fluoxetine

Adjunctive therapy

Brands: PROZAC

Last reviewed 2026-02-01

Reviewed by PsychMed Editorial Team.

View details

Quick answers

What is fluoxetine?
Fluoxetine (Prozac) is a long half-life SSRI used for depression, OCD, bulimia nervosa, and bipolar depression (in combination with olanzapine).
What is PROZAC?
PROZAC is a brand name for fluoxetine.
What is PROZAC (fluoxetine) used for?
Label indications include: Major depressive disorder; OCD; panic disorder; use with olanzapine for bipolar depression.
What drug class is PROZAC (fluoxetine)?
Selective serotonin reuptake inhibitor (SSRI).
What strengths does PROZAC (fluoxetine) come in?
Capsules 10–40 mg, tablets 10–60 mg, delayed-release capsule 90 mg weekly, oral solution 20 mg/5 mL.

Snapshot

Class: Adjunctive therapy
Common US brands: PROZAC
Therapeutic drug monitoring not routinely recommended.
Last reviewed: 2026-02-01

Label indications

Major depressive disorder; OCD; panic disorder; use with olanzapine for bipolar depression.

View labelExact

Clinical Highlights

Fluoxetine (Prozac) is a long half-life SSRI used for depression, OCD, bulimia nervosa, and bipolar depression (in combination with olanzapine). Its activating profile and low discontinuation risk make it useful in adherence-challenged patients.

The long half-life (including norfluoxetine) makes dose changes slower and drug interactions more durable; washouts and switches often require more lead time than other SSRIs to reduce adverse interactions.
Symptom improvement is typically gradual: early side effects (GI upset, sleep changes, jitteriness) may occur in the first days, while mood and anxiety benefits often take several weeks.
Because fluoxetine strongly inhibits CYP2D6, dose effects on co-prescribed antipsychotics or TCAs can persist for weeks; medication reconciliation is especially important during switches and cross-tapers.
The compare view and fluoxetine evidence feed can help contrast activation, discontinuation, and interaction trade-offs when revising long-term regimens.
Mania/hypomania monitoring can be coordinated via the bipolar disorder hub, and the fluoxetine print page can support counseling and shared decision-making.
Potent CYP2D6 inhibition can require dose adjustments for many psychotropics (e.g., risperidone, aripiprazole, TCAs).
Major depressive disorder (FDA 1987)
Obsessive-compulsive disorder (FDA 1994)
Bulimia nervosa (FDA 1994)

Dosing & Formulations

Capsules 10–40 mg, tablets 10–60 mg, delayed-release capsule 90 mg weekly, oral solution 20 mg/5 mL. Typical adult start is 20 mg once daily (often morning); may increase to 40–60 mg/day after several weeks if needed and tolerated.

Lower initial doses (10 mg) are often used in anxiety disorders.
A 5-week washout is required before starting an MAOI due to long half-life.

Monitoring & Risks

Boxed warning: Antidepressants increase suicidality risk in young adults; closer monitoring is common. Insomnia/activation: Morning dosing is often considered.

Nausea: Often improves after several days.
Diarrhea: Dietary adjustments can help.
Sexual dysfunction: Management strategies can be discussed.
Serotonin syndrome risk increases when combined with other serotonergic agents; concomitant medications are typically reviewed carefully.
Hyponatremia (SIADH) risk; sodium monitoring is common in older adults and other higher-risk patients.
Additive bleeding risk with NSAIDs, antiplatelets, and anticoagulants; counseling often covers bruising and GI bleeding symptoms.

Drug Interactions

Potent CYP2D6 inhibitor—adjust coadministered CYP2D6 substrates (TCAs, antipsychotics, beta-blockers) as needed, with clinical monitoring. Contraindicated with MAOIs; a 5-week washout after stopping fluoxetine is required before initiating an MAOI.

Reduces tamoxifen efficacy due to CYP2D6 inhibition.

Practice Notes

Long half-life reduces discontinuation risk but prolongs adverse effects after stopping. Metabolic parameters are commonly assessed when combined with olanzapine (Symbyax).

Mania/hypomania surveillance can be supported via the bipolar disorder hub, and dosing/interaction tips can be shared via the fluoxetine print page.
When switching from fluoxetine to another antidepressant, account for its prolonged washout (especially before MAOI therapy) to reduce toxicity risk.
If daily adherence is difficult, a once-weekly delayed-release capsule may be an option after stabilization; confirm appropriateness against labeling and comorbid hepatic disease when stable.

References

PROZAC (fluoxetine) prescribing information — DailyMed (2024)
Symbyax Label 2025
APA Clinical Practice Guideline for the Treatment of Depression — American Psychiatric Association (2023)Guidelinedepressionclinical
CANMAT 2024 Clinical Guidelines for Major Depressive Disorder — Canadian Journal of Psychiatry (2024)
Comparative efficacy and acceptability of 21 antidepressant drugs for major depressive disorder — The Lancet (2018)Meta-analysisdepressionefficacy