6 inhibitor, and both medications have been associated with QT interval prolongation.
Albiglutide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Alfentanil: (Moderate) Alfentanil is metabolized by the cytochrome P450 3A4 isoenzyme present in the liver. Inhibitors of CYP3A4, such as fluoxetine, may decrease systemic clearance of alfentanil leading to increased or prolonged effects. Close monitoring for oversedation and respiratory depression is warranted if a CYP3A4 inhibitor is used with alfentanil.
Alfuzosin: (Moderate) Concomitant use of fluoxetine and alfuzosin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Almotriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering almotriptan with fluoxetine. Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and selective serotonin reuptake inhibitors (SSRIs). Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly after a dose increase of the SSRI or the addition of other serotonergic medications to an existing SSRI regimen. Discontinue fluoxetine and almotriptan and initiate symptomatic treatment if serotonin syndrome occurs.
Alogliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Alogliptin; Metformin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Alogliptin; Pioglitazone: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Alpha-glucosidase Inhibitors: (Moderate) In patients with diabetes mellitus, fluoxetine may alter glycemic control. Hypoglycemia has occurred during fluoxetine therapy. Hyperglycemia has developed in patients with diabetes mellitus following discontinuation of the drug. The dosage of insulin and/or other antidiabetic agents may need to be adjusted when therapy with fluoxetine is instituted or discontinued.
Alprazolam: (Major) Avoid coadministration of alprazolam and fluoxetine due to the potential for elevated alprazolam concentrations, which may cause prolonged sedation and respiratory depression. Coadministration of alprazolam and fluoxetine has resulted in increased alprazolam plasma concentrations and in further psychomotor performance decrement due to increased alprazolam levels. If coadministration is necessary, consider reducing the dose of alprazolam as clinically appropriate and monitor for an increase in alprazolam-related adverse reactions. Lorazepam, oxazepam, or temazepam may be safer alternatives if a benzodiazepine must be administered in combination with fluoxetine, as these benzodiazepines are not oxidatively metabolized. Alprazolam is a CYP3A4 substrate and fluoxetine is a weak CYP3A4 inhibitor. Norfluoxetine, the active metabolite of fluoxetine, is a moderate CYP3A4 inhibitor. Coadministration with fluoxetine increased alprazolam maximum concentration by 46%, decreased clearance by 21%, increased half-life by 17%, and decreased measured psychomotor performance.
Alteplase: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving thrombolytic agents. Patients should be closely monitored for signs and symptoms of bleeding when a thrombolytic agent is administered with an SSRI.
Amiloride: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Amiodarone: (Major) Concomitant use of amiodarone and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary. Due to the extremely long half-life of amiodarone, a drug interaction is possible for days to weeks after drug discontinuation.
Amisulpride: (Major) Monitor ECGs for QT prolongation when amisulpride is administered with fluoxetine. Amisulpride causes dose- and concentration- dependent QT prolongation. QT prolongation and TdP have been reported in patients treated with fluoxetine.
Amitriptyline: (Moderate) Monitor for signs and symptoms of serotonin syndrome, particularly during treatment initiation and dosage increase, during concomitant amitriptyline and fluoxetine use. If serotonin syndrome occurs, discontinue therapy. Concomitant use increases the risk for serotonin syndrome.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Amoxapine: (Moderate) Fluoxetine, a potent CYP2D6 inhibitor, may increase the plasma concentrations of the tetracyclic antidepressant amoxapine, which is partially metabolized by CYP2D6. In several cases, symptoms of toxicity, including seizures, have been reported when tricyclic antidepressants were coadministered with an SSRI, including fluoxetine. At least one case report exists of a death thought to be due to impaired clearance of the tricyclic antidepressant amitriptyline by fluoxetine. Also, this combination may represent duplicative therapy. Patients receiving amoxapine should be monitored closely for toxicity if fluoxetine is added. Monitoring should be continued for several weeks following the discontinuation of fluoxetine due to the long half-life of norfluoxetine, the active metabolite of fluoxetine which has a half-life of 7 to 9 days and is a CYP2D6 inhibitor.
Amoxicillin; Clarithromycin; Omeprazole: (Major) Concomitant use of clarithromycin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Amphetamines: (Moderate) Monitor for signs and symptoms of serotonin syndrome, particularly during treatment initiation and dosage increase, during concomitant amphetamine and fluoxetine use. If serotonin syndrome occurs, discontinue therapy. Concomitant use increases the risk for serotonin syndrome.
Anagrelide: (Major) Do not use anagrelide with other drugs that prolong the QT interval, such as fluoxetine. Torsade de pointes (TdP) and ventricular tachycardia have been reported with anagrelide; dose-related increases in mean QTc and heart rate were observed in healthy subjects. QT prolongation and TdP have been reported in patients treated with fluoxetine. In addition, platelet aggregation may be impaired by SSRIs due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving platelet inhibitors.
Antithrombin III: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like antithrombin III. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Apixaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like apixaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Apomorphine: (Moderate) Concomitant use of fluoxetine and apomorphine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Aprepitant, Fosaprepitant: (Moderate) Use caution if fluoxetine and aprepitant are used concurrently and monitor for an increase in fluoxetine-related adverse effects for several days after administration of a multi-day aprepitant regimen. After administration, fosaprepitant is rapidly converted to aprepitant and shares the same drug interactions. Fluoxetine is a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer; substitution of fosaprepitant 115 mg IV on day 1 of the 3-day regimen may lessen the inhibitory effects of CYP3A4. The AUC of a single dose of another CYP3A4 substrate, midazolam, increased by 2.3-fold and 3.3-fold on days 1 and 5, respectively, when coadministered with a 5-day oral aprepitant regimen. After a 3-day oral aprepitant regimen, the AUC of midazolam increased by 25% on day 4, and decreased by 19% and 4% on days 8 and 15, respectively, when given on days 1, 4, 8, and 15. As a single 40-mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.2-fold; the midazolam AUC increased by 1.5-fold after a single 125-mg dose of oral aprepitant. After single doses of IV fosaprepitant, the midazolam AUC increased by 1.8-fold (150 mg) and 1.6-fold (100 mg); less than a 2-fold increase in the midazolam AUC is not considered clinically important. Fluoxetine is also a weak CYP3A4 inhibitor and aprepitant is a CYP3A4 substrate. Coadministration of daily oral aprepitant (230 mg, or 1.8 times the recommended single dose) with a moderate CYP3A4 inhibitor, diltiazem, increased the aprepitant AUC 2-fold with a concomitant 1.7-fold increase in the diltiazem AUC; clinically meaningful changes in ECG, heart rate, or blood pressure beyond those induced by diltiazem alone did not occur. Information is not available regarding the use of aprepitant with weak CYP3A4 inhibitors.
Aripiprazole: (Major) Reduce the oral aripiprazole dosage by one-half of the usual dose in patients receiving strong CYP2D6 inhibitors such as fluoxetine. Reduce the oral aripiprazole dosage to one-quarter (25%) of the usual dose with subsequent adjustments based upon clinical response in patients also receiving a CYP3A4 inhibitor, as aripiprazole is also metabolized by CYP3A4. Addtionally, aripiprazole and fluoxetine are both associated with prolongation of the QT interval; caution and close monitoring are recommended. Avoid concurrent use of Aristada Initio and fluoxetine because the dose of Aristada Initio cannot be modified. For other long-active aripiprazole injectables (e.g., Ability Maintena, Aristada), dose adjustments are recommended with strong CYP2D6 inhibitors and combined strong CYP2D6/CYP3A4 inhibitors; the recommendations are dependent on the aripiprazole IM depot dosage, the product given, and the duration of the concomitant inhibitors as specified in the product labels.
Armodafinil: (Moderate) Armodafinil is partially metabolized by CYP3A4/5 isoenzymes. Interactions with potent inhibitors of CYP3A4 such as fluoxetine are possible. However, because armodafinil is itself an inducer of the CYP3A4 isoenzyme, drug interactions due to CYP3A4 inhibition by other medications may be complex and difficult to predict. Observation of the patient for increased effects from armodafinil may be needed.
Arsenic Trioxide: (Major) Avoid coadministration of fluoxetine and arsenic trioxide. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. If possible, drugs that are known to prolong the QT interval should be discontinued prior to initiating arsenic trioxide therapy. If concomitant drug use is unavoidable, frequently monitor electrocardiograms. QT prolongation should be expected with the administration of arsenic trioxide.
Artemether; Lumefantrine: (Major) Avoid coadministration of fluoxetine and artemether; lumefantrine due to the potential for additive QT prolongation. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. Artemether; lumefantrine is also associated with QT interval prolongation. (Moderate) Lumefantrine is an inhibitor and fluoxetine is a substrate/inhibitor of the CYP2D6 isoenzyme; therefore, coadministration may lead to increased fluoxetine concentrations. Additionally, lumefantrine is a substrate and fluoxetine is an inhibitor of the CYP3A4 isoenzyme; therefore, concomitant use may lead to increased lumefantrine concentrations. Concomitant use warrants caution due to the potential for increased side effects.
Asenapine: (Major) Concomitant use of asenapine and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Aspirin, ASA: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Butalbital; Caffeine; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6. (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Caffeine: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Caffeine; Orphenadrine: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Carisoprodol: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation. (Minor) Carisoprodol is extensively metabolized and is a significant substrate of CYP2C19 isoenzymes. Theoretically, CY2C19 inhibitors, such as fluoxetine, could increase carisoprodol plasma levels, with potential for enhanced CNS depressant effects.
Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6. (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation. (Minor) Carisoprodol is extensively metabolized and is a significant substrate of CYP2C19 isoenzymes. Theoretically, CY2C19 inhibitors, such as fluoxetine, could increase carisoprodol plasma levels, with potential for enhanced CNS depressant effects.
Aspirin, ASA; Citric Acid; Sodium Bicarbonate: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Dipyridamole: (Moderate) Platelet aggregation may be impaired by SSRIs due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving platelet inhibitors. Monitor for signs and symptoms of bleeding. (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Omeprazole: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Oxycodone: (Moderate) If concomitant use of oxycodone and fluoxetine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Aspirin, ASA; Pravastatin: (Moderate) The combined use of selective serotonin reuptake inhibitors and aspirin, ASA may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation.
Atazanavir; Cobicistat: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Atenolol; Chlorthalidone: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Atomoxetine: (Major) Monitor for evidence of QT prolongation and increased atomoxetine-related adverse effects during coadministration with fluoxetine. Dosage reduction of atomoxetine is recommended in patients receiving fluoxetine due to the potential for increased atomoxetine exposure and related adverse effects. In children and adolescents up to 70 kg receiving fluoxetine, atomoxetine should be initiated at 0.5 mg/kg/day and only increased to the usual target dose of 1.2 mg/kg/day if symptoms fail to improve after 4 weeks and the initial dose is well-tolerated. In children and adolescents over 70 kg and adults receiving fluoxetine, atomoxetine should be initiated at 40 mg/day and only increased to the usual target dose of 80 mg/day if symptoms fail to improve after 4 weeks and the initial dose is well-tolerated. Fluoxetine is a strong CYP2D6 inhibitor; atomoxetine is a CYP2D6 substrate. Coadministration of a strong CYP2D6 inhibitor and atomoxetine in extensive metabolizers of CYP2D6, increased atomoxetine steady-state plasma concentrations by approximately 6 to 8-fold. This increase is similar to exposures observed in poor metabolizers. Concurrent use of a strong CYP2D6 inhibitor with atomoxetine in poor metabolizers is not expected to increase atomoxetine exposure.
Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Contraindicated) According to the manufacturer of fluoxetine, treatment initiation with fluoxetine is contraindicated in patients currently receiving intravenous (IV) methylene blue due to an increased risk of serotonin syndrome. If urgent psychiatric treatment is required, interventions other than fluoxetine (e.g., alternative medication, hospitalization) should be considered. Conversely, in patients receiving fluoxetine and requiring urgent treatment with IV methylene blue, fluoxetine should be discontinued immediately and methylene blue therapy initiated only if acceptable alternatives are not available and the potential benefits outweigh the risks. The patient should be monitored for serotonin syndrome for 5 weeks or until 24 hours after the last dose of methylene blue, whichever comes first. Fluoxetine may be re-initiated 24 hours after the last dose of methylene blue. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with a serotonergic agent may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent, in patients receiving SSRIs, serotonin/norepinephrine reuptake inhibitors, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with IV methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case describes a patient receiving citalopram who experienced agitation, restlessness, pupil dilation with sluggish response to light, myoclonic movements of the lower limbs, and brisk reflexes following an infusion of methylene blue, while another patient receiving paroxetine developed tachycardia, agitation, dystonia and abnormal eye movements. During a retrospective study of 193 surgical patients who had received a methylene blue injection, it was found that all 12 of the patients who experienced postoperative neurological sequelae had been taking a serotonin reuptake inhibitor preoperatively. One of the 12 patients experienced cardiopulmonary arrest and died. Of the remaining 181 patients who did not experience neurological sequelae, 8.8% were taking a serotonin reuptake inhibitor. Published interaction reports between IV methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. (Moderate) The combined use of selective serotonin reuptake inhibitors (SSRIs) and aspirin, ASA or other salicylates which affect hemostasis may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin.
Atropine; Difenoxin: (Moderate) Concurrent administration of diphenoxylate/difenoxin with fluoxetine can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration.
Azilsartan; Chlorthalidone: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Azithromycin: (Major) Concomitant use of azithromycin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Bedaquiline: (Major) Bedaquiline has been reported to prolong the QT interval. Prior to initiating bedaquiline, obtain serum electrolyte concentrations and a baseline ECG. An ECG should also be performed at least 2, 12, and 24 weeks after starting bedaquiline therapy. Coadministration with other QT prolonging drugs may result in additive or synergistic prolongation of the QT interval. Drugs with a possible risk for QT prolongation and torsade de pointes (TdP) that should be used cautiously and with close monitoring with bedaquiline include fluoxetine.
Belladonna; Opium: (Major) Fluoxetine may inhibit the metabolism of opium. Clinicians should be alert for an exaggerated opiate response if opium is given with fluoxetine.
Belzutifan: (Moderate) Monitor for anemia and hypoxia if concomitant use of fluoxetine with belzutifan is necessary due to increased plasma exposure of belzutifan which may increase the incidence and severity of adverse reactions. Reduce the dose of belzutifan as recommended if anemia or hypoxia occur. Belzutifan is a CYP2C19 substrate and fluoxetine is a CYP2C19 inhibitor.
Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Bendroflumethiazide; Nadolol: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Benzhydrocodone; Acetaminophen: (Moderate) Concurrent use of benzhydrocodone with fluoxetine may increase the risk of increased opioid-related adverse reactions, such as fatal respiratory depression. Consider a dose reduction of benzhydrocodone until stable drug effects are achieved. Monitor patients for respiratory depression and sedation at frequent intervals. Discontinuation of fluoxetine in a patient taking benzhydrocodone may decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to opioid agonists. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Benzhydrocodone is a prodrug for hydrocodone. Hydrocodone is a substrate for CYP3A4 and CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6 and a weak inhibitor of CYP3A4. Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of benzhydrocodone and fluoxetine because of the potential risk of serotonin syndrome. Discontinue benzhydrocodone if serotonin syndrome is suspected. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Contraindicated) According to the manufacturer of fluoxetine, treatment initiation with fluoxetine is contraindicated in patients currently receiving intravenous (IV) methylene blue due to an increased risk of serotonin syndrome. If urgent psychiatric treatment is required, interventions other than fluoxetine (e.g., alternative medication, hospitalization) should be considered. Conversely, in patients receiving fluoxetine and requiring urgent treatment with IV methylene blue, fluoxetine should be discontinued immediately and methylene blue therapy initiated only if acceptable alternatives are not available and the potential benefits outweigh the risks. The patient should be monitored for serotonin syndrome for 5 weeks or until 24 hours after the last dose of methylene blue, whichever comes first. Fluoxetine may be re-initiated 24 hours after the last dose of methylene blue. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with a serotonergic agent may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent, in patients receiving SSRIs, serotonin/norepinephrine reuptake inhibitors, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with IV methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case describes a patient receiving citalopram who experienced agitation, restlessness, pupil dilation with sluggish response to light, myoclonic movements of the lower limbs, and brisk reflexes following an infusion of methylene blue, while another patient receiving paroxetine developed tachycardia, agitation, dystonia and abnormal eye movements. During a retrospective study of 193 surgical patients who had received a methylene blue injection, it was found that all 12 of the patients who experienced postoperative neurological sequelae had been taking a serotonin reuptake inhibitor preoperatively. One of the 12 patients experienced cardiopulmonary arrest and died. Of the remaining 181 patients who did not experience neurological sequelae, 8.8% were taking a serotonin reuptake inhibitor. Published interaction reports between IV methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. (Moderate) The combined use of selective serotonin reuptake inhibitors (SSRIs) and aspirin, ASA or other salicylates which affect hemostasis may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin.
Berotralstat: (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with berotralstat. Concurrent use may result in increased fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and berotralstat is a moderate CYP2D6 inhibitor.
Betrixaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like betrixaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Bismuth Subcitrate Potassium; Metronidazole; Tetracycline: (Moderate) Concomitant use of metronidazole and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Bismuth Subsalicylate: (Moderate) The combined use of selective serotonin reuptake inhibitors (SSRIs) and aspirin, ASA or other salicylates which affect hemostasis may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin.
Bismuth Subsalicylate; Metronidazole; Tetracycline: (Moderate) Concomitant use of metronidazole and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. (Moderate) The combined use of selective serotonin reuptake inhibitors (SSRIs) and aspirin, ASA or other salicylates which affect hemostasis may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin.
Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Bortezomib: (Minor) Agents that inhibit cytochrome P450 3A4 may increase the exposure to bortezomib and increase the risk for toxicity; however, bortezomib is also metabolized by other CYP isoenzymes. Therefore, the clinical significance of concurrent administration of bortezomib with fluoxetine is not known.
Bosentan: (Moderate) Bosentan is metabolized by CYP2C9 and CYP3A4. Fluoxetine may inhibit both of these isoenzymes and thereby increase the plasma concentrations of bosentan. It is prudent to monitor for potential adverse effects of bosentan during coadministration with fluoxetine; excessive dosage may result in hypotension or elevated hepatic enzymes.
Brexpiprazole: (Major) Because brexpiprazole is primarily metabolized by CYP3A4 and CYP2D6, the manufacturer recommends that the brexpiprazole dose be reduced to one-half of the usual dose in patients receiving a strong CYP2D6 inhibitor and one-quarter (25%) of the usual dose in patients receiving a moderate to strong inhibitor of CYP3A4 in combination with a moderate to strong inhibitor of CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6. If these agents are used in combination, the patient should be carefully monitored for brexpiprazole-related adverse reactions. It should be noted that no dosage adjustment is needed in patients taking a strong CYP2D6 inhibitor who are receiving brexpiprazole as adjunct treatment for major depressive disorder because CYP2D6 considerations are already factored into general dosing recommendations.
Brimonidine; Timolol: (Moderate) Monitor for signs of bradycardia or heart block if coadministration of timolol with fluoxetine is necessary. Concomitant use may enhance the beta-blocking properties of timolol resulting in further slowing of the heart rate or cardiac conduction. Timolol is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor.
Brompheniramine; Dextromethorphan; Guaifenesin: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Bumetanide: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Bupivacaine Liposomal: (Minor) Bupivacaine is metabolized by CYP3A4 isoenzymes. Known inhibitors of CYP3A4, such as fluoxetine, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity.
Bupivacaine: (Minor) Bupivacaine is metabolized by CYP3A4 isoenzymes. Known inhibitors of CYP3A4, such as fluoxetine, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity.
Bupivacaine; Epinephrine: (Minor) Bupivacaine is metabolized by CYP3A4 isoenzymes. Known inhibitors of CYP3A4, such as fluoxetine, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity.
Bupivacaine; Lidocaine: (Moderate) Concomitant use of systemic lidocaine and fluoxetine may increase lidocaine plasma concentrations by decreasing lidocaine clearance and therefore prolonging the elimination half-life. Monitor for lidocaine toxicity if used together. Lidocaine is a CYP3A4 and CYP1A2 substrate; fluoxetine inhibits CYP3A4. (Minor) Bupivacaine is metabolized by CYP3A4 isoenzymes. Known inhibitors of CYP3A4, such as fluoxetine, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity.
Bupivacaine; Meloxicam: (Minor) Bupivacaine is metabolized by CYP3A4 isoenzymes. Known inhibitors of CYP3A4, such as fluoxetine, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity.
Buprenorphine: (Major) Due to the potential for QT prolongation, cautious use and close monitoring are advisable if concurrent use of fluoxetine and buprenorphine is necessary. Fluoxetine may cause QT interval prolongation and a risk for torsade de pointes (TdP); buprenorphine caused QT prolongation in some patients during clinical trials. In addition, concurrent use of opioids with other drugs that modulate serotonergic function, such as SSRIs, has resulted in serotonin syndrome in some cases. Patients should be carefully observed, particularly during treatment initiation and during dose adjustments. Discontinue the serotonergic medications if serotonin syndrome is suspected.
Buprenorphine; Naloxone: (Major) Due to the potential for QT prolongation, cautious use and close monitoring are advisable if concurrent use of fluoxetine and buprenorphine is necessary. Fluoxetine may cause QT interval prolongation and a risk for torsade de pointes (TdP); buprenorphine caused QT prolongation in some patients during clinical trials. In addition, concurrent use of opioids with other drugs that modulate serotonergic function, such as SSRIs, has resulted in serotonin syndrome in some cases. Patients should be carefully observed, particularly during treatment initiation and during dose adjustments. Discontinue the serotonergic medications if serotonin syndrome is suspected.
Bupropion: (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with bupropion. Concomitant use may increase fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and bupropion is a strong CYP2D6 inhibitor.
Bupropion; Naltrexone: (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with bupropion. Concomitant use may increase fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and bupropion is a strong CYP2D6 inhibitor.
Buspirone: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering buspirone and fluoxetine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly during treatment initiation and dose increases. If serotonin syndrome occurs, serotonergic drugs should be discontinued and appropriate medical treatment should be initiated.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6.
Cabotegravir; Rilpivirine: (Moderate) Concomitant use of fluoxetine and rilpivirine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. The degree of QT prolongation associated with rilpivirine is not clinically significant when administered within the recommended dosage range; QT prolongation has been described at 3 times the maximum recommended dose.
Canagliflozin: (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Canagliflozin; Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Cangrelor: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymosis, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors (e.g., cangrelor). Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SSRI concurrently with an antiplatelet medication and to promptly report any bleeding events to the practitioner.
Capsaicin; Metaxalone: (Moderate) Concomitant use of selective serotonin reuptake inhibitors (SSRIs) and metaxalone may increase the risk for serotonin syndrome. Monitor patients for serotonin syndrome if concomitant use is necessary.
Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Carisoprodol: (Minor) Carisoprodol is extensively metabolized and is a significant substrate of CYP2C19 isoenzymes. Theoretically, CY2C19 inhibitors, such as fluoxetine, could increase carisoprodol plasma levels, with potential for enhanced CNS depressant effects.
Carvedilol: (Minor) Inhibitors of the hepatic CYP450 isozyme CYP 2D6, such as fluoxetine, may inhibit the hepatic oxidative metabolism of carvedilol.
Celecoxib; Tramadol: (Moderate) Monitor for reduced efficacy of tramadol, signs of opioid withdrawal, seizures, or serotonin syndrome if coadministration with fluoxetine is necessary. If fluoxetine is discontinued, consider a dose reduction of tramadol and frequently monitor for signs of respiratory depression and sedation. Tramadol is a CYP2D6 substrate and fluoxetine is a CYP2D6 inhibitor. Concomitant use of tramadol with CYP2D6 inhibitors can increase the plasma concentration of tramadol and decrease the plasma concentration of the active metabolite M1. Since M1 is a more potent mu-opioid agonist, decreased M1 exposure could result in decreased therapeutic effects, and may result in signs and symptoms of opioid withdrawal in patients who have developed physical dependence to tramadol. Increased tramadol exposure can result in increased or prolonged therapeutic effects and increased risk for serious adverse events including seizures and serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Ceritinib: (Major) Avoid coadministration of ceritinib with fluoxetine if possible due to the risk of QT prolongation. If concomitant use is unavoidable, periodically monitor ECGs and electrolytes; an interruption of ceritinib therapy, dose reduction, or discontinuation of therapy may be necessary if QT prolongation occurs. Ceritinib causes concentration-dependent prolongation of the QT interval. QT prolongation and torsade de pointes (TdP) have also been reported in patients treated with fluoxetine.
Cevimeline: (Moderate) Monitor for an increase in cevimeline-related adverse effects if concomitant use of fluoxetine is necessary. Concomitant use may increase cevimeline exposure. Cevimeline is a CYP2D6 substrate; fluoxetine is a strong CYP2D6 inhibitor.
Chlordiazepoxide: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including chlordiazepoxide. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed.
Chlordiazepoxide; Amitriptyline: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including chlordiazepoxide. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed. (Moderate) Monitor for signs and symptoms of serotonin syndrome, particularly during treatment initiation and dosage increase, during concomitant amitriptyline and fluoxetine use. If serotonin syndrome occurs, discontinue therapy. Concomitant use increases the risk for serotonin syndrome.
Chlordiazepoxide; Clidinium: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including chlordiazepoxide. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed.
Chloroquine: (Major) Concomitant use of chloroquine and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Chlorothiazide: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Chlorpheniramine; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6.
Chlorpheniramine; Dextromethorphan: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of dihydrocodeine and fluoxetine because of the potential risk of serotonin syndrome, reduced dihydrocodeine efficacy, and potential for opioid withdrawal symptoms. Discontinue dihydrocodeine if serotonin syndrome is suspected. Concomitant use may increase dihydrocodeine plasma concentrations, but decrease the plasma concentration of the active metabolite, dihydromorphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of dihydrocodeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease dihydrocodeine plasma concentrations and increase dihydromorphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Dihydrocodeine is primarily metabolized by CYP2D6 to dihydromorphine, and by CYP3A4. Fluoxetine is a strong inhibitor of CYP2D6.
Chlorpheniramine; Hydrocodone: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Chlorpromazine: (Major) Fluoxetine is associated with a possible risk of QT prolongation and torsade de pointes (TdP) and chlorpromazine also has an established risk of QT prolongation and TdP. Combination therapy with these agents should be avoided if possible. Fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum phenothiazine concentrations, which may lead to phenothiazine-related side effects such as cardiac side effects, hypotension, CNS sedation, or extrapyramidal symptoms. The effects of fluoxetine on hepatic metabolism of interacting drugs may persist for a time after discontinuation of fluoxetine because of its long elimination half-life.
Chlorthalidone: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Chlorthalidone; Clonidine: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Choline Salicylate; Magnesium Salicylate: (Moderate) Monitor for signs and symptoms of bleeding during concomitant magnesium salicylate and selective serotonin reuptake inhibitor (SSRI) use due to increased risk for bleeding. Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding. (Moderate) The combined use of selective serotonin reuptake inhibitors (SSRIs) and aspirin, ASA or other salicylates which affect hemostasis may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation. A cohort study in > 26,000 patients found that SSRI use alone increased the risk for serious GI bleed by 3.6-fold; when an SSRI was combined with aspirin the risk was increased by > 5-fold. The absolute risk of GI bleed from concomitant therapy with aspirin and a SSRI was low (20/2640 patients) in this cohort study and the clinician may determine that the combined use of these drugs is appropriate.
Cilostazol: (Major) Cilostazol is extensively metabolized by the CYP3A4 hepatic isoenzyme and appears to have pharmacokinetic interactions with many medications that are potent inhibitors of CYP3A4, including fluoxetine. These agents have been shown to increase both cilostazol AUC and Cmax when administered concurrently. When significant CYP3A4 inhibitors, such as fluoxetine, are administered concomitantly with cilostazol, the manufacturer recommends that the cilostazol dosage be reduced by 50%.
Cimetidine: (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with cimetidine. Concomitant use may increase fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and cimetidine is a weak CYP2D6 inhibitor.
Cinacalcet: (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with cinacalcet. Concomitant use may increase fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and cinacalcet is a moderate CYP2D6 inhibitor.
Ciprofloxacin: (Moderate) Concomitant use of ciprofloxacin and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Cisapride: (Contraindicated) Cisapride is metabolized by CYP3A4 isozyme, a pathway that fluoxetine is known to inhibit, and may inhibit the clearance of and potentiate the toxicity of cisapride. QT prolongation and ventricular arrhythmias, including torsade de pointes and death, have been reported when inhibitors of CYP3A4 are coadministered with cisapride. Due to the serious nature of cisapride toxicity, fluoxetine should be avoided in these patients.
Citalopram: (Contraindicated) Due to the similarity in pharmacology of fluoxetine and citalopram and the potential for serious adverse reactions, including serotonin syndrome, these selective serotonin reuptake inhibitors (SSRIs) should not be administered together. Also, both fluoxetine and citalopram have been associated with QT prolongation and torsade de pointes (TdP). It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SSRI to another SSRI.
Clarithromycin: (Major) Concomitant use of clarithromycin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Clobazam: (Moderate) A dosage reduction of clobazam and/or fluoxetine may be necessary during co-administration of clobazam and fluoxetine. Metabolism of N-desmethylclobazam, the active metabolite of clobazam, occurs primarily through CYP2C19 and fluoxetine is an inhibitor of CYP2C19. Extrapolation from pharmacogenomic data indicates that concurrent use of clobazam with moderate or potent inhibitors of CYP2C19 may result in up to a 5-fold increase in exposure to N-desmethylclobazam. Adverse effects, such as sedation, lethargy, ataxia, or insomnia may be potentiated. In addition, fluoxetine is a substrate of CYP2D6 and limited in vivo data suggest that clobazam is an inhibitor of CYP2D6. A dosage reduction of CYP2D6 substrates may be necessary during co-administration of clobazam. It should be noted that because fluoxetine is metabolized by multiple enzyme systems, inhibition of one pathway may not appreciably decrease its clearance.
Clofazimine: (Moderate) Concomitant use of clofazimine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Clomipramine: (Moderate) Coadministration of fluoxetine and clomipramine may increase the risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. If serotonin syndrome is suspected, discontinue fluoxetine and concurrent serotonergic agents and initiate appropriate medical treatment. QT prolongation and TdP have been reported in patients treated with fluoxetine. Tricyclics, particularly at elevated concentrations, are associated with a possible risk of QT prolongation and TdP.
Clopidogrel: (Moderate) Monitor for bleeding and reduced clopidogrel efficacy during concomitant use of fluoxetine. Since selective serotonin reuptake inhibitors (SSRIs) affect platelet activation, the concomitant administration of SSRIs with clopidogrel may increase the risk of bleeding. Clopidogrel is primarily metabolized to its active metabolite by CYP2C19; fluoxetine is a CYP2C19 inhibitor.
Clorazepate: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including clorazepate. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed.
Clozapine: (Moderate) Consider a clozapine dose reduction if coadministered with fluoxetine and monitor for adverse reactions including QT prolongation. If fluoxetine is discontinued, monitor for lack of clozapine effect and increase dose if necessary. Modest (less than 2-fold) elevations in concentrations of clozapine and its metabolites have been reported during concurrent use of fluoxetine. Clozapine is a CYP2D6 substrate that has been associated with QT prolongation, torsade de pointes (TdP), cardiac arrest, and sudden death. Fluoxetine is a strong CYP2D6 inhibitor; QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine.
Cobicistat: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Cobimetinib: (Major) If concurrent use of cobimetinib and fluoxetine is necessary, use caution and monitor for increased cobimetinib-related adverse effects. Cobimetinib is a CYP3A substrate in vitro, and fluoxetine is a weak inhibitor of CYP3A. In healthy subjects (n = 15), coadministration of a single 10 mg dose of cobimetinib with itraconazole (200 mg once daily for 14 days), a strong CYP3A4 inhibitor, increased the mean cobimetinib AUC by 6.7-fold (90% CI, 5.6 to 8) and the mean Cmax by 3.2-fold (90% CI, 2.7 to 3.7). Simulations showed that predicted steady-state concentrations of cobimetinib at a reduced dose of 20 mg administered concurrently with short-term (less than 14 days) treatment of a moderate CYP3A inhibitor were similar to observed steady-state concentrations of cobimetinib 60 mg alone. The manufacturer of cobimetinib recommends avoiding coadministration with moderate to strong CYP3A inhibitors, and significantly reducing the dose of cobimetinib if coadministration with moderate CYP3A inhibitors cannot be avoided. Guidance is not available regarding concomitant use of cobimetinib with weak CYP3A inhibitors.
Cocaine: (Major) Concomitant use of cocaine with drugs that have CNS serotonergic properties, such as SSRIs, could potentiate serotonin neurotransmission, and result in the serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions. Additionally, citalopram causes dose-dependent QT interval prolongation. Local anesthetics (e.g., cocaine) are associated with a possible risk for QT prolongation and according to the manufacturer of citalopram, concurrent use of citalopram with other drugs that prolong the QT interval is not recommended. If concurrent therapy is considered essential, ECG monitoring is recommended.
Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6.
Codeine; Guaifenesin: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6.
Codeine; Phenylephrine; Promethazine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6. (Moderate) Concomitant use of promethazine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Codeine; Promethazine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and fluoxetine because of the potential risk of serotonin syndrome, reduced codeine efficacy, and potential for opioid withdrawal symptoms. Discontinue codeine if serotonin syndrome is suspected. It is recommended to avoid this combination when codeine is being used for cough. Concomitant use may increase codeine plasma concentrations, but decrease the plasma concentration of the active metabolite, morphine, resulting in reduced efficacy or symptoms of opioid withdrawal. Monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of fluoxetine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If fluoxetine is discontinued, monitor the patient carefully and consider reducing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Fluoxetine is a strong inhibitor of CYP2D6. (Moderate) Concomitant use of promethazine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Conjugated Estrogens: (Moderate) Estrogens are partially metabolized by CYP3A4. Drugs that inhibit CYP3A4 such as fluoxetine may increase plasma concentrations of estrogens and cause estrogen-related side effects such as nausea and breast tenderness. Patients receiving estrogens should be monitored for an increase in adverse events.
Conjugated Estrogens; Bazedoxifene: (Moderate) Estrogens are partially metabolized by CYP3A4. Drugs that inhibit CYP3A4 such as fluoxetine may increase plasma concentrations of estrogens and cause estrogen-related side effects such as nausea and breast tenderness. Patients receiving estrogens should be monitored for an increase in adverse events.
Conjugated Estrogens; Medroxyprogesterone: (Moderate) Estrogens are partially metabolized by CYP3A4. Drugs that inhibit CYP3A4 such as fluoxetine may increase plasma concentrations of estrogens and cause estrogen-related side effects such as nausea and breast tenderness. Patients receiving estrogens should be monitored for an increase in adverse events.
Crizotinib: (Major) Avoid coadministration of crizotinib with fluoxetine due to the risk of QT prolongation. If concomitant use is unavoidable, monitor ECGs for QT prolongation and monitor electrolytes. An interruption of therapy, dose reduction, or discontinuation of therapy may be necessary for crizotinib if QT prolongation occurs. Crizotinib has been associated with concentration-dependent QT prolongation. Prolongation of the QT interval and torsade de pointes (TdP) have also been reported in patients treated with fluoxetine.
Cyclobenzaprine: (Major) Because of the potential risk and severity of serotonin syndrome, concurrent use of cyclobenzaprine with other drugs that have serotonergic properties, such as the selective serotonin reuptake inhibitors (SSRIs), should generally be avoided. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, milnacipran and concurrent serotonergic agents should be discontinued.
Cyclosporine: (Moderate) Fluoxetine is a CYP3A4 inhibitor and may decrease the clearance of cyclosporine, with the potential to cause cyclosporine toxicity, including nephrotoxicity or seizures, or require the downward dosage adjustment of cyclosporine.
Cyproheptadine: (Moderate) Cyproheptadine is a serotonin antagonist in the CNS and can oppose the pharmacologic actions of selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine. Cyproheptadine has been used for the management of orgasm dysfunction caused by the SSRIs and for the adjunctive treatment of SSRI overdose (i.e., serotonin syndrome) in emergency situations; however, a reversal of antidepressant effects may occur when cyproheptadine is given in a routine manner along with the SSRIs due to the serotonin antagonistic effects of cyproheptadine. Cyproheptadine reportedly has interfered with the antidepressant and anti-bulimia actions of fluoxetine but more data are needed to confirm a direct drug-drug interaction.
Dabigatran: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like dabigatran. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Dalteparin: (Moderate) Monitor for signs and symptoms of bleeding during concomitant low molecular weight heparin and selective serotonin reuptake inhibitor (SSRI) use due to increased risk for bleeding. Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding. Altered anticoagulant effects, including increased bleeding, have been reported when SSRIs are coadministered with another anticoagulant.
Dapagliflozin: (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Dapagliflozin; Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Dapagliflozin; Saxagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Darifenacin: (Moderate) Fluoxetine inhibits CYP2D6 and CYP3A4. Serum concentrations of darifenacin, a CYP2D6 and CYP3A4 substrate, may increase when used in combination with fluoxetine. Patients should be monitored for increased anticholinergic effects if these drugs are coadministered.
Darunavir; Cobicistat: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Major) Coadministration of dasabuvir; ombitasvir; paritaprevir; ritonavir and fluoxetine should be undertaken cautiously and with careful monitoring; a dose reduction of fluoxetine may be necessary. Both fluoxetine and ritonavir have been associated with dose-related QT prolongation, and coadministration can result in elevated concentrations of both fluoxetine and ritonavir. Neurologic adverse events have also been reported when ritonavir was concurrently administered with fluoxetine. Fluoxetine is primarily metabolized by CYP2D6; ritonavir is a CYP2D6 inhibitor. Ritonavir is a substrate for CYP2D6 and CYP3A4; fluoxetine potently inhibits CYP2D6 and CYP3A4 to a lesser degree. In addition, paritaprevir and dasabuvir (minor) are metabolized by CYP3A4; therefore, their concentrations may also be affected by coadministration. (Major) Coadministration of dasabuvir; ombitasvir; paritaprevir; ritonavir or ombitasvir; paritaprevir; ritonavir and fluoxetine should be undertaken cautiously and with careful monitoring; a dose reduction of fluoxetine may be necessary. Both fluoxetine and ritonavir have been associated with dose-related QT prolongation, and coadministration can result in elevated concentrations of both fluoxetine and ritonavir. Neurologic adverse events have also been reported when ritonavir was concurrently administered with fluoxetine. Fluoxetine is primarily metabolized by CYP2D6; ritonavir is a CYP2D6 inhibitor. Ritonavir is a substrate for CYP2D6 and CYP3A4; fluoxetine potently inhibits CYP2D6 and CYP3A4 to a lesser degree. In addition, paritaprevir and dasabuvir (minor) are metabolized by CYP3A4; therefore, their concentrations may also be affected by coadministration. (Moderate) A dose reduction of fluoxetine may ne necessary if coadministered with ritonavir. Increased fluoxetine exposure may occur. Cardiac and neurologic events have been reported when ritonavir has been administered with fluoxetine.
Dasatinib: (Moderate) Concomitant use of fluoxetine and dasatinib may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Degarelix: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., degarelix) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Delavirdine: (Minor) Delavirdine is metabolized by CYP2D6 and CYP3A4. Fluoxetine impairs both of these pathways at therapeutic doses. This interaction can result in substantial increases in the trough levels of delavirdine, up to a 50% increase.
Desflurane: (Major) Concomitant use of halogenated anesthetics and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Desipramine: (Moderate) Coadministration of fluoxetine and desipramine may increase the risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. If serotonin syndrome is suspected, discontinue fluoxetine and concurrent serotonergic agents and initiate appropriate medical treatment. QT prolongation and TdP have been reported in patients treated with fluoxetine. Tricyclics, particularly at elevated concentrations, are associated with a possible risk of QT prolongation and TdP.
Desmopressin: (Minor) Additive hyponatremic effects may be seen in patients treated with desmopressin and drugs associated with water intoxication, hyponatremia, or SIADH including SSRIs. Use combination with caution, and monitor patients for signs and symptoms of hyponatremia, which may include monitoring serum sodium or electrolytes periodically. Ensure the patient is compliant with fluid restrictions and intake.
Desvenlafaxine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of fluoxetine may be necessary during concurrent use of desvenlafaxine; the dose of CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
Deutetrabenazine: (Moderate) Do not exceed 18 mg/dose or 36 mg/day of deutetrabenazine if must use concurrently with a strong CYP2D6 inhibitor, such as fluoxetine. Fluoxetine is a strong CYP2D6 inhibitor, and the metabolites of deutetrabenazine, alpha- and beta-HTBZ, are CYP2D6 substrates. The systemic exposure of alpha- and beta-HTBZ may be increased resulting in an increase in deutetrabenazine-related adverse reactions, like QT prolongation and drowsiness. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. Deutetrabenazine may prolong the QT interval, but the degree of QT prolongation is not clinically significant when deutetrabenazine is administered within the recommended dosage range.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Dextromethorphan: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Dextromethorphan; Bupropion: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold. (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with bupropion. Concomitant use may increase fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and bupropion is a strong CYP2D6 inhibitor.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Dextromethorphan; Guaifenesin: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Dextromethorphan; Guaifenesin; Potassium Guaiacolsulfonate: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Dextromethorphan; Quinidine: (Contraindicated) Concurrent use of either quinidine or dextromethorphan; quinidine and fluoxetine is considered a contraindication. Quinidine and dextromethorphan; quinidine are contraindicated for use in patients taking drugs that prolong the QT interval and are metabolized by CYP2D6. Fluoxetine is a primary substrate of CYP2D6, and is associated with a risk of QT prolongation and torsade de pointes (TdP). (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Diazepam: (Moderate) Monitor for an increase in diazepam-related adverse reactions, including sedation and respiratory depression, if coadministration with fluoxetine is necessary. Concurrent use may increase diazepam exposure. Diazepam is a CYP2C19 substrate and fluoxetine is a CYP2C19 inhibitor.
Dienogest; Estradiol valerate: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Diethylpropion: (Major) Phentermine and diethylpropion have a similar mechanism of action. When phentermine was given with fluoxetine, adrenergic excess and dyskinesia were observed. Thus, diethylpropion may interact with fluoxetine similarly. It is unclear, however, if all SSRIs would be affected as fluoxetine has the longest half-life of the group.
Dihydroergotamine: (Moderate) Use fluoxetine and ergot alkaloids together with caution due to a potential for serotonin syndrome. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with SSRIs, which may be indicative of serotonin excess. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
Dipeptidyl Peptidase-4 Inhibitors: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Diphenoxylate; Atropine: (Moderate) Concurrent administration of diphenoxylate/difenoxin with fluoxetine can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration.
Dipyridamole: (Moderate) Platelet aggregation may be impaired by SSRIs due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving platelet inhibitors. Monitor for signs and symptoms of bleeding.
Disopyramide: (Major) Because QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine, the manufacturer recommends caution when using fluoxetine with other drugs that prolong the QT interval, including disopyramide. In addition, CYP3A4 inhibitors, such as fluoxetine may increase serum plasma concentrations of disopyramide, a CYP3A4 substrate. Monitor clinical response and serum disopyramide concentrations.
Diuretics: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Docetaxel: (Minor) Docetaxel is metabolized by cytochrome P450 3A enzymes. Drugs that inhibit the CYP3A enzymes, such as fluoxetine, can significantly reduce the metabolism of docetaxel.
Dofetilide: (Major) Coadministration of dofetilide and fluoxetine is not recommended as concurrent use may increase the risk of QT prolongation and torsade de pointes (TdP). QT prolongation and TdP have been reported in patients treated with fluoxetine. Dofetilide, a Class III antiarrhythmic agent, is associated with a well-established risk of QT prolongation and TdP. The use of dofetilide with other drugs that prolong the QT interval has not been studied and is not recommended.
Dolasetron: (Moderate) Concomitant use of fluoxetine and dolasetron may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Dolutegravir; Rilpivirine: (Moderate) Concomitant use of fluoxetine and rilpivirine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. The degree of QT prolongation associated with rilpivirine is not clinically significant when administered within the recommended dosage range; QT prolongation has been described at 3 times the maximum recommended dose.
Donepezil: (Moderate) Monitor for evidence of QT prolongation and increased cholinergic effects if coadministration of donepezil and fluoxetine is necessary. Both donepezil and fluoxetine have been associated with QT prolongation and torsade de pointes (TdP). Additive effects on the QT interval are possible with concurrent use. Additionally, fluoxetine is a potent inhibitor of CYP2D6 and its metabolite is a moderate inhibitor of CYP3A4; donepezil is metabolized by CYPY2D6 and CYP3A4. Concurrent use may lead to increased plasma levels of donepezil. An increased incidence of cholinergic-related side effects may occur.
Donepezil; Memantine: (Moderate) Monitor for evidence of QT prolongation and increased cholinergic effects if coadministration of donepezil and fluoxetine is necessary. Both donepezil and fluoxetine have been associated with QT prolongation and torsade de pointes (TdP). Additive effects on the QT interval are possible with concurrent use. Additionally, fluoxetine is a potent inhibitor of CYP2D6 and its metabolite is a moderate inhibitor of CYP3A4; donepezil is metabolized by CYPY2D6 and CYP3A4. Concurrent use may lead to increased plasma levels of donepezil. An increased incidence of cholinergic-related side effects may occur.
Dorzolamide; Timolol: (Moderate) Monitor for signs of bradycardia or heart block if coadministration of timolol with fluoxetine is necessary. Concomitant use may enhance the beta-blocking properties of timolol resulting in further slowing of the heart rate or cardiac conduction. Timolol is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor.
Doxepin: (Moderate) Monitor for signs and symptoms of serotonin syndrome, particularly during treatment initiation and dosage increase, during concomitant doxepin and fluoxetine use. If serotonin syndrome occurs, discontinue therapy. Concomitant use increases the risk for serotonin syndrome.
Doxercalciferol: (Moderate) Doxercalciferol is converted in the liver to 1,25-dihydroxyergocalciferol, the major active metabolite, and 1-alpha, 24-dihydroxyvitamin D2, a minor metabolite. Although not specifically studied, cytochrome P450 enzyme inhibitors, including selective serotonin reuptake inhibitors (SSRIs), may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if SSRIs are coadministered with doxercalciferol.
Dronabinol: (Moderate) Use caution if coadministration of dronabinol with fluoxetine is necessary, and monitor for an increase in dronabinol-related adverse reactions (e.g., feeling high, dizziness, confusion, somnolence). Dronabinol is a CYP2C9 and 3A4 substrate; fluoxetine is a weak inhibitor of CYP2C9 and 3A4. Concomitant use may result in elevated plasma concentrations of dronabinol. A hypomanic episode was reported in a 21 year old female with depression and bulimia receiving fluoxetine 20 mg per day for 4 weeks after smoking marijuana. Her symptoms resolved in 4 days. Because dronabinol, THC is a synthetic analog of a naturally occurring substance found in marijuana, interactions with fluoxetine may also occur with dronabinol.
Dronedarone: (Contraindicated) Avoid concomitant use of fluoxetine and dronedarone due to an increased risk for torsade de pointes (TdP) and QT/QTc prolongation.
Droperidol: (Major) Droperidol should not be used in combination with any drug known to have potential to prolong the QT interval, such as fluoxetine. If coadministration cannot be avoided, use extreme caution; initiate droperidol at a low dose and increase the dose as needed to achieve the desired effect. Droperidol administration is associated with an established risk for QT prolongation and torsade de pointes (TdP). Some cases have occurred in patients with no known risk factors for QT prolongation and some cases have been fatal. QT prolongation and TdP have been reported in patients treated with fluoxetine.
Drospirenone; Estradiol: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Minor) Levomefolate and fluoxetine should be used together cautiously. Fluoxetine is a noncompetitive inhibitor of levomefolate active transport in the intestines. Monitor patients for decreased efficacy of levomefolate if these agents are used together.
Dulaglutide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Duloxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as duloxetine.
Dutasteride; Tamsulosin: (Moderate) Use caution if coadministration of fluoxetine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Edoxaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like edoxaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Efavirenz: (Moderate) Concomitant use of fluoxetine and efavirenz may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Efavirenz; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Concomitant use of fluoxetine and efavirenz may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Moderate) Concomitant use of fluoxetine and efavirenz may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Elagolix; Estradiol; Norethindrone acetate: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Elbasvir; Grazoprevir: (Moderate) Administering elbasvir; grazoprevir with fluoxetine may cause the plasma concentrations of elbasvir and grazoprevir to increase; thereby increasing the potential for adverse effects (i.e., elevated ALT concentrations and hepatotoxicity). Fluoxetine is a mild inhibitor of CYP3A; both elbasvir and grazoprevir are metabolized by CYP3A. If these drugs are used together, closely monitor for signs of hepatotoxicity.
Eletriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering eletriptan with fluoxetine. Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and selective serotonin reuptake inhibitors (SSRIs). Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly after a dose increase of the SSRI or the addition of other serotonergic medications to an existing SSRI regimen. Discontinue fluoxetine and eletriptan and initiate symptomatic treatment if serotonin syndrome occurs.
Elexacaftor; tezacaftor; ivacaftor: (Minor) Although an interaction between ivacaftor and fluoxetine is possible, the clinical impact of this interaction has not yet been determined. Increased monitoring is recommended if ivacaftor is administered concurrently with CYP2C9 substrates. Fluoxetine is partially metabolized by CYP2C9, but it is also a substrate for at least 2 other enzymes. In vitro studies showed ivacaftor to be a weak inhibitor of CYP2C9. Co-administration may possibly lead to increased exposure to fluoxetine; however, because fluoxetine has multiple metabolic pathways, the clinical impact of this inhibition is not clear. In addition, ivacaftor is a CYP3A substrate, and fluoxetine is a mild CYP3A inhibitor. Co-administration may lead to increased ivacaftor exposure.
Eliglustat: (Major) In poor CYP2D6 metabolizers (PMs), coadministration of fluoxetine and eliglustat is not recommended. In extensive or intermediate CYP2D6 metabolizers (EMs or IMs), concurrent use of these agents requires dosage reduction of eliglustat to 84 mg PO once daily; monitor patients closely and consider reducing the dosage of fluoxetine and titrating to clinical effect. Coadministration of eliglustat with both fluoxetine and a strong or moderate CYP3A inhibitor is contraindicated in all patients. Fluoxetine is a substrate and strong inhibitor of CYP2D6 and a weak inhibitor of CYP3A that is independently associated with QT prolongation and torsade de pointes (TdP). Eliglustat is a substrate and inhibitor of CYP2D6 and a CYP3A substrate that is predicted to cause PR, QRS, and/or QT prolongation at significantly elevated plasma concentrations. Coadministration of fluoxetine and eliglustat may result in additive effects on the QT interval and, potentially, increased plasma concentrations of one or both drugs, further increasing the risk of serious adverse events (e.g., QT prolongation and cardiac arrhythmias). Because CYP3A plays a significant role in the metabolism of eliglustat in CYP2D6 PMs, coadministration with even weak CYP3A inhibitors, such as fluoxetine, in this population may significantly increase eliglustat exposure and, hence, concurrent use is not recommended.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Empagliflozin: (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Empagliflozin; Linagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Empagliflozin; Linagliptin; Metformin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Empagliflozin; Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Moderate) Concomitant use of fluoxetine and rilpivirine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. The degree of QT prolongation associated with rilpivirine is not clinically significant when administered within the recommended dosage range; QT prolongation has been described at 3 times the maximum recommended dose.
Emtricitabine; Rilpivirine; Tenofovir Disoproxil Fumarate: (Moderate) Concomitant use of fluoxetine and rilpivirine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. The degree of QT prolongation associated with rilpivirine is not clinically significant when administered within the recommended dosage range; QT prolongation has been described at 3 times the maximum recommended dose.
Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Encainide: (Moderate) Fluoxetine is a potent inhibitor of the hepatic CYP2D6 isoenzyme. Inhibition of CYP2D6 can result in increased concentrations of antiarrhythmic drugs metabolized via the same pathway, including encainide. Increased plasma antiarrhythmic drug concentrations may increase the risk of proarrhythmias.
Encorafenib: (Major) Avoid coadministration of encorafenib and fluoxetine due to increased encorafenib exposure and QT prolongation. If concurrent use cannot be avoided, reduce the encorafenib dose to one-half of the dose used prior to the addition of fluoxetine. Monitor ECGs for QT prolongation and monitor electrolytes; correct hypokalemia and hypomagnesemia prior to treatment. If fluoxetine is discontinued, the original encorafenib dose may be resumed after 3 to 5 elimination half-lives of fluoxetine. Encorafenib is a CYP3A4 substrate that has been associated with dose-dependent QT prolongation. Fluoxetine is a weak CYP3A4 inhibitor, but the norfluoxetine metabolite is a moderate CYP3A4 inhibitor; QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. Coadministration of a moderate CYP3A4 inhibitor with a single 50 mg dose of encorafenib (0.1 times the recommended dose) increased the encorafenib AUC and Cmax by 2-fold and 45%, respectively.
Enoxaparin: (Moderate) Monitor for signs and symptoms of bleeding during concomitant low molecular weight heparin and selective serotonin reuptake inhibitor (SSRI) use due to increased risk for bleeding. Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding. Altered anticoagulant effects, including increased bleeding, have been reported when SSRIs are coadministered with another anticoagulant.
Entrectinib: (Major) Concomitant use of entrectinib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Eptifibatide: (Moderate) Platelet aggregation may be impaired by SSRIs due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving platelet inhibitors. Monitor for signs and symptoms of bleeding.
Ergoloid Mesylates: (Moderate) Use fluoxetine and ergot alkaloids together with caution due to a potential for serotonin syndrome. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with SSRIs, which may be indicative of serotonin excess. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
Ergonovine: (Moderate) Use fluoxetine and ergot alkaloids together with caution due to a potential for serotonin syndrome. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with SSRIs, which may be indicative of serotonin excess. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
Ergot alkaloids: (Moderate) Use fluoxetine and ergot alkaloids together with caution due to a potential for serotonin syndrome. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with SSRIs, which may be indicative of serotonin excess. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
Ergotamine: (Moderate) Use fluoxetine and ergot alkaloids together with caution due to a potential for serotonin syndrome. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with SSRIs, which may be indicative of serotonin excess. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
Ergotamine; Caffeine: (Moderate) Use fluoxetine and ergot alkaloids together with caution due to a potential for serotonin syndrome. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with SSRIs, which may be indicative of serotonin excess. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
Eribulin: (Moderate) Concomitant use of fluoxetine and eribulin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Ertugliflozin: (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Ertugliflozin; Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Ertugliflozin; Sitagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Erythromycin: (Major) Concomitant use of erythromycin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Escitalopram: (Major) Due to the similarity in pharmacology of fluoxetine and escitalopram and the potential for serious adverse reactions, including serotonin syndrome, these selective serotonin reuptake inhibitors (SSRIs) should not be administered together. Also, both fluoxetine and escitalopram have been associated with QT prolongation and torsade de pointes (TdP), which could theoretically result in additive effects on the QT interval. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SSRI to another SSRI.
Esomeprazole: (Minor) Fluoxetine may inhibit the CYP2C19 isoenzyme, leading to increased plasma levels of drugs that are substrates for the CYP2C19 isoenzyme, such as esomeprazole.
Esterified Estrogens: (Minor) Estrogens are partially metabolized by CYP3A4. Drugs that inhibit CYP3A4 such as fluoxetine may increase plasma concentrations of estrogens and cause estrogen-related side effects such as nausea and breast tenderness. Patients receiving estrogens should be monitored for an increase in adverse events.
Esterified Estrogens; Methyltestosterone: (Minor) Estrogens are partially metabolized by CYP3A4. Drugs that inhibit CYP3A4 such as fluoxetine may increase plasma concentrations of estrogens and cause estrogen-related side effects such as nausea and breast tenderness. Patients receiving estrogens should be monitored for an increase in adverse events.
Estradiol Cypionate; Medroxyprogesterone: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Estradiol: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Estradiol; Levonorgestrel: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Estradiol; Norethindrone: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Estradiol; Norgestimate: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Estradiol; Progesterone: (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Estropipate: (Minor) Estrogens are partially metabolized by CYP3A4. Drugs that inhibit CYP3A4 such as fluoxetine may increase plasma concentrations of estrogens and cause estrogen-related side effects such as nausea and breast tenderness. Patients receiving estrogens should be monitored for an increase in adverse events.
Eszopiclone: (Moderate) Patients should be advised of the potential for next-day psychomotor and/or memory impairment during co-administration of eszopiclone and CYP3A4 inhibitors, such as fluoxetine or fluvoxamine. CYP3A4 is a primary metabolic pathway for eszopiclone, and increased systemic exposure to eszopiclone increases the risk of next-day impairment, which may decrease the ability to perform tasks requiring full mental alertness such as driving.
Ethacrynic Acid: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Minor) Levomefolate and fluoxetine should be used together cautiously. Fluoxetine is a noncompetitive inhibitor of levomefolate active transport in the intestines. Monitor patients for decreased efficacy of levomefolate if these agents are used together.
Everolimus: (Moderate) Monitor everolimus whole blood trough concentrations as appropriate and watch for everolimus-related adverse reactions if coadministration with fluoxetine is necessary. The dose of everolimus may need to be reduced. Everolimus is a sensitive CYP3A4 substrate and a P-glycoprotein (P-gp) substrate. Norfluoxetine, the active metabolite of fluoxetine, is a moderate CYP3A4 inhibitor. Coadministration with moderate CYP3A4/P-gp inhibitors increased the AUC of everolimus by 3.5 to 4.4-fold.
Exenatide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Fedratinib: (Major) Avoid coadministration of fedratinib with fluoxetine as concurrent use may increase fedratinib exposure; fluoxetine exposure may also increase. Fedratinib is a substrate of both CYP3A4 and CYP2C19 and a moderate CYP2D6 inhibitor; fluoxetine is an inhibitor of both CYP3A4 and CYP2C19 and a CYP2D6 substrate. The coadministration of fedratinib with agents that are both a CYP3A4 and CYP2C19 inhibitor has not been evaluated.
Felodipine: (Moderate) Fluoxetine may decrease the clearance of calcium-channel blockers, including felodipine, via inhibition of CYP3A4 metabolism.
Fenfluramine: (Major) Concomitant use of fenfluramine and fluoxetine may increase fenfluramine plasma concentrations and the risk of adverse reactions, including serotonin syndrome. Avoid concomitant use if possible and monitor for serotonin syndrome if use is necessary. If concomitant use is unavoidable, do not exceed a maximum dose of fenfluramine 20 mg/day PO if coadministered with fluoxetine and 17 mg/day PO if patient is also receiving stiripentol plus clobazam. Fenfluramine is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Coadministration with another strong CYP2D6 inhibitor increased fenfluramine overall exposure by 81% and decreased norfenfluramine overall exposure by 13%.
Fenofibric Acid: (Minor) As fenofibric acid is a mild-to-moderate inhibitor of CYP2C9 and CYP2C19; while fluoxetine is a substrate of both. Although not formally studied, co-administration may lead to increased fluoxetine plasma concentrations and toxicity. Monitor the therapeutic effect of fluoxetine during coadministration with fenofibric acid.
Fentanyl: (Moderate) If concomitant use of fentanyl and fluoxetine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Fingolimod: (Moderate) Concomitant use of fluoxetine and fingolimod may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Flecainide: (Major) Concomitant use of flecainide and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Concomitant use may also increase the exposure of flecainide, further increasing the risk of adverse effects. Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary. Flecainide is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor.
Flibanserin: (Major) The concomitant use of flibanserin and a strong CYP2C19 inhibitor or multiple weak CYP3A4 inhibitors, including fluoxetine, may increase flibanserin concentrations, which may increase the risk of flibanserin-induced adverse reactions. Therefore, patients should be monitored for hypotension, syncope, somnolence, or other adverse reactions, and the risks of combination therapy with multiple weak CYP3A4 inhibitors and flibanserin should be discussed with the patient.
Fluconazole: (Moderate) Concomitant use of fluconazole and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Fluphenazine: (Moderate) Use fluoxetine with caution in combination with fluphenazine. Coadministration may increase the risk for QT prolongation and torsade de pointes (TdP). Additionally, fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum fluphenazine concentrations, leading to side effects. QT prolongation and TdP have been reported in patients treated with fluoxetine. Fluphenazine is associated with a possible risk for QT prolongation.
Flurazepam: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including flurazepam. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed.
Fluvastatin: (Moderate) In theory, concurrent use CYP2C9 inhibitors, such as fluoxetine, and fluvastatin, a CYP2C9 substrate, may result in reduced metabolism of fluvastatin and potential for toxicity including myopathy and rhabdomyolysis.
Fluvoxamine: (Major) Due to the similarity in pharmacology of fluoxetine and fluvoxamine and the potential for serious adverse reactions, including serotonin syndrome, these selective serotonin reuptake inhibitors (SSRIs) should not be administered together. Also, both fluoxetine and fluvoxamine have been associated with QT prolongation and torsade de pointes (TdP), which could theoretically result in additive effects on the QT interval. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SSRI to another SSRI.
Fondaparinux: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like fondaparinux. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Food: (Major) Advise patients to avoid cannabis use with fluoxetine. The incidence of cannabis associated adverse effects may change following coadministration with fluoxetine. Fluoxetine is an inhibitor of CYP2C9 and CYP3A4, two isoenzymes responsible for the metabolism of cannabis's most psychoactive compound, delta-9-tetrahydrocannabinol (Delta-9-THC). When given concurrently with fluoxetine the amount of Delta-9-THC converted to the active metabolite 11-hydroxy-delta-9-tetrahydrocannabinol (11-OH-THC) may be reduced. These changes in Delta-9-THC and 11-OH-THC plasma concentrations may result in an altered cannabis adverse event profile.
Foscarnet: (Major) Concomitant use of fluoxetine and foscarnet increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Fosphenytoin: (Moderate) Monitor phenytoin concentrations during concomitant therapy with fosphenytoin and fluoxetine due to risk for phenytoin toxicity. Concomitant use may increase phenytoin concentrations. Phenytoin is a CYP2C9 and CYP2C19 substrate and fluoxetine is a CYP2C9 and CYP2C19 inhibitor.
Fostemsavir: (Moderate) Concomitant use of fluoxetine and fostemsavir may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. The degree of QT prolongation associated with fostemsavir is not clinically significant when administered within the recommended dosage range; QT prolongation has been described at 4 times the recommended daily dose.
Frovatriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering frovatriptan with selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and SSRIs. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly after a dose increase of the SSRI or the addition of other serotonergic medications to an existing SSRI regimen. Discontinue the SSRI and frovatriptan and initiate symptomatic treatment if serotonin syndrome occurs.
Furosemide: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Gefitinib: (Moderate) Monitor for an increase in gefitinib-related adverse reactions if coadministration with fluoxetine is necessary; the risk is increased in CYP2D6 poor metabolizers. Based on in vitro data, gefitinib is metabolized to O-desmethyl gefitinib by CYP2D6 and fluoxetine is a CYP2D6 inhibitor. In healthy CYP2D6 poor metabolizers, the concentration of O-desmethyl gefitinib was not measurable and mean exposure to gefitinib was 2-fold higher compared to extensive metabolizers. The impact of CYP2D6 inhibitors on gefitinib pharmacokinetics has not been evaluated; however, the manufacturer recommends precautions based on exposure in patients with poor CYP2D6 metabolism.
Gemifloxacin: (Moderate) Concomitant use of fluoxetine and gemifloxacin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Gemtuzumab Ozogamicin: (Moderate) Concomitant use of fluoxetine and gemtuzumab ozogamicin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Gilteritinib: (Major) Avoid coadministration of fluoxetine with gilteritinib if possible due to the potential for additive QT prolongation and decreased response to fluoxetine. Gilteritinib has been associated with QT prolongation. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. Coadministration has the potential for additive cardiotoxicity. Additionally, gilteritinib inhibits human 5HT2B receptor or sigma nonspecific receptors, which may reduce the effects of drugs like fluoxetine that target these receptors.
Glasdegib: (Major) Avoid coadministration of glasdegib with fluoxetine due to the potential for additive QT prolongation. If coadministration cannot be avoided, monitor patients for increased risk of QT prolongation with increased frequency of ECG monitoring. Glasdegib therapy may result in QT prolongation and ventricular arrhythmias including ventricular fibrillation and ventricular tachycardia. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine.
Glipizide; Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Glyburide; Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Goserelin: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., goserelin) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Granisetron: (Moderate) Use fluoxetine with caution in combination with granisteron as there is an increased risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. If serotonin syndrome is suspected, discontinue granisetron and concurrent serotonergic agents and initiate appropriate medical treatment. QT prolongation and TdP have been reported in patients treated with fluoxetine. Granisetron has also been associated with QT prolongation.
Guaifenesin; Hydrocodone: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Halogenated Anesthetics: (Major) Concomitant use of halogenated anesthetics and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Haloperidol: (Moderate) Use fluoxetine with caution in combination with haloperidol as concurrent use may increase the risk of QT prolongation and haloperidol-related adverse effects. Fluoxetine is a strong CYP2D6 inhibitor that has been associated with a risk of QT prolongation and torsade de pointes (TdP). Haloperidol is a CYP2D6 substrate; QT prolongation and torsade de pointes (TdP) have been observed during haloperidol treatment. Excessive doses (particularly in the overdose setting) or IV administration of haloperidol may be associated with a higher risk of QT prolongation. Mild to moderately increased haloperidol concentrations have been reported when haloperidol was given concomitantly with CYP2D6 inhibitors.
Heparin: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like heparin. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Histrelin: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., histrelin) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Homatropine; Hydrocodone: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Hydralazine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Hydrocodone: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Hydrocodone; Ibuprofen: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Hydrocodone; Pseudoephedrine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and fluoxetine because of the potential risk of serotonin syndrome and prolonged opioid adverse reactions. Discontinue hydrocodone if serotonin syndrome is suspected. It is recommended to avoid this combination when hydrocodone is being used for cough. Concomitant use of hydrocodone with fluoxetine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. Monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of fluoxetine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If fluoxetine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Fluoxetine is a strong inhibitor of CYP2D6.
Hydromorphone: (Major) Fluoxetine may inhibit the metabolism of hydromorphone. Clinicians should be alert for an exaggerated opiate response if hydromorphone is given with fluoxetine.
Hydroxychloroquine: (Major) Concomitant use of hydroxychloroquine and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Hydroxyzine: (Moderate) Concomitant use of hydroxyzine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Contraindicated) According to the manufacturer of fluoxetine, treatment initiation with fluoxetine is contraindicated in patients currently receiving intravenous (IV) methylene blue due to an increased risk of serotonin syndrome. If urgent psychiatric treatment is required, interventions other than fluoxetine (e.g., alternative medication, hospitalization) should be considered. Conversely, in patients receiving fluoxetine and requiring urgent treatment with IV methylene blue, fluoxetine should be discontinued immediately and methylene blue therapy initiated only if acceptable alternatives are not available and the potential benefits outweigh the risks. The patient should be monitored for serotonin syndrome for 5 weeks or until 24 hours after the last dose of methylene blue, whichever comes first. Fluoxetine may be re-initiated 24 hours after the last dose of methylene blue. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with a serotonergic agent may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent, in patients receiving SSRIs, serotonin/norepinephrine reuptake inhibitors, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with IV methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case describes a patient receiving citalopram who experienced agitation, restlessness, pupil dilation with sluggish response to light, myoclonic movements of the lower limbs, and brisk reflexes following an infusion of methylene blue, while another patient receiving paroxetine developed tachycardia, agitation, dystonia and abnormal eye movements. During a retrospective study of 193 surgical patients who had received a methylene blue injection, it was found that all 12 of the patients who experienced postoperative neurological sequelae had been taking a serotonin reuptake inhibitor preoperatively. One of the 12 patients experienced cardiopulmonary arrest and died. Of the remaining 181 patients who did not experience neurological sequelae, 8.8% were taking a serotonin reuptake inhibitor. Published interaction reports between IV methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. (Moderate) The combined use of selective serotonin reuptake inhibitors (SSRIs) and aspirin, ASA or other salicylates which affect hemostasis may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin.
Ibuprofen; Oxycodone: (Moderate) If concomitant use of oxycodone and fluoxetine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Ibutilide: (Major) Concomitant use of ibutilide and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Ifosfamide: (Moderate) Monitor for a decrease in the efficacy of ifosfamide if coadministration with fluoxetine is necessary. Ifosfamide is metabolized by CYP3A4 to its active alkylating metabolites. Fluoxetine is a weak CYP3A4 inhibitor, but its metabolite norfluoxetine is a moderate inhibitor of CYP3A4. Coadministration may decrease plasma concentrations of these active metabolites, decreasing the effectiveness of ifosfamide treatment.
Iloperidone: (Major) Avoid coadministration of fluoxetine and iloperidone due to the potential for additive QT prolongation and risk of torsade de pointes (TdP); iloperidone levels may also be increased. If concomitant use is necessary, reduce the iloperidone dose by one-half. If fluoxetine is discontinued, increase the iloperidone dose to the previous level. Iloperidone is a CYP2D6 substrate that has been associated with QT prolongation. Fluoxetine is a strong inhibitor of CYP2D6; QT prolongation and TdP have been reported in patients treated with fluoxetine. Coadministration of fluoxetine increased the AUC of iloperidone and its metabolite P88, by about 2- to 3-fold, and decreased the AUC of its metabolite P95 by one-half.
Imatinib: (Moderate) Agents that inhibit cytochrome P450 3A4, such as fluoxetine, may decrease imatinib, STI-571 metabolism and increase concentrations leading to toxicity.
Imipramine: (Moderate) Coadministration of fluoxetine and imipramine may increase the risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. If serotonin syndrome is suspected, discontinue fluoxetine and concurrent serotonergic agents and initiate appropriate medical treatment. QT prolongation and TdP have been reported in patients treated with fluoxetine. Tricyclics, particularly at elevated concentrations, are associated with a possible risk of QT prolongation and TdP.
Incretin Mimetics: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Indapamide: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Inotuzumab Ozogamicin: (Major) Avoid coadministration of inotuzumab ozogamicin with fluoxetine due to the potential for additive QT interval prolongation and risk of torsade de pointes (TdP). If coadministration is unavoidable, obtain an ECG and serum electrolytes prior to the start of treatment, after treatment initiation, and periodically during treatment. Inotuzumab has been associated with QT interval prolongation. QT prolongation and TdP have been reported in patients treated with fluoxetine.
Insulin Degludec; Liraglutide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Glargine; Lixisenatide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulins: (Moderate) Monitor blood glucose during concomitant insulin and fluoxetine use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Iobenguane I 123: (Major) Discontinue medications that decrease norepinephrine uptake, such as selective serotonin reuptake inhibitors (SSRIs), for at least 5 biological half-lives prior to iobenguane I 123 administration. Consider medication tapering or additional supportive therapy as appropriate to minimize the risk for precipitating SSRI withdrawal symptoms. Medications that decrease the uptake of norepinephrine can cause false negative imaging results. Increasing the dose of iobenguane I 123 will not overcome any potential uptake limiting effect of this medication.
Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Isavuconazonium: (Moderate) Concomitant use of isavuconazonium with fluoxetine may result in increased serum concentrations of isavuconazonium. Isavuconazole, the active moiety of isavuconazonium, is a sensitive substrate of the hepatic isoenzyme CYP3A4; fluoxetine is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are used together.
Isocarboxazid: (Contraindicated) Due to the risk of serotonin syndrome, monoamine oxidase inhibitors (MAOIs) intended to treat psychiatric disorders are contraindicated for use with selective serotonin reuptake inhibitors (SSRIs). MAOIs should not be used within 5 weeks of discontinuing treatment with fluoxetine or within 14 days of discontinuing treatment with other SSRIs. Conversely, SSRIs should not be initiated within 14 days of stopping an MAOI. Monitor the patient for serotonin-related effects during therapy transitions.
Isoflurane: (Major) Concomitant use of halogenated anesthetics and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Isoniazid, INH: (Major) Concurrent use of isoniazid and selective serotonin reuptake inhibitors (SSRIs) should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO. Isoniazid may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with SSRIs. Concurrent use of SSRIs and MAOIs may lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If combination therapy is necessary, patients should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Concurrent use of isoniazid and selective serotonin reuptake inhibitors (SSRIs) should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO. Isoniazid may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with SSRIs. Concurrent use of SSRIs and MAOIs may lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If combination therapy is necessary, patients should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
Isoniazid, INH; Rifampin: (Major) Concurrent use of isoniazid and selective serotonin reuptake inhibitors (SSRIs) should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO. Isoniazid may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with SSRIs. Concurrent use of SSRIs and MAOIs may lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If combination therapy is necessary, patients should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
Isradipine: (Moderate) Fluoxetine may decrease the clearance of calcium-channel blockers, including isradipine, via inhibition of CYP3A4 metabolism.
Itraconazole: (Moderate) Concomitant use of fluoxetine and itraconazole may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Ivacaftor: (Minor) Although an interaction between ivacaftor and fluoxetine is possible, the clinical impact of this interaction has not yet been determined. Increased monitoring is recommended if ivacaftor is administered concurrently with CYP2C9 substrates. Fluoxetine is partially metabolized by CYP2C9, but it is also a substrate for at least 2 other enzymes. In vitro studies showed ivacaftor to be a weak inhibitor of CYP2C9. Co-administration may possibly lead to increased exposure to fluoxetine; however, because fluoxetine has multiple metabolic pathways, the clinical impact of this inhibition is not clear. In addition, ivacaftor is a CYP3A substrate, and fluoxetine is a mild CYP3A inhibitor. Co-administration may lead to increased ivacaftor exposure.
Ivosidenib: (Major) Avoid coadministration of ivosidenib with fluoxetine due to an increased risk of QT prolongation. If concomitant use is unavoidable, monitor ECGs for QTc prolongation and monitor electrolytes; correct any electrolyte abnormalities as clinically appropriate. An interruption of therapy and dose reduction of ivosidenib may be necessary if QT prolongation occurs. Prolongation of the QTc interval and ventricular arrhythmias have been reported in patients treated with ivosidenib. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine.
Ketoconazole: (Contraindicated) Avoid concomitant use of ketoconazole and fluoextine due to an increased risk for torsade de pointes (TdP) and QT/QTc prolongation. Ketoconazole has a known risk for QT prolongation and torsade de pointes (TdP). Postmarketing cases of QT interval prolongation and ventricular arrhythmia including TdP have been reported in patients treated with fluoxetine.
Lansoprazole; Amoxicillin; Clarithromycin: (Major) Concomitant use of clarithromycin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Lapatinib: (Moderate) Concomitant use of fluoxetine and lapatinib may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Lasmiditan: (Moderate) Serotonin syndrome may occur during coadministration of lasmiditan and selective serotonin reuptake inhibitors. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly after a dose increase or the addition of other serotonergic medications to an existing regimen. Discontinue all serotonergic agents if serotonin syndrome occurs and implement appropriate medical management.
Lefamulin: (Major) Avoid coadministration of lefamulin with fluoxetine as concurrent use may increase the risk of QT prolongation. If coadministration cannot be avoided, monitor ECG during treatment. Lefamulin has a concentration dependent QTc prolongation effect. The pharmacodynamic interaction potential to prolong the QT interval of the electrocardiogram between lefamulin and other drugs that effect cardiac conduction is unknown. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine.
Lemborexant: (Major) Limit the dose of lemborexant to a maximum of 5 mg PO once daily if coadministered with fluoxetine as concurrent use may increase lemborexant exposure and the risk of adverse effects. Lemborexant is a CYP3A4 substrate; fluoxetine is a weak CYP3A4 inhibitor and one metabolite, norfluoxetine, is a moderate CYP3A4 inhibitor. Coadministration of lemborexant with a weak CYP3A4 inhibitor is predicted to increase lemborexant exposure by less than 2-fold.
Lenvatinib: (Major) Concomitant use of lenvatinib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Lesinurad: (Moderate) Use lesinurad and fluoxetine together with caution; fluoxetine may increase the systemic exposure of lesinurad. Fluoxetine is a mild inhibitor of CYP2C9, and lesinurad is a CYP2C9 substrate.
Lesinurad; Allopurinol: (Moderate) Use lesinurad and fluoxetine together with caution; fluoxetine may increase the systemic exposure of lesinurad. Fluoxetine is a mild inhibitor of CYP2C9, and lesinurad is a CYP2C9 substrate.
Leuprolide: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., leuprolide) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Leuprolide; Norethindrone: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., leuprolide) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Levofloxacin: (Moderate) Concomitant use of levofloxacin and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Levoketoconazole: (Contraindicated) Avoid concomitant use of ketoconazole and fluoextine due to an increased risk for torsade de pointes (TdP) and QT/QTc prolongation. Ketoconazole has a known risk for QT prolongation and torsade de pointes (TdP). Postmarketing cases of QT interval prolongation and ventricular arrhythmia including TdP have been reported in patients treated with fluoxetine.
Levomefolate: (Minor) Levomefolate and fluoxetine should be used together cautiously. Fluoxetine is a noncompetitive inhibitor of levomefolate active transport in the intestines. Monitor patients for decreased efficacy of levomefolate if these agents are used together.
Levomilnacipran: (Major) Because of the potential risk and severity of serotonin syndrome, concurrent use of levomilnacipran with other drugs that have serotonergic properties, such as selective serotonin reuptake inhibitors (SSRIs), should generally be avoided. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, levomilnacipran and concurrent serotonergic agents should be discontinued.
Levorphanol: (Major) Fluoxetine may inhibit the metabolism of levorphanol. Clinicians should be alert for an exaggerated opiate response if levorphanol is given with fluoxetine.
Lidocaine: (Moderate) Concomitant use of systemic lidocaine and fluoxetine may increase lidocaine plasma concentrations by decreasing lidocaine clearance and therefore prolonging the elimination half-life. Monitor for lidocaine toxicity if used together. Lidocaine is a CYP3A4 and CYP1A2 substrate; fluoxetine inhibits CYP3A4.
Lidocaine; Epinephrine: (Moderate) Concomitant use of systemic lidocaine and fluoxetine may increase lidocaine plasma concentrations by decreasing lidocaine clearance and therefore prolonging the elimination half-life. Monitor for lidocaine toxicity if used together. Lidocaine is a CYP3A4 and CYP1A2 substrate; fluoxetine inhibits CYP3A4.
Lidocaine; Prilocaine: (Moderate) Concomitant use of systemic lidocaine and fluoxetine may increase lidocaine plasma concentrations by decreasing lidocaine clearance and therefore prolonging the elimination half-life. Monitor for lidocaine toxicity if used together. Lidocaine is a CYP3A4 and CYP1A2 substrate; fluoxetine inhibits CYP3A4.
Linagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Linagliptin; Metformin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Linezolid: (Contraindicated) According to the manufacturer of fluoxetine, treatment initiation with fluoxetine is contraindicated in patients currently receiving linezolid due to an increased risk of serotonin syndrome. If urgent psychiatric treatment is required, interventions other than fluoxetine (e.g., alternative medication, hospitalization) should be considered. Conversely, in patients receiving fluoxetine and requiring urgent treatment with linezolid, fluoxetine should be discontinued immediately and linezolid therapy initiated only if acceptable alternatives are not available and the potential benefits of linezolid outweigh the risks. The patient should be monitored for serotonin syndrome for five weeks or until 24 hours after the last dose of linezolid, whichever comes first. Fluoxetine may be re-initiated 24 hours after the last dose of linezolid. Linezolid is an antibiotic that is also a non-selective monoamine oxidase (MAO) inhibitor. Since monoamine oxidase type A deaminates serotonin, administration of a non-selective MAO inhibitor concurrently with fluoxetine can lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Serotonin syndrome has been reported in patients receiving either citalopram, escitalopram, fluoxetine, or paroxetine in combination with linezolid.
Liraglutide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Lithium: (Moderate) Coadministration of fluoxetine and lithium may increase the risk for QT prolongation and serotonin syndrome. Concurrent use of fluoxetine with lithium has also resulted in both increased and decreased serum lithium concentrations; patients should be monitored closely. QT prolongation has been reported in patients treated with fluoxetine and lithium has also been associated with QT prolongation. Lithium is an effective augmenting agent to antidepressants in treatment-resistant depression; however, lithium has central serotonin-enhancing effects and may increase the risk of serotonin syndrome when combined with selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine. Inform patients of the possible increased risk and monitor for serotonin syndrome, particularly during treatment initiation and dosage increases. If serotonin syndrome occurs, serotonergic agents should be discontinued and symptomatic treatment should be initiated.
Lixisenatide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Lofexidine: (Major) Monitor ECG for QT prolongation and monitor for orthostatic hypotension and bradycardia during concurrent use of lofexidine and fluoxetine. Coadministration may increase lofexidine exposure. Lofexidine is a CYP2D6 substrate that prolongs the QT interval. In addition, there are postmarketing reports of TdP. Fluoxetine is a CYP2D6 inhibitor associated with an established risk of QT prolongation and TdP. Coadministration with a strong CYP2D6 inhibitor increased the lofexidine AUC by 28%.
Lomitapide: (Major) Concomitant use of lomitapide and fluoxetine may significantly increase the serum concentration of lomitapide. Therefore, the lomitapide dose should not exceed 30 mg/day PO during concurrent use. Fluoxetine is a weak CYP3A4 inhibitor; the exposure to lomitapide is increased by approximately 2-fold in the presence of weak CYP3A4 inhibitors.
Lonafarnib: (Major) Avoid coadministration of lonafarnib and fluoxetine; concurrent use may increase the exposure of lonafarnib and the risk of adverse effects. If coadministration is unavoidable, reduce to or continue lonafarnib at a dosage of 115 mg/m2 and closely monitor patients for lonafarnib-related adverse reactions. Resume previous lonafarnib dosage 14 days after discontinuing fluoxetine. Lonafarnib is a sensitive CYP3A4 and CYP2C9 substrate and fluoxetine is a weak CYP3A4 and CYP2C9 inhibitor.
Loperamide: (Moderate) Concomitant use of loperamide and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Loperamide; Simethicone: (Moderate) Concomitant use of loperamide and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Lopinavir; Ritonavir: (Major) Concomitant use of lopinavir and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary. (Moderate) A dose reduction of fluoxetine may ne necessary if coadministered with ritonavir. Increased fluoxetine exposure may occur. Cardiac and neurologic events have been reported when ritonavir has been administered with fluoxetine.
Lorcaserin: (Major) Based on the mechanism of action of lorcaserin and the theoretical potential for serotonin syndrome, use with extreme caution in combination with other drugs that may affect the serotonergic neurotransmitter systems, including, selective serotonin reuptake inhibitors (SSRIs). Patients receiving this combination should be monitored for the emergence of serotonin syndrome or Neuroleptic Malignant Syndrome (NMS) like signs and symptoms.
Losartan: (Minor) Inhibitors of the hepatic CYP2C9 isoenzyme, such as fluoxetine, have potential to inhibit the conversion of losartan to its active metabolite. Monitor therapeutic response to individualize losartan dosage.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia. (Minor) Inhibitors of the hepatic CYP2C9 isoenzyme, such as fluoxetine, have potential to inhibit the conversion of losartan to its active metabolite. Monitor therapeutic response to individualize losartan dosage.
Low Molecular Weight Heparins: (Moderate) Monitor for signs and symptoms of bleeding during concomitant low molecular weight heparin and selective serotonin reuptake inhibitor (SSRI) use due to increased risk for bleeding. Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding. Altered anticoagulant effects, including increased bleeding, have been reported when SSRIs are coadministered with another anticoagulant.
Lumacaftor; Ivacaftor: (Minor) Although an interaction between ivacaftor and fluoxetine is possible, the clinical impact of this interaction has not yet been determined. Increased monitoring is recommended if ivacaftor is administered concurrently with CYP2C9 substrates. Fluoxetine is partially metabolized by CYP2C9, but it is also a substrate for at least 2 other enzymes. In vitro studies showed ivacaftor to be a weak inhibitor of CYP2C9. Co-administration may possibly lead to increased exposure to fluoxetine; however, because fluoxetine has multiple metabolic pathways, the clinical impact of this inhibition is not clear. In addition, ivacaftor is a CYP3A substrate, and fluoxetine is a mild CYP3A inhibitor. Co-administration may lead to increased ivacaftor exposure.
Lumacaftor; Ivacaftor: (Minor) Concomitant use of fluoxetine and lumacaftor; ivacaftor may alter fluoxetine exposure; caution and close monitoring are advised if these drugs are used together. Fluoxetine is a substrate of CYP2C9 and CYP2C19. In vitro data suggest that lumacaftor; ivacaftor may induce CYP2C19 and induce and/or inhibit CYP2C9. Although induction of fluoxetine through the CYP2C19 pathway could potentially lead to decreased drug efficacy, the net effect of lumacaftor; ivacaftor on CYP2C9-mediated metabolism is not clear. Monitor the patient for decreased fluoxetine efficacy or increased or prolonged therapeutic effects and adverse events. Of note, norfluoxetine, the active metabolite of fluoxetine, is a moderate CYP3A inhibitor. Although lumacaftor; ivacaftor is a primary substrate of CYP3A, lumacaftor; ivacaftor dosage adjustment is not required.
Lurasidone: (Major) The metabolite of fluoxetine is a moderate CYP3A4 inhibitor and may decrease the clearance of CYP3A4 substrates such as lurasidone. Decreased metabolism of lurasidone may lead to clinically important adverse reactions that are associated with antipsychotic use, such as extrapyramidal symptoms. If a moderate inhibitor of CYP3A4 is being prescribed and lurasidone is added in an adult patient, the recommended starting dose of lurasidone is 20 mg/day and the maximum recommended daily dose of lurasidone is 80 mg/day. If a moderate CYP3A4 inhibitor is added to an existing lurasidone regimen, reduce the lurasidone dose to one-half of the original dose. Patients should be monitored for efficacy and toxicity. The effects of fluoxetine on the metabolism of interacting drugs may persist for several weeks after discontinuation of fluoxetine because of its long elimination half-life.
Macimorelin: (Major) Avoid concurrent administration of macimorelin with drugs that prolong the QT interval, such as fluoxetine. Use of these drugs together may increase the risk of developing torsade de pointes-type ventricular tachycardia. Sufficient washout time of drugs that are known to prolong the QT interval prior to administration of macimorelin is recommended. Treatment with macimorelin has been associated with an increase in the corrected QT (QTc) interval. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine.
Magnesium Salicylate: (Moderate) Monitor for signs and symptoms of bleeding during concomitant magnesium salicylate and selective serotonin reuptake inhibitor (SSRI) use due to increased risk for bleeding. Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding.
Maprotiline: (Moderate) Concomitant use of fluoxetine and maprotiline may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Maraviroc: (Minor) Use caution if coadministration of maraviroc with fluoxetine is necessary, due to a possible increase in maraviroc exposure. Maraviroc is a CYP3A substrate and fluoxetine is a weak CYP3A4 inhibitor. Monitor for an increase in adverse effects with concomitant use.
Mavacamten: (Contraindicated) Mavacamten is contraindicated for use with fluoxetine due to risk of heart failure due to systolic dysfunction. Concomitant use increases mavacamten exposure. Mavacamten is a CYP2C19 substrate and fluoxetine is a strong CYP2C19 inhibitor.
Meclizine: (Moderate) Meclizine is metabolized by CYP2D6, fluoxetine is a CYP2D6 inhibitor. Concomitant use may increase meclizine plasma concentrations which may intensify its sedative and anticholinergic effects.
Mefloquine: (Moderate) Use fluoxetine with caution in combination with mefloquine. Coadministration may increase the risk for QT prolongation and torsade de pointes (TdP). Additionally, fluoxetine may increase the systemic exposure of mefloquine due to CYP3A4 inhibition and increase the potential for mefloquine-related adverse reactions. QT prolongation and TdP have been reported in patients treated with fluoxetine. There is evidence that the use of halofantrine after mefloquine causes a significant lengthening of the QTc interval. Mefloquine alone has not been reported to cause QT prolongation. However, due to the lack of clinical data, mefloquine should be used with caution in patients receiving drugs that prolong the QT interval.
Meglitinides: (Moderate) In patients with diabetes mellitus, fluoxetine may alter glycemic control. Hypoglycemia has occurred during fluoxetine therapy. Hyperglycemia has developed in patients with diabetes mellitus following discontinuation of the drug. The dosage of insulin and/or other antidiabetic agents may need to be adjusted when therapy with fluoxetine is instituted or discontinued.
Meperidine: (Moderate) Consider a reduced dose of meperidine with frequent monitoring for respiratory depression and sedation if concurrent use of fluoxetine is necessary; if fluoxetine is discontinued, meperidine plasma concentrations can decrease resulting in reduced efficacy and potential withdrawal syndrome in a patient who has developed physical dependence to meperidine. Meperidine is a substrate of CYP3A4, and fluoxetine and its metabolite, norfluoxetine, are weak and moderate CYP3A4 inhibitors, respectively. Concomitant use with fluoxetine can increase meperidine exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of meperidine. Also monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Meperidine; Promethazine: (Moderate) Concomitant use of promethazine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. (Moderate) Consider a reduced dose of meperidine with frequent monitoring for respiratory depression and sedation if concurrent use of fluoxetine is necessary; if fluoxetine is discontinued, meperidine plasma concentrations can decrease resulting in reduced efficacy and potential withdrawal syndrome in a patient who has developed physical dependence to meperidine. Meperidine is a substrate of CYP3A4, and fluoxetine and its metabolite, norfluoxetine, are weak and moderate CYP3A4 inhibitors, respectively. Concomitant use with fluoxetine can increase meperidine exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of meperidine. Also monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Metaxalone: (Moderate) Concomitant use of selective serotonin reuptake inhibitors (SSRIs) and metaxalone may increase the risk for serotonin syndrome. Monitor patients for serotonin syndrome if concomitant use is necessary.
Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Metformin; Repaglinide: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Metformin; Rosiglitazone: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Metformin; Saxagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Metformin; Sitagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia. (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Methadone: (Major) Coadministration may increase the risk of serotonin syndrome, QT prolongation, torsade de pointes (TdP), or opioid-related side effects. QT prolongation and TdP have been reported in patients treated with fluoxetine and the manufacturer recommends caution when using fluoxetine with other drugs that prolong the QT interval. Methadone is associated with an increased risk for QT prolongation and TdP, especially at higher doses (greater than 200 mg/day but averaging approximately 400 mg/day in adult patients). Most cases involve patients being treated for pain with large, multiple daily doses of methadone, although cases have been reported in patients receiving doses commonly used for maintenance treatment of opioid addiction. In addition, both fluoxetine and methadone have central serotonergic properties and serotonin syndrome is possible. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical treatment should be implemented. Lastly, fluoxetine may inhibit the metabolism of methadone via CYP3A4 or CYP2D6. In patients treated with methadone and fluoxetine, the plasma concentration of methadone increased. Interestingly in patients treated with methadone, the R-enantiomer (the active moiety) was increased by the addition of fluoxetine. Patients may experience increases in CNS depressive effects or respiratory depression. Thus, methadone-treated patients receiving fluoxetine should be carefully monitored and dosage adjustments may be warranted.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Contraindicated) According to the manufacturer of fluoxetine, treatment initiation with fluoxetine is contraindicated in patients currently receiving intravenous (IV) methylene blue due to an increased risk of serotonin syndrome. If urgent psychiatric treatment is required, interventions other than fluoxetine (e.g., alternative medication, hospitalization) should be considered. Conversely, in patients receiving fluoxetine and requiring urgent treatment with IV methylene blue, fluoxetine should be discontinued immediately and methylene blue therapy initiated only if acceptable alternatives are not available and the potential benefits outweigh the risks. The patient should be monitored for serotonin syndrome for 5 weeks or until 24 hours after the last dose of methylene blue, whichever comes first. Fluoxetine may be re-initiated 24 hours after the last dose of methylene blue. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with a serotonergic agent may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent, in patients receiving SSRIs, serotonin/norepinephrine reuptake inhibitors, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with IV methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case describes a patient receiving citalopram who experienced agitation, restlessness, pupil dilation with sluggish response to light, myoclonic movements of the lower limbs, and brisk reflexes following an infusion of methylene blue, while another patient receiving paroxetine developed tachycardia, agitation, dystonia and abnormal eye movements. During a retrospective study of 193 surgical patients who had received a methylene blue injection, it was found that all 12 of the patients who experienced postoperative neurological sequelae had been taking a serotonin reuptake inhibitor preoperatively. One of the 12 patients experienced cardiopulmonary arrest and died. Of the remaining 181 patients who did not experience neurological sequelae, 8.8% were taking a serotonin reuptake inhibitor. Published interaction reports between IV methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma.
Methyclothiazide: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Methylene Blue: (Contraindicated) According to the manufacturer of fluoxetine, treatment initiation with fluoxetine is contraindicated in patients currently receiving intravenous (IV) methylene blue due to an increased risk of serotonin syndrome. If urgent psychiatric treatment is required, interventions other than fluoxetine (e.g., alternative medication, hospitalization) should be considered. Conversely, in patients receiving fluoxetine and requiring urgent treatment with IV methylene blue, fluoxetine should be discontinued immediately and methylene blue therapy initiated only if acceptable alternatives are not available and the potential benefits outweigh the risks. The patient should be monitored for serotonin syndrome for 5 weeks or until 24 hours after the last dose of methylene blue, whichever comes first. Fluoxetine may be re-initiated 24 hours after the last dose of methylene blue. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with a serotonergic agent may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent, in patients receiving SSRIs, serotonin/norepinephrine reuptake inhibitors, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with IV methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case describes a patient receiving citalopram who experienced agitation, restlessness, pupil dilation with sluggish response to light, myoclonic movements of the lower limbs, and brisk reflexes following an infusion of methylene blue, while another patient receiving paroxetine developed tachycardia, agitation, dystonia and abnormal eye movements. During a retrospective study of 193 surgical patients who had received a methylene blue injection, it was found that all 12 of the patients who experienced postoperative neurological sequelae had been taking a serotonin reuptake inhibitor preoperatively. One of the 12 patients experienced cardiopulmonary arrest and died. Of the remaining 181 patients who did not experience neurological sequelae, 8.8% were taking a serotonin reuptake inhibitor. Published interaction reports between IV methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma.
Methylergonovine: (Moderate) Use fluoxetine and ergot alkaloids together with caution due to a potential for serotonin syndrome. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with SSRIs, which may be indicative of serotonin excess. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
Methylphenidate Derivatives: (Moderate) Caution should be observed when coadministering methylphenidate derivatives and the selective serotonin reuptake inhibitors (SSRIs). There are postmarketing reports of serotonin syndrome during concurrent use of methylphenidate derivatives with other serotonergic medications. Human pharmacologic studies have shown that methylphenidate may inhibit the metabolism of some SSRIs and downward dose adjustment of the SSRI may be required in some patients. Inform patients of the possible increased risk and monitor for the emergence of serotonin syndrome. If serotonin syndrome occurs, serotonergic agents should be discontinued and appropriate medical management should be implemented.
Metoclopramide: (Major) When metoclopramide is used with a potent CYP2D6 inhibitor for the treatment of gastroesophageal reflux (GERD), dosage reductions of oral metoclopramide are required, with maximum oral dosage not to exceed 30 mg/day (e.g., 5 mg 4 times daily or 10 mg 3 times daily). There is a known increase in metoclopramide exposure and an increased risk for extrapyramidal adverse reactions. Metoclopramide is a substrate of CYP2D6 and fluoxetine is a strong CYP2D6 inhibitor. The manufacturer recommends avoidance of fluoxetine and consideration of alternative SSRI antidepressants when oral metoclopramide is used in patients with diabetic gastroparesis. Healthy patients given 20 mg of metoclopramide and 60 mg of fluoxetine for 8 days had a 40% and 90% increase in metoclopramide Cmax and AUC, respectively, compared to patients who received metoclopramide alone. Additionally, concomitant use of metoclopramide and SSRIs such as fluoxetine may increase the risk for serotonin syndrome. In rare cases postmarketing, NMS-like symptoms, which may overlap with serotonin syndrome symptoms, have been reported with metoclopramide when used with serotonergic agents.
Metolazone: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Metoprolol: (Moderate) Monitor for metoprolol-related adverse reactions, including bradycardia and hypotension, during coadministration with fluoxetine. Concomitant use may increase metoprolol serum concentrations which would decrease the cardioselectivity of metoprolol. Metoprolol is a CYP2D6 substrate and fluoxetine is a CYP2D6 inhibitor.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for metoprolol-related adverse reactions, including bradycardia and hypotension, during coadministration with fluoxetine. Concomitant use may increase metoprolol serum concentrations which would decrease the cardioselectivity of metoprolol. Metoprolol is a CYP2D6 substrate and fluoxetine is a CYP2D6 inhibitor. (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Metronidazole: (Moderate) Concomitant use of metronidazole and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Mexiletine: (Moderate) Fluoxetine is a potent inhibitor of the hepatic CYP2D6 isoenzyme. Inhibition of CYP2D6 can result in increased concentrations of antiarrhythmic drugs metabolized via the same pathway, including mexiletine. Increased plasma concentrations may increase the risk of proarrhythmias.
Midazolam: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including midazolam. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed.
Midostaurin: (Major) Concomitant use of midostaurin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Mifepristone: (Major) Concomitant use of mifepristone and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Miglitol: (Moderate) In patients with diabetes mellitus, fluoxetine may alter glycemic control. Hypoglycemia has occurred during fluoxetine therapy. Hyperglycemia has developed in patients with diabetes mellitus following discontinuation of the drug. The dosage of insulin and/or other antidiabetic agents may need to be adjusted when therapy with fluoxetine is instituted or discontinued.
Milnacipran: (Major) Because of the potential risk and severity of serotonin syndrome, concurrent use of milnacipran with other drugs that have serotonergic properties, such as the selective serotonin reuptake inhibitors (SSRIs), should generally be avoided. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, milnacipran and concurrent serotonergic agents should be discontinued.
Mirabegron: (Moderate) Mirabegron is a moderate CYP2D6 inhibitor. Exposure of drugs metabolized by CYP2D6 isoenzymes such as fluoxetine may be increased when co-administered with mirabegron. Fluoxetine is primarily metabolized by CYP2D6. Therefore, appropriate monitoring and dose adjustment may be necessary.
Mirtazapine: (Moderate) Use fluoxetine with caution in combination with mirtazapine. Coadministration may increase the risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. Case reports of serotonin syndrome have been reported with this combination. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical treatment should be implemented. Both drugs have been reported to cause QT prolongation and TdP.
Mobocertinib: (Major) Concomitant use of mobocertinib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Modafinil: (Moderate) Although no clinical data are available, fluoxetine may inhibit the clearance and potentiate the actions of modafinil. Modafinil is metabolized by CYP3A4 isozyme, a pathway that fluoxetine is known to inhibit.
Monoamine oxidase inhibitors: (Contraindicated) Due to the risk of serotonin syndrome, monoamine oxidase inhibitors (MAOIs) intended to treat psychiatric disorders are contraindicated for use with selective serotonin reuptake inhibitors (SSRIs). MAOIs should not be used within 5 weeks of discontinuing treatment with fluoxetine or within 14 days of discontinuing treatment with other SSRIs. Conversely, SSRIs should not be initiated within 14 days of stopping an MAOI. Monitor the patient for serotonin-related effects during therapy transitions.
Morphine: (Moderate) Serotonin syndrome can occur during concomitant use of opiate agonists like morphine with serotonergic drugs, such as fluoxetine. Symptoms may occur hours to days after concomitant use, particularly after dose increases. Serotonin syndrome may occur within recommended dose ranges. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Morphine; Naltrexone: (Moderate) Serotonin syndrome can occur during concomitant use of opiate agonists like morphine with serotonergic drugs, such as fluoxetine. Symptoms may occur hours to days after concomitant use, particularly after dose increases. Serotonin syndrome may occur within recommended dose ranges. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Moxifloxacin: (Major) Concomitant use of moxifloxacin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Nabilone: (Minor) A hypomanic episode was reported in a 21-year-old female with depression and bulimia receiving fluoxetine 20 mg/day for 4 weeks after smoking cannabis; symptoms resolved after 4 days. This interaction may also occur with nabilone which is a synthetic analog of a naturally occurring substance found in cannabis.
Nanoparticle Albumin-Bound Paclitaxel: (Moderate) Monitor for an increase in paclitaxel-related adverse reactions if coadministration of nab-paclitaxel with fluoxetine is necessary due to the risk of increased plasma concentrations of paclitaxel. Nab-paclitaxel is a CYP3A4 substrate; fluoxetine is a weak inhibitor of CYP3A4, but its metabolite norfluoxetine is a moderate CYP3A4 inhibitor. In vitro, coadministration with both strong and moderate CYP3A4 inhibitors increased paclitaxel exposure; however, the concentrations used exceeded those found in vivo following normal therapeutic doses. The pharmacokinetics of paclitaxel may also be altered in vivo as a result of interactions with CYP3A4 inhibitors.
Nanoparticle Albumin-Bound Sirolimus: (Moderate) Agents that inhibit CYP3A4 and/or P-glycoprotein, such as fluoxetine, may affect absorption and elimination of sirolimus leading to increased blood concentrations. Monitor sirolimus serum concentrations carefully if an inhibitor of CYP3A4 or P-glycoprotein needs to be used concomitantly.
Naproxen; Esomeprazole: (Minor) Fluoxetine may inhibit the CYP2C19 isoenzyme, leading to increased plasma levels of drugs that are substrates for the CYP2C19 isoenzyme, such as esomeprazole.
Naratriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering naratriptan with selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists ("triptans") and SSRIs. Inform patients of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly after initiation of SSRI treatment or any dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Nebivolol: (Major) Avoid the concomitant use of nebivolol and fluoxetine. Concomitant use may increase the exposure of nebivolol and the risk of adverse effects. Nebivolol is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Coadministration with fluoxetine caused an 8-fold increase in the AUC of d-nebivolol.
Nebivolol; Valsartan: (Major) Avoid the concomitant use of nebivolol and fluoxetine. Concomitant use may increase the exposure of nebivolol and the risk of adverse effects. Nebivolol is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Coadministration with fluoxetine caused an 8-fold increase in the AUC of d-nebivolol.
Nefazodone: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as nefazodone and fluoxetine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. At least one case report of serotonin syndrome from the concurrent use of nefazodone and a selective serotonin reuptake inhibitor (i.e., paroxetine) has been published. Additionally, when a 200 mg dose of nefazodone was administered to subjects who had been receiving fluoxetine for 1 week, there was an increased incidence of transient serotonin-related adverse events. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical treatment should be implemented.
Netupitant, Fosnetupitant; Palonosetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering palonosetron with other drugs that have serotonergic properties such as fluoxetine. If serotonin syndrome is suspected, discontinue palonosetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
Nicardipine: (Moderate) Fluoxetine may decrease the clearance of calcium-channel blockers, including nicardipine, via inhibition of CYP3A4 metabolism.
Nifedipine: (Moderate) Fluoxetine may decrease the clearance of calcium-channel blockers, including nifedipine, via inhibition of CYP3A4 metabolism.
Nilotinib: (Major) Concomitant use of nilotinib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Nimodipine: (Moderate) Fluoxetine may decrease the clearance of calcium-channel blockers, including nimodipine, via inhibition of CYP3A4 metabolism.
Nirmatrelvir; Ritonavir: (Moderate) A dose reduction of fluoxetine may ne necessary if coadministered with ritonavir. Increased fluoxetine exposure may occur. Cardiac and neurologic events have been reported when ritonavir has been administered with fluoxetine.
Nisoldipine: (Major) Avoid coadministration of nisoldipine with fluoxetine due to increased plasma concentrations of nisoldipine. If coadministration is unavoidable, monitor blood pressure closely during concurrent use of these medications. Nisoldipine is a CYP3A4 substrate and fluoxetine is a CYP3A4 inhibitor.
Nitroglycerin: (Minor) Nitroglycerin can cause hypotension. This action may be additive with other agents that can cause hypotension such as antidepressants. Patients should be monitored more closely for hypotension if nitroglycerin is used concurrently with antidepressants.
Nonsteroidal antiinflammatory drugs: (Moderate) Monitor for signs and symptoms of bleeding during concomitant selective serotonin reuptake inhibitor (SSRI) and nonsteroidal antiinflammatory drug (NSAID) use due to increased risk for bleeding. Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding.
Nortriptyline: (Moderate) Coadministration of fluoxetine and nortriptyline may increase the risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. If serotonin syndrome is suspected, discontinue fluoxetine and concurrent serotonergic agents and initiate appropriate medical treatment. QT prolongation and TdP have been reported in patients treated with fluoxetine. Tricyclics, particularly at elevated concentrations, are associated with a possible risk of QT prolongation and TdP.
Ofloxacin: (Moderate) Concomitant use of ofloxacin and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Olanzapine: (Moderate) Concomitant use of fluoxetine and olanzapine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Olanzapine; Fluoxetine: (Moderate) Concomitant use of fluoxetine and olanzapine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Olanzapine; Samidorphan: (Moderate) Concomitant use of fluoxetine and olanzapine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Oliceridine: (Moderate) Monitor patients closely for respiratory depression and sedation at frequent intervals and base subsequent doses on the patient's severity of pain and response to treatment if concomitant administration of oliceridine and fluoxetine is necessary; less frequent dosing of oliceridine may be required. Concomitant use of oliceridine and fluoxetine may increase the plasma concentration of oliceridine, resulting in increased or prolonged opioid effects; these effects may be more pronounced with fluoxetine as it can inhibit multiple CYP enzymes. If fluoxetine is discontinued, consider increasing the oliceridine dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oliceridine is a CYP3A4 and CYP2D6 substrate and fluoxetine and its metabolite, norfluoxetine, are a strong CYP2D6 inhibitor and moderate CYP3A4 inhibitor, respectively. Also monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Ombitasvir; Paritaprevir; Ritonavir: (Major) Coadministration of dasabuvir; ombitasvir; paritaprevir; ritonavir or ombitasvir; paritaprevir; ritonavir and fluoxetine should be undertaken cautiously and with careful monitoring; a dose reduction of fluoxetine may be necessary. Both fluoxetine and ritonavir have been associated with dose-related QT prolongation, and coadministration can result in elevated concentrations of both fluoxetine and ritonavir. Neurologic adverse events have also been reported when ritonavir was concurrently administered with fluoxetine. Fluoxetine is primarily metabolized by CYP2D6; ritonavir is a CYP2D6 inhibitor. Ritonavir is a substrate for CYP2D6 and CYP3A4; fluoxetine potently inhibits CYP2D6 and CYP3A4 to a lesser degree. In addition, paritaprevir and dasabuvir (minor) are metabolized by CYP3A4; therefore, their concentrations may also be affected by coadministration. (Moderate) A dose reduction of fluoxetine may ne necessary if coadministered with ritonavir. Increased fluoxetine exposure may occur. Cardiac and neurologic events have been reported when ritonavir has been administered with fluoxetine.
Ondansetron: (Major) Due to the potential for QT prolongation, cautious use and close monitoring are advisable if concurrent use of fluoxetine and ondansetron is necessary. Both medications may cause QT interval prolongation and a risk for torsade de pointes (TdP). ECG monitoring has been recommended for at-risk patients. In addition, concurrent use of ondansetron with other drugs that modulate serotonergic function, such as fluoxetine, has resulted in serotonin syndrome in some cases. Patients should be carefully observed, particularly during treatment initiation and during dose adjustments. Discontinue the serotonergic medications if serotonin syndrome is suspected.
Oritavancin: (Moderate) Fluoxetine is metabolized by CYP2C9, CYP2C19 and CYP2D6; oritavancin is a weak inducer of CYP2D6 and a weak CYP2C9 and CYP2C19 inhibitor. Coadministration may result in altered fluoxetine plasma concentrations. If these drugs are administered concurrently, monitor for fluoxetine toxicity, such as nausea, vomiting, diarrhea, headache, or insomnia, or decreased effectiveness.
Osilodrostat: (Moderate) Concomitant use of fluoxetine and osilodrostat may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Osimertinib: (Major) Concomitant use of osimertinib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Oxaliplatin: (Major) Concomitant use of oxaliplatin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Oxycodone: (Moderate) If concomitant use of oxycodone and fluoxetine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Oxymorphone: (Major) Fluoxetine may inhibit the metabolism of oxymorphone. Clinicians should be alert for an exaggerated opiate response if oxymorphone is given with fluoxetine.
Ozanimod: (Major) In general, do not initiate ozanimod in patients taking fluoxetine due to the risk of additive bradycardia, QT prolongation, and torsade de pointes (TdP). Additionally, there is a potential for hypertensive crisis and serotonin syndrome. If treatment initiation is considered, seek advice from a cardiologist and monitor for hypertension and serotonergic effects. Ozanimod is a monoamine oxidase inhibitor that may result in a transient decrease in heart rate and atrioventricular conduction delays. Ozanimod has not been studied in patients taking concurrent QT prolonging drugs; however, QT prolonging drugs have been associated with TdP in patients with bradycardia. Fluoxetine is a serotonergic drug that is associated with QT prolongation and TdP.
Paclitaxel: (Minor) Paciltaxel is metabolized by cytochrome P450 3A enzymes. Drugs that inhibit the CYP3A enzymes, such as fluoxetine, can significantly reduce the metabolism of paclitaxel.
Pacritinib: (Major) Concomitant use of pacritinib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Paliperidone: (Major) Concomitant use of paliperidone and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Palonosetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering palonosetron with other drugs that have serotonergic properties such as fluoxetine. If serotonin syndrome is suspected, discontinue palonosetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
Panobinostat: (Major) The co-administration of panobinostat with fluoxetine is not recommended; QT prolongation has been reported with both agents. Additionally, levels of both drugs may be increased. Although an initial panobinostat dose reduction is recommended in patients taking concomitant strong CYP3A4 inhibitors, no dose recommendations with mild or moderate CYP3A4 inhibitors are provided by the manufacturer. If concomitant use of fluoxetine and panobinostat cannot be avoided, closely monitor electrocardiograms and for signs and symptoms of fluoxetine and/or panobinostat toxicity including QT prolongation and cardiac arrhythmias. Hold panobinostat if the QTcF increases to >= 480 milliseconds during therapy; permanently discontinue if QT prolongation does not resolve. Fluoxetine is a CYP3A4 inhibitor and a CYP2D6 substrate and panobinostat is a CYP3A4 substrate and CYP2D6 inhibitor. The panobinostat Cmax and AUC (0-48hr) values were increased by 62% and 73%, respectively, in patients with advanced cancer who received a single 20 mg-dose of panobinostat after taking 14 days of a strong CYP3A4 inhibitor. When a single-dose of a CYP2D6-sensitive substrate was administered after 3 doses of panobinostat (20 mg given on days 3, 5, and 8), the CYP2D6 substrate Cmax increased by 20% to 200% and the AUC value increased by 20% to 130% in 14 patients with advanced cancer; exposure was highly variable (coefficient of variance > 150%).
Paricalcitol: (Moderate) Care should be taken when dosing paricalcitol with strong CYP3A4 inhibitors, such as fluoxetine. Dose adjustments of paricalcitol may be required. Monitor plasma PTH and serum calcium and phosphorous concentrations if a patient initiates or discontinues therapy with this combination.
Paroxetine: (Moderate) Monitor patients for an increase in adverse reactions and signs and symptoms of serotonin syndrome during concomitant use of paroxetine and fluoxetine, particularly during treatment initiation and dosage increases. If serotonin syndrome occurs, consider discontinuation of therapy. The concomitant use of serotonergic drugs increases the risk of serotonin syndrome. Concomitant use may increase paroxetine and/or fluoxetine exposure. Paroxetine is a substrate and strong inhibitor of CYP2D6 and fluoxetine is a substrate and strong inhibitor of CYP2D6.
Pasireotide: (Moderate) Concomitant use of fluoxetine and pasireotide may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Pazopanib: (Major) Concomitant use of pazopanib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Peginterferon Alfa-2b: (Moderate) Caution is warranted with the use of fluoxetine and peginterferon alfa-2b. Fluoxetine is a substrate of CYP2D6, while peginterferon alfa-2b inhibits this enzyme. The pharmacologic effects of CYP2D6 substrates may be increased when administered with peginterferon alfa-2b.
Pentamidine: (Major) Concomitant use of pentamidine and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Pentazocine: (Major) Because of the potential risk and severity of serotonin syndrome reactions, caution should be observed when administering selective serotonin reuptake inhibitors (SSRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If serotonin syndrome occurs, discontinue the offending agent(s) and institute appropriate therapy.
Pentazocine; Naloxone: (Major) Because of the potential risk and severity of serotonin syndrome reactions, caution should be observed when administering selective serotonin reuptake inhibitors (SSRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If serotonin syndrome occurs, discontinue the offending agent(s) and institute appropriate therapy.
Pentosan: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and pentosan, which has weak anticoagulant properties. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Perphenazine: (Moderate) Use fluoxetine with caution in combination with perphenazine. Coadministration may increase the risk for QT prolongation and torsade de pointes (TdP). Additionally, fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum perphenazine concentrations, leading to side effects. QT prolongation and TdP have been reported in patients treated with fluoxetine. Perphenazine is associated with a possible risk for QT prolongation.
Perphenazine; Amitriptyline: (Moderate) Monitor for signs and symptoms of serotonin syndrome, particularly during treatment initiation and dosage increase, during concomitant amitriptyline and fluoxetine use. If serotonin syndrome occurs, discontinue therapy. Concomitant use increases the risk for serotonin syndrome. (Moderate) Use fluoxetine with caution in combination with perphenazine. Coadministration may increase the risk for QT prolongation and torsade de pointes (TdP). Additionally, fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum perphenazine concentrations, leading to side effects. QT prolongation and TdP have been reported in patients treated with fluoxetine. Perphenazine is associated with a possible risk for QT prolongation.
Phenelzine: (Contraindicated) Due to the risk of serotonin syndrome, monoamine oxidase inhibitors (MAOIs) intended to treat psychiatric disorders are contraindicated for use with selective serotonin reuptake inhibitors (SSRIs). MAOIs should not be used within 5 weeks of discontinuing treatment with fluoxetine or within 14 days of discontinuing treatment with other SSRIs. Conversely, SSRIs should not be initiated within 14 days of stopping an MAOI. Monitor the patient for serotonin-related effects during therapy transitions.
Phentermine: (Moderate) Use phentermine and selective serotonin reuptake inhibitors (SSRIs) together with caution due to a potential for serotonin syndrome. Monitor weight, cardiovascular status, and for potential serotonergic adverse effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome when combined with serotonergic agents. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses and some large controlled clinical studies have allowed patients to start phentermine-based therapy for obesity along with their SSRI as long as the antidepressant dose had been stable for at least 3 months prior. Such therapy was generally well-tolerated, especially at lower phentermine doses. Because depression and obesity often coexist, the study data may be important to providing optimal co-therapies.
Phentermine; Topiramate: (Moderate) Use phentermine and selective serotonin reuptake inhibitors (SSRIs) together with caution due to a potential for serotonin syndrome. Monitor weight, cardiovascular status, and for potential serotonergic adverse effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome when combined with serotonergic agents. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses and some large controlled clinical studies have allowed patients to start phentermine-based therapy for obesity along with their SSRI as long as the antidepressant dose had been stable for at least 3 months prior. Such therapy was generally well-tolerated, especially at lower phentermine doses. Because depression and obesity often coexist, the study data may be important to providing optimal co-therapies.
Phenytoin: (Moderate) Monitor phenytoin concentrations during concomitant therapy with fluoxetine due to risk for phenytoin toxicity. Concomitant use may increase phenytoin concentrations. Phenytoin is a CYP2C9 and CYP2C19 substrate and fluoxetine is a CYP2C9 and CYP2C19 inhibitor.
Pimavanserin: (Major) Concomitant use of pimavanserin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Pimozide: (Contraindicated) Pimozide is contraindicated for use with selective serotonin reuptake inhibitors (SSRIs) due to an increased risk of QT prolongation and torsade de pointes (TdP). Pimozide is thought to be primarily metabolized through CYP3A4, and to a lesser extent, CYP1A2 and CYP2D6. Elevated plasma concentrations of pimozide occurring through inhibition of one or more of these isoenzymes by SSRIs can lead to QT prolongation, ventricular arrhythmias, and sudden death. Additionally, most SSRIs are also associated with QT prolongation, further increasing the risk of additive QT prolongation.
Pioglitazone; Metformin: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Pitolisant: (Major) Avoid coadministration of pitolisant and fluoxetine as concurrent use may increase the risk of QT prolongation. If concurrent use is unavoidable, initiate pitolisant at 8.9 mg once daily; increase pitolisant after 7 days to a maximum dosage of 17.8 mg once daily. If fluoxetine is initiated in a patient on a stable dose of pitolisant, reduce the pitolisant dose by half. Pitolisant is a CYP2D6 substrate that prolongs the QT interval; fluoxetine is a strong CYP2D6 inhibitor that has been associated with QT prolongation and torsade de pointes. Coadministration of strong CYP2D6 inhibitors increases pitolisant exposure by 2.2-fold.
Ponesimod: (Major) In general, do not initiate ponesimod in patients taking fluoxetine due to the risk of additive bradycardia, QT prolongation, and torsade de pointes (TdP). If treatment initiation is considered, seek advice from a cardiologist. Ponesimod initiation may result in a transient decrease in heart rate and atrioventricular conduction delays. Ponesimod has not been studied in patients taking concurrent QT prolonging drugs; however, QT prolonging drugs have been associated with TdP in patients with bradycardia. Fluoxetine is associated with QT prolongation and TdP.
Posaconazole: (Moderate) Concomitant use of fluoxetine and posaconazole may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Pramlintide: (Moderate) In patients with diabetes mellitus, fluoxetine may alter glycemic control. Hypoglycemia has occurred during fluoxetine therapy. Hyperglycemia has developed in patients with diabetes mellitus following discontinuation of the drug. The dosage of insulin and/or other antidiabetic agents may need to be adjusted when therapy with fluoxetine is instituted or discontinued.
Prasugrel: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving prasugrel. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SSRI concurrently with an antiplatelet medication and to promptly report any bleeding events to the practitioner.
Primaquine: (Moderate) Concomitant use of fluoxetine and primaquine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Procainamide: (Major) Concomitant use of procainamide and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Procarbazine: (Major) Procarbazine is a weak monoamine oxidase inhibitor (MAOI). Although procarbazine appears to be less likely than other MAOIs to produce serious drug interactions, clinicians should avoid the use of selective serotonin reuptake inhibitors (SSRIs) in patients receiving MAOIs. Fatalities have been reported when fluoxetine was administered to patients receiving MAOIs. Confusion, seizures, severe hypertension, and other, less severe symptoms have also been reported with this drug combination. Non-selective MAOIs inhibit both MAO types A and B. Since serotonin is metabolized by MAO type A, it is thought that this drug interaction may lead to serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. At least 2 weeks should elapse between the discontinuation of MAOI therapy and the start of therapy with an SSRI except fluoxetine. At least 5 weeks should elapse between the discontinuation of fluoxetine therapy and commencement of MAOI therapy. This 5-week period is needed because of the long half-lives of fluoxetine and its principle metabolite norfluoxetine.
Prochlorperazine: (Moderate) Use fluoxetine with caution in combination with prochlorperazine. Coadministration may increase the risk for QT prolongation and torsade de pointes (TdP). Additionally, fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum prochlorperazine concentrations, leading to side effects. QT prolongation and TdP have been reported in patients treated with fluoxetine. Prochlorperazine is associated with a possible risk for QT prolongation.
Promethazine: (Moderate) Concomitant use of promethazine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Promethazine; Dextromethorphan: (Moderate) Concomitant use of promethazine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. (Moderate) Monitor for dextromethorphan-related side effects, such as dizziness or drowsiness, if concomitant use of fluoxetine is necessary. For patients receiving combination dextromethorphan; bupropion, do not exceed a maximum dose of 45 mg dextromethorphan; 105 mg bupropion once daily. Additionally, monitor patients for signs and symptoms of serotonin syndrome. Concomitant use may increase dextromethorphan exposure and the risk for serotonin syndrome. Dextromethorphan is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant use with another strong CYP2D6 inhibitor increased dextromethorphan overall exposure by 2.69-fold.
Promethazine; Phenylephrine: (Moderate) Concomitant use of promethazine and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Propafenone: (Major) Concomitant use of fluoxetine and propafenone increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Concomitant use may also increase the exposure of propafenone, further increasing the risk of proarrhythmias. Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary. Propafenone is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant administration of propafenone and fluoxetine in extensive metabolizers increases the S-propafenone Cmax and AUC by 39% and 50%, and the R-propafenone Cmax and AUC by 71% and 50%.
Propranolol: (Moderate) Monitor for increased propranolol adverse reactions, including bradycardia and hypotension, during coadministration of fluoxetine as concurrent use may increase propranolol exposure. Propranolol is a CYP2D6 substrate and fluoxetine is a moderate CYP2D6 inhibitor.
Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for increased propranolol adverse reactions, including bradycardia and hypotension, during coadministration of fluoxetine as concurrent use may increase propranolol exposure. Propranolol is a CYP2D6 substrate and fluoxetine is a moderate CYP2D6 inhibitor. (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Protriptyline: (Moderate) Coadministration of fluoxetine and protriptyline may increase the risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. If serotonin syndrome is suspected, discontinue fluoxetine and concurrent serotonergic agents and initiate appropriate medical treatment. QT prolongation and TdP have been reported in patients treated with fluoxetine. Tricyclics, particularly at elevated concentrations, are associated with a possible risk of QT prolongation and TdP.
Quazepam: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including quazepam. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed.
Quetiapine: (Major) Avoid use together if possible. Coadministration may increase the risk for QT prolongation and torsade de pointes. Caution is also advised since both drugs act on the CNS. If use together is necessary, consider using lower initial doses of the concomitantly administered drugs, using conservative titration schedules, and monitoring of clinical status. According to the manufacturer of quetiapine, other drugs having an association with QT prolongation should not be used with quetiapine. QT prolongation and torsade de pointes (TdP) have been reported during postmarketing use of fluoxetine. The manufacturer of fluoxetine recommends caution with combined use. The effects of fluoxetine on interacting drugs may persist for several weeks after discontinuation of fluoxetine because of its long elimination half-life. In a study conducted by the manufacturer, concurrent use of 60 mg/day of fluoxetine and 300 mg twice daily of quetiapine did not alter the pharmacokinetics of quetiapine.
Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Quinidine: (Contraindicated) Concurrent use of either quinidine or dextromethorphan; quinidine and fluoxetine is considered a contraindication. Quinidine and dextromethorphan; quinidine are contraindicated for use in patients taking drugs that prolong the QT interval and are metabolized by CYP2D6. Fluoxetine is a primary substrate of CYP2D6, and is associated with a risk of QT prolongation and torsade de pointes (TdP).
Quinine: (Major) Concomitant use of quinine and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Ranolazine: (Major) Use fluoxetine with caution in combination with ranolazine. Coadministration may increase the risk for QT prolongation and torsade de pointes (TdP). Additionally, monitor for adverse effects of fluoxetine during coadministration as ranolazine may increase the concentrations of fluoxetine. QT prolongation and TdP have been reported in patients treated with fluoxetine. Ranolazine is associated with dose- and plasma concentration-related increases in the QTc interval. Fluoxetine is a substrate of CYP2D6; ranolazine is a moderate inhibitor of CYP2D6.
Rasagiline: (Major) It is recommended to avoid concurrent use of rasagiline and selective serotonin reuptake inhibitors (SSRIs). Severe CNS toxicity with hyperpyrexia has been reported during concurrent use of antidepressants and selective or non-selective MAOIs. During postmarketing use of rasagiline, non-fatal cases of serotonin syndrome have been reported during concomitant antidepressant administration. At least 2 weeks should elapse between stopping rasagiline treatment and beginning therapy with any SSRI. Conversely, when discontinuing an SSRI, it is advisable to wait the length of 4 to 5 half-lives of the individual agent being discontinued prior to initiation with rasagiline. At least 5 weeks should elapse between the discontinuation of fluoxetine therapy and initiation of rasagiline. If coadministration of rasagiline and fluvoxamine is required, do not exceed a rasagiline dose of 0.5 mg once daily. Rasagiline is primarily metabolized by CYP1A2; fluvoxamine is a strong CYP1A2 inhibitor. When rasagiline was administered with another strong CYP1A2 inhibitor, the AUC of rasagiline increased by 83%.
Relugolix: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., relugolix) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Relugolix; Estradiol; Norethindrone acetate: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., relugolix) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. (Minor) As fluoxetine inhibits CYP3A4 activity, serum estrogen concentrations and estrogenic-related side effects (e.g., nausea, breast tenderness) may potentially increase when coadministered with either estrogens or combined hormonal contraceptives.
Remifentanil: (Moderate) If concomitant use of remifentanil and selective serotonin reuptake inhibitors (SSRIs) is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Reteplase, r-PA: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving thrombolytic agents. Patients should be closely monitored for signs and symptoms of bleeding when a thrombolytic agent is administered with an SSRI.
Ribociclib: (Major) Avoid coadministration of ribociclib with fluoxetine due to an increased risk for QT prolongation and torsade de pointes (TdP). Additionally, the systemic exposure of ribociclib may be increased resulting in an increase in treatment-related adverse reactions (e.g., neutropenia, QT prolongation). Ribociclib is a CYP3A4 substrate that has been shown to prolong the QT interval in a concentration-dependent manner. Prolongation of the QT interval and TdP have been reported in patients treated with fluoxetine. While fluoxetine is a weak inhibitor of CYP3A4, its metabolite norfluoxetine is a moderate CYP3A4 inhibitor.
Ribociclib; Letrozole: (Major) Avoid coadministration of ribociclib with fluoxetine due to an increased risk for QT prolongation and torsade de pointes (TdP). Additionally, the systemic exposure of ribociclib may be increased resulting in an increase in treatment-related adverse reactions (e.g., neutropenia, QT prolongation). Ribociclib is a CYP3A4 substrate that has been shown to prolong the QT interval in a concentration-dependent manner. Prolongation of the QT interval and TdP have been reported in patients treated with fluoxetine. While fluoxetine is a weak inhibitor of CYP3A4, its metabolite norfluoxetine is a moderate CYP3A4 inhibitor.
Rilpivirine: (Moderate) Concomitant use of fluoxetine and rilpivirine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. The degree of QT prolongation associated with rilpivirine is not clinically significant when administered within the recommended dosage range; QT prolongation has been described at 3 times the maximum recommended dose.
Risperidone: (Major) Initiate risperidone at a reduced dose in patients receiving fluoxetine as increased plasma concentrations of risperidone and toxicity may occur; additive QT prolongation is also possible. Do not exceed 8 mg PO per day of risperidone if these drugs are coadministered. For the long-acting risperidone injection, the current adult dosage should be closely monitored when fluoxetine is initiated or discontinued. An adjustment of the dose may be required. Risperidone is a CYP2D6 substrate; fluoxetine is a potent CYP2D6 inhibitor. Risperidone has been associated with a possible risk for QT prolongation and/or TdP, primarily in the overdose setting. QT prolongation and TdP have also been reported in patients treated with fluoxetine.
Ritonavir: (Moderate) A dose reduction of fluoxetine may ne necessary if coadministered with ritonavir. Increased fluoxetine exposure may occur. Cardiac and neurologic events have been reported when ritonavir has been administered with fluoxetine.
Rivaroxaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and anticoagulants like rivaroxaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Rizatriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering rizatriptan with selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists ("triptans") and SSRIs. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly after the initiation of the SSRI or dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Rolapitant: (Major) Use caution if fluoxetine and rolapitant are used concurrently, and monitor for fluoxetine-related adverse effects. Fluoxetine is a CYP2D6 substrate and rolapitant is a moderate CYP2D6 inhibitor; the inhibitory effect of rolapitant is expected to persist beyond 28 days for an unknown duration. Exposure to another CYP2D6 substrate, following a single dose of rolapitant increased about 3-fold on Days 8 and Day 22. The inhibition of CYP2D6 persisted on Day 28 with a 2.3-fold increase in the CYP2D6 substrate concentrations, the last time point measured.
Romidepsin: (Moderate) Concomitant use of fluoxetine and romidepsin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Rucaparib: (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with rucaparib. Concurrent use may result in increased fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and rucaparib is a weak CYP2D6 inhibitor.
Ruxolitinib: (Moderate) Ruxolitinib is a CYP3A4 substrate. When used with drugs that are mild or moderate inhibitors of CYP3A4 such as fluoxetine, a dose adjustment is not necessary, but monitoring patients for toxicity may be prudent. There was an 8% and 27% increase in the Cmax and AUC of a single dose of ruxolitinib 10 mg, respectively, when the dose was given after a short course of erythromycin 500 mg PO twice daily for 4 days. The change in the pharmacodynamic marker pSTAT3 inhibition was consistent with the increase in exposure.
Safinamide: (Major) The concurrent use of selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs) is generally avoided; however, the manufacturer of safinamide recommends monitoring for serotonin syndrome and using the lowest effective dose of the SSRI during concurrent use. During clinical trial evaluation of safinamide, 1 case of serotonin syndrome occurred during co-administration with an SSRI. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
Salsalate: (Moderate) The combined use of selective serotonin reuptake inhibitors (SSRIs) and aspirin, ASA or other salicylates which affect hemostasis may elevate the risk for an upper GI bleed. SSRIs may inhibit serotonin uptake by platelets, augmenting the antiplatelet effects of aspirin. Additionally, aspirin impairs the gastric mucosa defenses by inhibiting prostaglandin formation. A cohort study in > 26,000 patients found that SSRI use alone increased the risk for serious GI bleed by 3.6-fold; when an SSRI was combined with aspirin the risk was increased by > 5-fold. The absolute risk of GI bleed from concomitant therapy with aspirin and a SSRI was low (20/2640 patients) in this cohort study and the clinician may determine that the combined use of these drugs is appropriate.
Saquinavir: (Major) Avoid coadministration of fluoxetine with saquinavir boosted with ritonavir due to an increased risk for QT prolongation and torsade de pointes (TdP). If no acceptable alternative therapy is available, perform a baseline ECG prior to initiation of concomitant therapy and carefully follow monitoring recommendations. QT prolongation and TdP have been reported in patients treated with fluoxetine. Saquinavir boosted with ritonavir increases the QT interval in a dose-dependent fashion, which may increase the risk for serious arrhythmias such as TdP.
Saxagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Selegiline: (Contraindicated) Selective serotonin reuptake inhibitors (SSRIs) are contraindicated for use with selegiline, a selective monoamine oxidase type B inhibitor (MAO-B inhibitor). At least 14 days should elapse between discontinuation of selegiline and initiation of treatment with an SSRI. With the exception of fluoxetine, a time period equal to 4 to 5 half-lives of the SSRI or any active metabolite should elapse after discontinuing treatment with the SSRI and before starting therapy with selegiline. Because of the long half-life of fluoxetine and its active metabolite, at least 5 weeks should elapse between discontinuation of fluoxetine and initiation of treatment with selegiline. Serotonin syndrome has occurred in patients receiving selective MAO-B inhibitors and serotonin-augmenting antidepressants simultaneously. Monitor for serotonergic side effects during therapy transitions.
Selpercatinib: (Major) Concomitant use of selpercatinib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Semaglutide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sertraline: (Major) Due to the similarity in pharmacology of fluoxetine and sertraline and the potential for serious adverse reactions, including serotonin syndrome, these selective serotonin reuptake inhibitors (SSRIs) should not be administered together. Also, both fluoxetine and sertraline have been associated with QT prolongation, which could theoretically result in additive effects on the QT interval. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SSRI to another SSRI.
Sevoflurane: (Major) Concomitant use of halogenated anesthetics and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
SGLT2 Inhibitors: (Moderate) Monitor blood glucose during concomitant SGLT2 inhibitor and fluoxetine use; a SGLT2 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sibutramine: (Major) Sibutramine is a serotonin reuptake inhibitor. Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering sibutramine with other drugs that have serotonergic properties such as selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. In addition, in vitro studies indicate that metabolism of sibutramine is mediated through CYP3A4. Theoretically, the metabolism of sibutramine may be decreased as a result of CYP3A4 inhibition by fluoxetine or fluvoxamine. Patients receiving sibutramine in combination with an SSRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
Simeprevir: (Moderate) Use caution with concurrent use of simeprevir and fluoxetine. Fluoxetine weakly inhibits CYP3A4 which may increase the plasma concentrations of simeprevir, resulting in adverse effects. The FDA-labeling recommends avoiding moderate and strong CYP3A4 inhibitors.
Simvastatin; Sitagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Siponimod: (Major) Concomitant use of siponimod and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Sirolimus: (Moderate) Agents that inhibit CYP3A4 and/or P-glycoprotein, such as fluoxetine, may affect absorption and elimination of sirolimus leading to increased blood concentrations. Monitor sirolimus serum concentrations carefully if an inhibitor of CYP3A4 or P-glycoprotein needs to be used concomitantly.
Sitagliptin: (Moderate) Monitor blood glucose during concomitant dipeptidyl peptidase-4 (DPP-4) inhibitor and fluoxetine use; a DPP-4 inhibitor dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sodium picosulfate; Magnesium oxide; Anhydrous citric acid: (Moderate) Use caution when prescribing sodium picosulfate; magnesium oxide; anhydrous citric acid in patients taking concomitant medications that are known to induce Antidiuretic Hormone Secretion (SIADH), such as tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), antipsychotics and carbamazepine, as these drugs may increase the risk of water retention and/or electrolyte imbalance.
Sodium Stibogluconate: (Moderate) Concomitant use of sodium stibogluconate and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Sofosbuvir; Velpatasvir: (Moderate) Use caution when administering velpatasvir with fluoxetine. Taking these drugs together may increase velpatasvir plasma concentrations, potentially resulting in adverse events. Fluoxetine is a weak CYP3A4 inhibitor; velpatasvir is a substrate of CYP3A4.
Sofosbuvir; Velpatasvir; Voxilaprevir: (Moderate) Use caution when administering velpatasvir with fluoxetine. Taking these drugs together may increase velpatasvir plasma concentrations, potentially resulting in adverse events. Fluoxetine is a weak CYP3A4 inhibitor; velpatasvir is a substrate of CYP3A4.
Solifenacin: (Moderate) Concomitant use of fluoxetine and solifenacin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Sorafenib: (Major) Concomitant use of sorafenib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Sotalol: (Major) Concomitant use of fluoxetine and sotalol increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Spironolactone: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
St. John's Wort, Hypericum perforatum: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering fluoxetine and St. John's Wort. Inform patients of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly during treatment initiation and dose increases. If serotonin syndrome occurs, serotonergic drugs should be discontinued and appropriate medical treatment should be initiated.
Sufentanil: (Major) Because the dose of the sufentanil sublingual tablets cannot be titrated, consider an alternate opiate if fluoxetine must be administered. Consider a reduced dose of sufentanil injection with frequent monitoring for respiratory depression, sedation, and serotonin syndrome if concurrent use of fluoxetine is necessary. If fluoxetine is discontinued, consider increasing the sufentanil injection dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system like fluoxetine has resulted in serotonin syndrome. In addition, sufentanil is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like fluoxetine can increase sufentanil exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of sufentanil. If fluoxetine is discontinued, sufentanil plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to sufentanil.
Sulfonylureas: (Moderate) Monitor blood glucose during concomitant sulfonylurea and fluoxetine use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sumatriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering sumatriptan with selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists ("triptans") and SSRIs. Inform patients of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly after initiation of SSRI treatment or any dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Sumatriptan; Naproxen: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering sumatriptan with selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists ("triptans") and SSRIs. Inform patients of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly after initiation of SSRI treatment or any dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Sunitinib: (Moderate) Concomitant use of fluoxetine and sunitinib may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Tacrolimus: (Moderate) Concomitant use of fluoxetine and tacrolimus may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Tamoxifen: (Moderate) Monitor for QT prolongation and decreased efficacy of tamoxifen if coadministration with fluoxetine is necessary. Concomitant use may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. Tamoxifen is metabolized by CYP2D6 to endoxifen and 4-hydroxytamoxifen, both of which are minor metabolites but have 100-fold greater affinity for the estrogen receptor and 30- to 100-fold greater potency in suppressing estrogen-dependent cell proliferation than tamoxifen. XXX is a strong CYP2D6 inhibitor. In one study, the mean steady-state endoxifen plasma concentration was significantly reduced in patients taking CYP2D6 inhibitors compared to those not taking concomitant CYP2D6 inhibitors. In another study, the mean steady-state plasma concentration of endoxifen in CYP2D6 normal metabolizers who were not receiving CYP2D6 inhibitors were 3.6-fold higher compared to normal metabolizers who were receiving strong CYP2D6 inhibitors; plasma concentrations in CYP2D6 normal metabolizers receiving strong CYP2D6 inhibitors were similar to concentrations observed in CYP2D6 poor metabolizers taking no CYP2D6 inhibitors. Some studies have shown that the efficacy of tamoxifen may be reduced when concomitant drugs decrease the concentrations of potent active metabolites; however, others have failed to demonstrate such an effect. The clinical significance is not well established.
Tamsulosin: (Moderate) Use caution if coadministration of fluoxetine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Tapentadol: (Moderate) If concomitant use of tapentadol and selective serotonin reuptake inhibitors (SSRIs) is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
Tedizolid: (Minor) Caution is warranted with the concurrent use of tedizolid and selective serotonin reuptake inhibitors (SSRIs) due to the theoretical risk of serotonin syndrome. Animal studies did not predict serotonergic effects; however, patients on concurrent SSRIs were excluded from clinical trials. Addtionally, tedizolid is an antibiotic that is also a weak reversible, non-selective MAO inhibitor and monoamine oxidase type A deaminates serotonin; therefore, coadministration theoretically could lead to serious reactions including serotonin syndrome. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome has been reported in patients receiving either citalopram, escitalopram, fluoxetine, or paroxetine in combination with linezolid, which is structurally similar to tedizolid.
Telavancin: (Moderate) Concomitant use of fluoxetine and telavancin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Tenecteplase: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving thrombolytic agents. Patients should be closely monitored for signs and symptoms of bleeding when a thrombolytic agent is administered with an SSRI.
Terbinafine: (Moderate) Systemic terbinafine inhibits hepatic isoenzyme CYP2D6, and thus may inhibit the clearance of drugs metabolized by this isoenzyme, such as selective serotonin reuptake inhibitors (SSRIs). The clinical relevance of the interaction is not known. Topical forms of terbinafine do not interact.
Tetrabenazine: (Major) Concomitant use of tetrabenazine and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Tezacaftor; Ivacaftor: (Minor) Although an interaction between ivacaftor and fluoxetine is possible, the clinical impact of this interaction has not yet been determined. Increased monitoring is recommended if ivacaftor is administered concurrently with CYP2C9 substrates. Fluoxetine is partially metabolized by CYP2C9, but it is also a substrate for at least 2 other enzymes. In vitro studies showed ivacaftor to be a weak inhibitor of CYP2C9. Co-administration may possibly lead to increased exposure to fluoxetine; however, because fluoxetine has multiple metabolic pathways, the clinical impact of this inhibition is not clear. In addition, ivacaftor is a CYP3A substrate, and fluoxetine is a mild CYP3A inhibitor. Co-administration may lead to increased ivacaftor exposure.
Thiazolidinediones: (Moderate) Monitor blood glucose during concomitant thiazolidinedione and fluoxetine use; a thiazolidinedione dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Thiethylperazine: (Major) Post-marketing reports suggest a possible risk of QT prolongation and TdP with fluoxetine. Thiethylperazine is associated with a possible risk of QT prolongation and TdP and caution is advisable during co-administration with fluoxetine. Fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum phenothiazine concentrations, leading to side effects. The effects of fluoxetine on hepatic metabolism of interacting drugs may persist for a time after discontinuation of fluoxetine because of its long elimination half-life.
Thioridazine: (Contraindicated) Fluoxetine is contraindicated for use with some phenothiazine antipsychotics including thioridazine. Thioridazine has an established risk of QT prolongation and torsade de pointes (TdP), and post-marketing reports suggest a possible risk of QT prolongation and TdP with fluoxetine. In addition, the metabolism of thioridazine may be decreased during use of CYP2D6 inhibitors such as fluoxetine. Due to the long half-life of fluoxetine and its active metabolite, thioridazine should not be initiated within 5 weeks after discontinuing fluoxetine. Decreased metabolism of this CYP2D6 substrates by fluoxetine may also lead to arrhythmias or other clinically important adverse reactions such as extrapyramidal symptoms.
Thrombin Inhibitors: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and other drugs that affect coagulation like thrombin inhibitors. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
Thrombolytic Agents: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving thrombolytic agents. Patients should be closely monitored for signs and symptoms of bleeding when a thrombolytic agent is administered with an SSRI.
Ticagrelor: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving ticagrelor. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SSRI concurrently with an antiplatelet medication and to promptly report any bleeding events to the practitioner.
Ticlopidine: (Moderate) Platelet aggregation may be impaired by selective serotonin reuptake inhibitors (SSRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymosis, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors (e.g., ticlopidine). Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SSRI concurrently with an antiplatelet medication and to promptly report any bleeding events to the practitioner.
Timolol: (Moderate) Monitor for signs of bradycardia or heart block if coadministration of timolol with fluoxetine is necessary. Concomitant use may enhance the beta-blocking properties of timolol resulting in further slowing of the heart rate or cardiac conduction. Timolol is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor.
Tipranavir: (Moderate) Use caution when coadministering tipranavir and ritonavir with selective serotonin reuptake inhibitors, as increased SSRI concentrations may be seen. Patients should be monitored for increased SSRI adverse effects and the SSRI dose should be adjusted if necessary.
Tirofiban: (Moderate) Platelet aggregation may be impaired by SSRIs due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving platelet inhibitors. Monitor for signs and symptoms of bleeding.
Tirzepatide: (Moderate) Monitor blood glucose during concomitant incretin mimetic and fluoxetine use; an incretin mimetic dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Tofacitinib: (Moderate) A reduction in tofacitinib dose may be necessary if tofacitinib is coadministered with fluoxetine (a strong CYP2C19 inhibitor) and a medication that is a moderate CYP3A4 inhibitor. Tofacitinib exposure is increased when coadministered with both a strong CYP2C19 and a moderate CYP3A4 inhibitor. Review the patient's other medications for this potential drug interaction and the possible need for tofacitinib dose reduction. Tofacitinib is a CYP3A4 and CYP2C19 substrate. Coadministration of tofacitinib with both a strong CYP2C19 and a moderate CYP3A4 inhibitor increased tofacitinib exposure by 1.75-fold.
Tolterodine: (Moderate) Coadministration of fluoxetine and tolterodine may increase the risk for QT prolongation and torsade de pointes (TdP). QT prolongation and TdP have been reported in patients treated with fluoxetine. Tolterodine has been associated with dose-dependent prolongation of the QT interval, especially in poor CYP2D6 metabolizers.
Toremifene: (Major) Concomitant use of toremifene and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Torsemide: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Tramadol: (Moderate) Monitor for reduced efficacy of tramadol, signs of opioid withdrawal, seizures, or serotonin syndrome if coadministration with fluoxetine is necessary. If fluoxetine is discontinued, consider a dose reduction of tramadol and frequently monitor for signs of respiratory depression and sedation. Tramadol is a CYP2D6 substrate and fluoxetine is a CYP2D6 inhibitor. Concomitant use of tramadol with CYP2D6 inhibitors can increase the plasma concentration of tramadol and decrease the plasma concentration of the active metabolite M1. Since M1 is a more potent mu-opioid agonist, decreased M1 exposure could result in decreased therapeutic effects, and may result in signs and symptoms of opioid withdrawal in patients who have developed physical dependence to tramadol. Increased tramadol exposure can result in increased or prolonged therapeutic effects and increased risk for serious adverse events including seizures and serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Tramadol; Acetaminophen: (Moderate) Monitor for reduced efficacy of tramadol, signs of opioid withdrawal, seizures, or serotonin syndrome if coadministration with fluoxetine is necessary. If fluoxetine is discontinued, consider a dose reduction of tramadol and frequently monitor for signs of respiratory depression and sedation. Tramadol is a CYP2D6 substrate and fluoxetine is a CYP2D6 inhibitor. Concomitant use of tramadol with CYP2D6 inhibitors can increase the plasma concentration of tramadol and decrease the plasma concentration of the active metabolite M1. Since M1 is a more potent mu-opioid agonist, decreased M1 exposure could result in decreased therapeutic effects, and may result in signs and symptoms of opioid withdrawal in patients who have developed physical dependence to tramadol. Increased tramadol exposure can result in increased or prolonged therapeutic effects and increased risk for serious adverse events including seizures and serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
Tranylcypromine: (Contraindicated) Due to the risk of serotonin syndrome, monoamine oxidase inhibitors (MAOIs) intended to treat psychiatric disorders are contraindicated for use with selective serotonin reuptake inhibitors (SSRIs). MAOIs should not be used within 5 weeks of discontinuing treatment with fluoxetine or within 14 days of discontinuing treatment with other SSRIs. Conversely, SSRIs should not be initiated within 14 days of stopping an MAOI. Monitor the patient for serotonin-related effects during therapy transitions.
Trazodone: (Major) Trazodone and fluoxetine may both cause QT prolongation. Concurrent use may also increase the risk of serotonin syndrome. Serotonin syndrome has been reported with both drugs when taken alone, but especially when coadministered with other serotonergic agents. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate appropriate treatment if serotonin syndrome occurs.
Triamterene: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Triazolam: (Moderate) Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including triazolam. Patients should be monitored for clinical response, and adjust benzodiazepine dosage if needed.
Triclabendazole: (Moderate) Concomitant use of triclabendazole and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Trifluoperazine: (Moderate) Coadministration of fluoxetine and trifluoperazine may increase the risk for QT prolongation and torsade de pointes (TdP). Additonally, fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum trifluoperazine concentrations, leading to side effects. QT prolongation and TdP have been reported in patients treated with fluoxetine. Trifluoperazine is associated with a possible risk for QT prolongation.
Trimipramine: (Moderate) Coadministration of fluoxetine and trimipramine may increase the risk for QT prolongation, torsade de pointes (TdP), and serotonin syndrome. If serotonin syndrome is suspected, discontinue fluoxetine and concurrent serotonergic agents and initiate appropriate medical treatment. QT prolongation and TdP have been reported in patients treated with fluoxetine. Tricyclics, particularly at elevated concentrations, are associated with a possible risk of QT prolongation and TdP.
Triptorelin: (Moderate) Concomitant use of fluoxetine and androgen deprivation therapy (i.e., triptorelin) may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Tryptophan, 5-Hydroxytryptophan: (Major) Concurrent use of tryptophan and a selective serotonin reuptake inhibitor (SSRI) is not recommended. Since tryptophan is converted to serotonin, the use of tryptophan in patients receiving SSRIs could lead to serotonin excess and, potentially, serotonin syndrome. Discontinuation of tryptophan usually resolves symptoms.
Ubrogepant: (Major) Limit the initial and second dose of ubrogepant to 50 mg if coadministered with fluoxetine. Concurrent use may increase ubrogepant exposure and the risk of adverse effects. Ubrogepant is a CYP3A4 substrate; fluoxetine is a weak CYP3A4 inhibitor.
Valbenazine: (Major) Consider reducing the dose of valbenazine, based on tolerability, during co-administration with a strong CYP2D6 inhibitor, such as fluoxetine. QT prolongation is not clinically significant at valbenazine concentrations expected with recommended dosing; however, concentrations of the active metabolite of valbenazine may be higher in patients taking a strong CYP2D6 inhibitor and QT prolongation may become clinically significant. Additionally, cases of QT prolongation and ventricular arrhythmias, including torsade de pointes (TdP), have been reported during post-marketing use of fluoxetine.
Valerian, Valeriana officinalis: (Moderate) Substances that act on the CNS, including psychoactive drugs, may theoretically interact with valerian, Valeriana officinalis. These interactions are probably pharmacodynamic in nature, or result from additive mechanisms of action. Persons taking medications such as SSRIs should discuss the use of herbal supplements with their health care professional prior to consuming these herbs. Patients should not abruptly stop taking their prescribed psychoactive medication.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and fluoxetine use; consider discontinuing fluoxetine if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing hyponatremia.
Vandetanib: (Major) Concomitant use of vandetanib and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Vardenafil: (Moderate) Concomitant use of vardenafil and fluoxetine may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Vasopressin, ADH: (Moderate) Monitor hemodynamics and adjust the dose of vasopressin as needed when used concomitantly with drugs suspected of causing syndrome of inappropriate antidiuretic hormone (SIADH), such as selective serotonin reuptake inhibitors. Use together may increase the pressor and antidiuretic effects of vasopressin.
Vemurafenib: (Major) Vemurafenib has been associated with QT prolongation. If vemurafenib and another drug that is associated with a possible risk for QT prolongation and torsade de pointes (TdP) must be coadministered, ECG monitoring is recommended; closely monitor the patient for QT interval prolongation. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. In addition, concomitant use of vemurafenib and fluoxetine may result in increased concentrations of fluoxetine and vemurafenib. Vemurafenib is a substrate of CYP3A4 and an inhibitor of CYP2C9 and CYP2D6. Fluoxetine is an inhibitor of CYP3A4 and a substrate of CYP2C9 and CYP2D6. Use caution and monitor patients for toxicity and efficacy.
Venetoclax: (Major) Reduce the dose of venetoclax by at least 50% and monitor for venetoclax toxicity (e.g., hematologic toxicity, GI toxicity, and tumor lysis syndrome) if coadministered with fluoxetine due to the potential for increased venetoclax exposure. Resume the original venetoclax dose 2 to 3 days after discontinuation of fluoxetine. Venetoclax is a CYP3A4 substrate; norfluoxetine, the active metabolite of fluoxetine, is a moderate CYP3A4 inhibitor.
Venlafaxine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like venlafaxine. If serotonin syndrome is suspected, all serotonergic agents should be discontinued. Also, both fluoxetine and venlafaxine have been associated with QT prolongation and torsade de pointes (TdP), which could theoretically result in additive effects on the QT interval.
Vilazodone: (Major) Due to possible additive effects on serotonin concentrations, it is advisable to avoid combining selective serotonin reuptake inhibitors (SSRIs) with vilazodone. Interactions between vilazodone and serotonergic agents can lead to serious reactions including serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored closely for toxicity.
Viloxazine: (Moderate) Monitor for increased fluoxetine-related adverse effects if coadministered with viloxazine. Concomitant use may increase fluoxetine exposure. Fluoxetine is a CYP2D6 substrate and viloxazine is a weak CYP2D6 inhibitor.
Vinblastine: (Moderate) Monitor for an earlier onset and/or increased severity of vinblastine-related adverse reactions, including myelosuppression, constipation, and peripheral neuropathy, if coadministration with fluoxetine is necessary. Vinblastine is a CYP3A4 substrate and norfluoxetine, the active metabolite of fluoxetine, is a moderate CYP3A4 inhibitor. Enhanced vinblastine toxicity was reported with coadministration of another moderate CYP3A4 inhibitor.
Vinorelbine: (Moderate) Monitor for an earlier onset and/or increased severity of vinorelbine-related adverse reactions, including constipation and peripheral neuropathy, if coadministration with fluoxetine is necessary. Vinorelbine is a CYP3A4 substrate. Fluoxetine is a weak CYP3A4 inhibitor, but its active metabolite, norfluoxetine, is a moderate inhibitor of CYP3A4.
Voclosporin: (Moderate) Concomitant use of fluoxetine and voclosporin may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP. The degree of QT prolongation associated with voclosporin is not clinically significant when administered within the recommended dosage range; QT prolongation has been described at 3 times the maximum recommended dose.
Vonoprazan; Amoxicillin; Clarithromycin: (Major) Concomitant use of clarithromycin and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Vorapaxar: (Moderate) Because vorapaxar inhibits platelet aggregation, a potential additive risk for bleeding exists if vorapaxar is given in combination with other agents that affect hemostasis such as selective serotonin reuptake inhibitors (SSRIs). Platelet aggregation may be impaired by SSRIs due to platelet serotonin depletion. In addition, fluoxetine and fluvoxamine are CYP3A4 inhibitors and coadministration with vorapaxar, a CYP3A4 substrate, may result in increased serum concentrations of vorapaxar. Increased exposure to vorapaxar may increase the risk of bleeding complications. Patients should be instructed to monitor for signs and symptoms of bleeding while taking a SSRI with vorapaxar and to promptly report any bleeding events.
Voriconazole: (Moderate) Concomitant use of fluoxetine and voriconazole may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Vorinostat: (Moderate) Concomitant use of fluoxetine and vorinostat may increase the risk of QT/QTc prolongation and torsade de pointes (TdP) in some patients. Consider taking steps to minimize the risk of QT/QTc interval prolongation and TdP, such as avoidance, electrolyte monitoring and repletion, and ECG monitoring, especially in patients with additional risk factors for TdP.
Vortioxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, vortioxetine should generally not be co-administered with selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Monitor for serotonin syndrome during the transition from vortioxetine to an SSRI. If co-administration is necessary, the manufacturer recommends a reduction in the vortioxetine dose by one-half during when strong inhibitors of CYP2D6 such as fluoxetine are used since CYP2D6 is the primary isoenzyme responsible for the metabolism of vortioxetine to its inactive metabolite. The vortioxetine dose should be increased to the original level when the CYP2D6 inhibitor is discontinued.
Warfarin: (Moderate) Closely monitor the INR if coadministration of warfarin with fluoxetine is necessary as concurrent use may increase the exposure of warfarin leading to increased bleeding risk. Fluoxetine is a weak CYP3A4 inhibitor and the R-enantiomer of warfarin is a CYP3A4 substrate. Fluoxetine is also a weak CYP2C9 inhibitor and the S-enantiomer, the active metabolite of warfarin, is a CYP2C9 substrate. An increased risk of bleeding, including gastrointestinal bleeding, has been reported with drugs that interfere with serotonin reuptake; thus, concurrent use of fluoxetine and warfarin may result in an additive risk of bleeding events. The S-enantiomer of warfarin exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer, but the R-enantiomer generally has a slower clearance.
Ziprasidone: (Major) Concomitant use of ziprasidone and fluoxetine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Zolmitriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering zolmitriptan with selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists ("triptans") and SSRIs. Inform patients of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly after initiation of SSRI treatment or any dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.

PREGNANCY AND LACTATION

Available data from published epidemiologic studies and postmarketing reports have not established an increased risk of major birth defects or miscarriage from the use of fluoxetine during pregnancy. There are risks to the mother associated with untreated depression (e.g., relapse) and a potential risk of persistent pulmonary hypertension of the newborn (PPHN). Several publications reported an increased incidence of cardiovascular malformations in children with in utero exposure to fluoxetine. However, a causal relationship has not been established due to methodologic limitations of the studies, including possible exposure and outcome misclassification, lack of adequate controls, adjustment for confounders and confirmatory studies. Some neonates exposed to SSRIs late in the third trimester have experienced poor neonatal adaptation resulting in complications requiring prolonged hospitalization, respiratory support, and tube feeding upon delivery. Symptoms have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor, jitteriness, irritability, and constant crying. These features are consistent with direct SSRI toxicity, serotonin syndrome, or a drug discontinuation syndrome. The effect of SSRIs on labor and delivery in humans is unknown. There is a pregnancy exposure registry that monitors outcomes in pregnant patients exposed to fluoxetine; information about the registry can be obtained at https://womensmentalhealth.org/research/pregnancyregistry/antidepressants or by calling 1-866-961-2388. 

MECHANISM OF ACTION

The precise antidepressant effect of SSRIs is not fully understood, but involves selective serotonin reuptake blockade at the neuronal membrane, which enhances the actions of serotonin (5-HT). Initially, SSRIs increase availability of serotonin in the somatodendritic area through serotonin reuptake blockade at the serotonin transport pump. During long-term administration of SSRIs, serotonin autoreceptors are down-regulated and desensitized, allowing the neuron to increase serotonin release in the axon terminal synapses and increase its neuronal impulses. Because of the delay in therapeutic response to SSRIs, it is theorized that the change in the balance of serotonin receptors over time is an important mechanism of effect. The therapeutic action of SSRIs in treating anxiety disorders is thought to occur from potent central serotonin reuptake blockade although the exact mechanism is unknown. SSRIs have less sedative, anticholinergic, and cardiovascular effects than do tricyclic antidepressants due to dramatically decreased binding to histaminergic, muscarinic, and alpha-adrenergic receptors. Norfluoxetine, the active metabolite of fluoxetine, is a potent and selective reuptake inhibitor of serotonin with activity which is essentially bioequivalent to the parent compound.

PHARMACOKINETICS

Fluoxetine is administered orally. Steady-state plasma concentrations of fluoxetine and its principal active metabolite S-norfluoxetine are achieved after 3 to 4 weeks of daily dosing in both adult and pediatric patients. Both fluoxetine and norfluoxetine exist as enantiomers. In-vitro, each enantiomer, except R-norfluoxetine appears to have equivalent potency in the inhibition of serotonin reuptake. However, these four compounds differ in kinetics and no relationship between serum concentrations and clinical effect has been defined. Fluoxetine is highly protein-bound (94.5%) predominantly to alpha-1 acid glycoprotein. The drug is well distributed. Fluoxetine is demethylated in the liver to several metabolites. It is primarily a substrate for CYP2D6; however, both CYP2D6 and CYP2C9 contribute to the formation of R-norfluoxetine, whereas only CYP2D6 is responsible for conversion to S-norfluoxetine. Fluoxetine has the slowest elimination of the SSRIs. The elimination half-life after chronic administration is 4 to 6 days; however, there is considerable individual variation, which may be associated with variance in the rates of N-demethylation and hydroxylation. In one pharmacokinetic evaluation, the mean terminal half-life of norfluoxetine after a single dose was 8.6 days and after multiple dosing was 9.3 days. The primary route of elimination appears to be metabolism in the liver to metabolites that are subsequently excreted by the kidneys.
 
Affected cytochrome P450 (CYP450) isoenzymes and drug transporters: CYP2D6, CYP2C19, CYP3A4, CYP2C9
Fluoxetine is a primary substrate of CYP2D6. Fluoxetine is