fluoxetine (Rx)

Brand and Other Names:Prozac, Sarafem, more...Prozac Weekly, Selfemra
  • Print

Dosing & Uses


Dosage Forms & Strengths


  • 10mg
  • 20mg
  • 40mg


  • 10mg
  • 20mg
  • 60mg

capsule, delayed-release

  • 90mg

oral solution

  • 20mg/5mL

Major Depressive Disorder


  • Initial: 20 mg PO qDay
  • May consider gradually increasing dose after several weeks by 20 mg/day; not to exceed 80 mg qDay

Prozac Weekly

  • 90 mg PO qWeek

Obsessive-Compulsive Disorder


  • Initial: 20 mg PO qDay
  • May consider gradually increasing dose after several weeks by 20 mg/day (20-60 mg/day recommended range); not to exceed 80 mg qDay

Prozac Weekly

  • 90 mg PO qWeek

Bulimia Nervosa

Initial or maintenance: May titrate dose to 60 mg PO qDay over several days

Panic Disorder

Initial: 10 mg PO qDay for first week, THEN 20 mg PO qDay

May consider gradually increasing dose after several weeks; not to exceed 60 mg qDay; doses > 60 mg/day not evaluated

Premenstrual Dysphoric Disorder

Continuous (Sarafem): 20 mg PO qDay initially; may gradually increase dose; not to exceed 80 mg/day, OR

Intermittent (Sarafem): 20 mg PO qDay starting 14 days before menstruation and through first full day of menses (repeat each cycle)

Fibromyalgia (Off-label)

20-80 mg PO qDay

Dosing considerations

  • Efficacy may increase with concomitant amitriptyline

Migraine (Off-label)


20-40 mg PO qDay

Hot Flashes Caused by Hormonal Chemotherapy (Off-label)

20 mg/day PO x 4 weeks

Raynaud Phenomenon (Off-label)

20-60 mg/day PO

Dosing Modifications

Upon therapy discontinuation, taper gradually over 4-6 months to minimize incidence of withdrawal symptoms and allow for detection of re-emerging symptoms; if withdrawal symptoms intolerable, following a dose reduction, resume previously prescribed dose and/or decrease dose at more gradual rate

Renal impairment: Use caution; drug accumulation may occur with severe renal impairment

Hepatic impairment (cirrhosis): Decreased clearance of parent drug and active metabolite (norfluoxetine); lower or less frequent dose recommended

Dosage Forms & Strengths


  • 10mg
  • 20mg
  • 40mg


  • 10mg
  • 20mg
  • 60mg

oral solution

  • 20mg/5mL

Major Depressive Disorder

>8 years: 10-20 mg PO qDay, initially

Start at 10 mg/day in lower weight children

May gradually increase dose after 1 week; not to exceed 20 mg qDay

Obsessive-Compulsive Disorder

>7 years: 10 mg PO qDay, initially; may gradually increase dose after 2 weeks to 20 mg qDay; further increases may be considered after several weeks

Adolescents and higher-weight children: Typical dosage range 20-60 mg qDay

Lower-weight children: Typical dosage range 20-30 mg qDay

Body Dysmorphic Disorder (Orphan)

Treatment of body dysmorphic disorder in children and adolescents

Orphan indication sponsor

  • Hollander, Eric MD; The Mount Sinai School of Medicine, One Gustave L. Levy Place; New York, NY 10029-6574

Autism (Orphan)

Orphan indication sponsor

  • Neuropharm, Ltd; Felcham Park House, Lower Road, Leatherhead; UK

Major Depressive Disorder

Initial: 10 mg PO qDay

May gradually increase dose by 10-20 mg after several weeks as tolerated

Do not take at night unless sedation occurs

Dosing Considerations

Preferred drug of choice in elderly over tricyclic antidepressants because of fewer side effects



Interaction Checker

and fluoxetine

No Results

     activity indicator 
    No Interactions Found
    Interactions Found


      Serious - Use Alternative

        Significant - Monitor Closely


            All Interactions Sort By:
             activity indicator 

            Adverse Effects


            Headache (20-25%)

            Nausea (12-29%)

            Insomnia (10-33%)

            Anorexia (4-17%)

            Anxiety (6-15%)

            Asthenia (10-15%)

            Diarrhea (8-18%)

            Nervousness (8-14%)

            Somnolence (5-17%)

            Tremor (3-13%)

            Weakness (7-21%)


            Dizziness (9%)

            Dry mouth (6-10%)

            Dyspepsia (6-10%)

            Sweating (5-10%)

            Decreased libido (2-5%)

            Abnormal taste (>1%)

            Agitation (>1%)

            Chest pain (>1%)

            Chills (>1%)

            Confusion (>1%)

            Ear pain (>1%)

            Hypertension (>1%)

            Increased appetite (>1%)

            Palpitation (>1%)

            Sleep disorder (>1%)

            Tinnitus (>1%)

            Urinary frequency (>1%)

            Vomiting (>1%)

            Weight gain (>1%)

            Frequency Not Defined

            Dysglycemia in patients with DM

            Risk of seizure with concomitant electroconvulsive therapy (rare)

            Poarmarketing Reports




            Black Box Warnings

            In short-term studies, antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults (<24 years) taking antidepressants for major depressive disorders and other psychiatric illnesses

            This increase was not seen in patients >24 years; a slight decrease in suicidal thinking was seen in adults >65 years

            In children and young adults, the risks must be weighed against the benefits of taking antidepressants

            Patients should be monitored closely for changes in behavior, clinical worsening, and suicidal tendencies; this should be done during the initial 1-2 months of therapy and dosage adjustments

            The patient’s family should communicate any abrupt changes in behavior to the health-care provider

            Worsening behavior and suicidal tendencies that are not part of the presenting symptoms may require discontinuation of therapy

            Not FDA approved for treatment of bipolar depression or children < 7 years



            Concomitant pimozide or thioridazine (within 5 weeks of administering fluoxetine)


            Coadministration with MAOIs

            • Coadministration may cause serotonin syndrome
            • Coadministration of MAOIs with fluoxetine or within 5 weeks of discontinuing fluoxetine
            • Initiating fluoxetine within 14 days of administering an MAOI
            • Starting fluoxetine in a patient who is being treated with linezolid or IV methylene blue is contraindicated because of an increased risk of serotonin syndrome
            • If linezolid or IV methylene blue must be administered, discontinue fluoxetine immediately and monitor for CNS toxicity; may resume fluoxetine 24 hr after last linezolid or methylene blue dose or after 5 weeks of monitoring, whichever comes first


            Clinical worsening and suicidal ideation may occur despite medication in adolescents and young adults (aged 18-24 years)

            Development of potentially life-threatening serotonin syndrome reported with SNRIs and SSRIs alone but particularly with concomitant use of other serotonergic drugs (including triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines, and St. Johns Wort) if concomitant use with these types of drugs is clinically warranted, inform patients of potential increased risk for serotonin syndrome, particularly during treatment initiation and dose increases (see Contraindications and Drug Interactions)

            Risk of bleeding (GI and other) when used in combination with NSAIDs, aspirin, or drugs affecting coagulation; may impair platelet aggregation

            Activation of mania/hypomania (screen for bipolar disorder)

            Fluoxetine therapy has been associated with occurrence of rash and allergic reaction, including vasclitis; discontinue if they occur

            Bone fractures have been associated with antidepressant therapy; consider possibility of bone fracture when patient presents with bone pain

            May cause or exacerbate sexual dysfunction

            Use caution in patients with risk for QT prolongation, including congenital long QT syndrome, history of prolonged QT, or history of prolonged QT; QT prolongation and ventricular arrhythmia, iincluding torsade de pointes

            Hyponatremia reported with use; consider discontinuation if symptomatic hyponatremia occurs

            Use caution in patients with history of seizure disorders

            May prolong QT interval and cause ventricular arrhythmia, including torsade de pointes

            May cause nervousness, anxiety, insomnia, or anorexia

            Risk of mydriasis; may trigger angle closure attack in patients with angle closure glaucoma with anatomically narrow angles without a patent iridectomy

            Hypoglycemia reported; may alter glycemic control in patients with diabetes

            Conflicting evidence reported regarding use of SSRIs during pregnancy and increased risk of persistent pulmonary hypertension of the newborn, or PPHN (see Pregnancy)

            Risk of complications in neonates exposed to SNRIs/SSRIs late in third trimester (eg, feeding difficulties, irritability, and respiratory problems)

            Wait 1 week after discontinuation of Prozac before starting Prozac Weekly

            Gradually decrease dose when discontinuing

            Has long half-life, decrease in dose will not be fully reflected in plasma for several weeks

            Conditions that predispose to QT prolongation and ventricular arrhythmia; such conditions include concomitant use of drugs that prolong the QT interval; hypokalemia or hypomagnesemia; recent myocardial infarction, uncompensated heart failure, bradyarrhythmias, and other significant arrhythmias

            Consider ECG assessment and periodic ECG monitoring if initiating treatment with fluoxetine in patients with risk factors for QT prolongation and ventricular arrhythmia; consider discontinuing fluoxetine and obtaining a cardiac evaluation if patients develop signs or symptoms consistent with ventricular arrhythmia


            Pregnancy & Lactation


            Pregnancy category: C

            Treatment of pregnant women during the first trimester: There are no adequate and well-controlled clinical studies on the use of fluoxetine in pregnant women, but 1 prospective cohort study conducted by the European Network of Teratology Information Services reported an increased risk of cardiovascular malformations in infants born to women (N = 253) exposed to fluoxetine during the first trimester of pregnancy, compared with infants of women (N = 1359) who were not exposed to fluoxetine

            Use late in the third trimester associated with complications in newborns and may require prolonged hospitalization, respiratory support, and tube feeding

            When treating a pregnant woman with fluoxetine, physician should carefully consider trimester both for the potential risks of taking an SSRI, along with the established benefits of treating depression with an antidepressant; the decision can only be made on a case by case basis

            A study of nearly 28,000 women taking SSRIs confirmed 2 previously reported birth defercts associated with fluoxetine - heart wall defects and craniosynostosis (BMJ 2015; 351:h3190)

            Persistent pulmonary hypertension of the newborn

            • Potential risk of PPHN when used during pregnancy
            • Initial public health advisory, in 2006, was based on a single published study; since then, there have been conflicting findings from new studies, making it unclear whether the use of SSRIs during pregnancy can cause PPHN
            • The FDA has reviewed the new study results and has concluded that, given the conflicting results from different studies, it is premature to reach any conclusion about a possible link between SSRI use in pregnancy and PPHN
            • FDA recommendation: The FDA advises health-care professionals not to alter their current clinical practice of treating depression during pregnancy and to report any adverse events to the FDA MedWatch program
            • A meta-analysis of 7 observational studies, found exposure to SSRIs in late pregnancy (ie, >20 weeks' gestation) more than doubled the risk of PPHN that could not be explained by other etiologies (eg, congenital malformations, meconium aspiration) (BMJ 2014;348:f6932)


            Excreted in milk; avoid (AAP states effect on nursing infants is unknown but may be of concern)

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.



            Mechanism of Action

            Selective serotonin reuptake inhibitor; little or no affinity for alpha-adrenergic histamine or cholinergic receptor


            Peak plasma time: 6-8 hr

            Peak plasma concentration: 15-55 ng/mL

            Steady-state plasma concentration: 91-302 ng/mL (parent drug), 72-258 ng/mL (metabolite)

            Time to peak: 6-8 hr (serum)


            Protein bound: 95%

            Vd: 12-43 L/kg


            Hepatic P450 enzyme CYP2D6 substrate

            Enzymes induced: CYP2C9

            Enzymes inhibited: CYP2C19, CYP2D6, CYP3A4

            Metabolites: Norfluoxetine


            Half-life: 4-6 days (chronic administration); 1-3 days (acute); 7-6 days (cirrhosis)

            Dialyzable: No

            Excretion: Urine (15%)


            Several SSRIs (eg, fluoxetine, fluvoxamine, paroxetine, sertraline) are metabolized by CYP2D6

            CYP2D6 is involved in the metabolism of approximately 20% of drugs in clinical use and displays large individual-to-individual variability in activity due to genetic polymorphisms

            More than 80 CYP2D6 variant alleles have been identified; however, 4 of the most prevalent alleles, CYP2D6*3, *4, *5, and *6, account for 93-97% of CYP2D6 poor metabolizers (PMs)

            CYP2D6*4, the most common variant (~25% frequency in whites), causes a splicing defect, CYP2D6*3 (2.7% frequency) causes a frameshift mutation, and CYP3D6*5 (2.6%) is an entire deletion of the CYP2D6 gene; individuals homozygous for these alleles have no CYP2D6 activity

            The impact of CYP2D6 activity is further complicated by some SSRIs (eg, fluoxetine, fluvoxamine, paroxetine, sertraline) that, in addition to being substrates for CYP2D6, are also known to moderately inhibit CYP2D6 activity

            Genetic testing laboratories

            • Genotyping tests for CYP2D6 variants are commercially available through the following companies
            • Applied Biosystems (http://www.appliedbiosystems.com/)
            • GenPath Diagnostics (http://www.genpathdiagnostics.com/)




            FormularyPatient Discounts

            Adding plans allows you to compare formulary status to other drugs in the same class.

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

            Adding plans allows you to:

            • View the formulary and any restrictions for each plan.
            • Manage and view all your plans together – even plans in different states.
            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
            Additional Offers
            Email to Patient



            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            Email Forms to Patient



            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.