Fluoxetine
Pronunciation: floo-OX-e-teen.
Last medically reviewed: August 14, 2026, by Dr. Rina Basnet, MBBS, MD (Internal Medicine).
- Generic name
- fluoxetine
- Drug class
- Selective serotonin reuptake inhibitor (SSRI) antidepressant
- Form
- Capsule, tablet, dispersible tablet, delayed-release weekly capsule, and oral solution (strengths vary by country and product, typically 10 mg, 20 mg, 40 mg, 60 mg, and a 90 mg weekly formulation)
- Route
- Oral
- Legal status
- Prescription-only in all markets reviewed
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand
Australia: Prozac; generic fluoxetine (e.g. Fluoxetine Generic Health, Fluoxetine Pharmacor) (5) · Full directory
Boxed warning: Increased risk of suicidal thinking and behaviour in children, adolescents, and young adults
Fluoxetine carries a boxed warning (the US FDA's strongest safety warning): antidepressants increased the risk, compared with placebo, of suicidal thinking and behaviour (suicidality) in children, adolescents, and young adults in short-term studies of Major Depressive Disorder and other psychiatric disorders. Anyone considering fluoxetine, or any antidepressant, for a child, adolescent, or young adult must weigh this risk against the clinical need for treatment. Short-term studies did NOT show an increased risk of suicidality with antidepressants compared with placebo in adults beyond age 24, and there was a REDUCED risk with antidepressants compared with placebo in adults aged 65 and older. All patients starting fluoxetine, at any age, should be monitored closely for worsening symptoms and for the emergence of suicidal thoughts and behaviours, especially during the first few weeks of treatment or after a dose change. Families and caregivers should be told about this need for close observation and should be given clear instructions to contact the prescriber immediately if these signs appear. Fluoxetine is not approved for use in children under 7 years of age. (1)
What fluoxetine is and how it works
Fluoxetine is a prescription antidepressant belonging to the SSRI (selective serotonin reuptake inhibitor) class. It works by increasing the amount of serotonin, a chemical messenger in the brain linked to mood, available between nerve cells. It is one of the most widely prescribed antidepressants worldwide and has been in use for decades. (1)
Fluoxetine carries a genuine safety warning: in short-term studies, antidepressants as a class -- including fluoxetine -- were linked to an increased risk of suicidal thinking and behaviour in children, adolescents, and young adults under 25. This risk was not seen in older adults, and risk was actually lower with antidepressant treatment in adults 65 and older. Anyone starting fluoxetine, at any age, should be watched closely for worsening mood or new suicidal thoughts, especially in the first few weeks or after a dose change, and should know to contact their prescriber immediately if these appear.
Mechanism of action: how fluoxetine works
Fluoxetine is a selective serotonin reuptake inhibitor (SSRI). It blocks the reuptake transporter for serotonin at the presynaptic neuron, increasing the amount of serotonin available in the synapse, which is thought to underlie its antidepressant, anti-obsessional, and anti-bulimic effects. It is metabolised in the liver (partly via CYP2D6) to norfluoxetine, an active metabolite with an even longer half-life, which is why fluoxetine and its effects persist in the body for weeks after the last dose. (1) (2)
What fluoxetine is used for
Major depressive disorder (depression)
Used to treat major depressive disorder in adults, and (in the US and UK sources reviewed) in children and adolescents aged 7/8 and older for moderate-to-severe depression that has not responded to psychological therapy. Health Canada's product monograph states fluoxetine is not indicated for patients under 18, and the New Zealand data sheet advises against paediatric use -- always follow local prescribing guidance for a child or adolescent. (1) (2) (4) (6)
Obsessive-compulsive disorder (OCD)
Used to treat OCD in adults, and (in the US source reviewed) in children and adolescents aged 7-17. This indication is also recognised in the UK, Canadian, Australian, and New Zealand sources reviewed for adults. (1) (2) (4) (6)
Bulimia nervosa
Used in adults, alongside psychotherapy, to help reduce binge-eating and purging behaviour. This is the indication with the clearest single effective dose across markets (60 mg/day). (1) (2) (4) (6)
Panic disorder
Used in adults for panic disorder, with or without agoraphobia (fear of situations that might trigger panic) -- confirmed as an indication in the US source reviewed. (1)
Premenstrual dysphoric disorder (PMDD)
Used continuously throughout the menstrual cycle for PMDD, a severe form of premenstrual syndrome with pronounced mood and physical symptoms tied to the menstrual cycle -- confirmed as an approved indication in the Australian and New Zealand sources reviewed. This indication was not found in the specific US DailyMed label or UK SmPC reviewed for this dossier. (5) (6)
Before taking fluoxetine
Do not take / not appropriate for
- Do not take fluoxetine if you are taking, or have taken within the last 14 days, a monoamine oxidase inhibitor (MAOI), including the antibiotic linezolid or the dye methylene blue -- combining these can cause a serious, potentially fatal reaction. (all countries) (1) (4)
- Do not take fluoxetine if you have a known serious allergic reaction to fluoxetine or its ingredients. (all countries) (2) (4)
- Do not take fluoxetine together with pimozide or thioridazine, due to a risk of dangerous heart-rhythm changes (QT prolongation). (United States, Canada) (1) (4)
- Do not take fluoxetine together with metoprolol used specifically for heart failure -- confirmed as a contraindication in the UK source reviewed. (United Kingdom) (2)
Tell your clinician about
- Any history of suicidal thoughts, self-harm, or a family history of bipolar disorder or mania.
- Any heart rhythm problems, or a family history of QT-interval problems.
- Any history of low blood sodium (hyponatraemia), especially if you are elderly or take diuretics.
- Any history of bleeding problems, or if you take anticoagulants, aspirin, or NSAIDs.
- Any liver problems -- fluoxetine and its active metabolite last longer in the body if the liver is affected.
- All other medicines, especially MAOIs, other antidepressants or serotonergic medicines, tricyclic antidepressants, antipsychotics, lithium, tamoxifen, or St John's Wort.
- Whether you are pregnant, plan to become pregnant, or are breastfeeding.
How to take fluoxetine
- Usually taken once daily in the morning, with or without food.
- Fluoxetine and its main active breakdown product stay in the body for a long time (several weeks), which is different from most other antidepressants -- this affects how interactions and switching between medicines are managed by your prescriber.
- It can take several weeks of treatment before the full effect on mood or symptoms is felt -- do not expect an immediate result.
- Any change in dose, or a decision to stop fluoxetine, should always be made together with your prescriber, not on your own.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)
Missed dose
If you miss a dose, take it as soon as you remember on the same day, unless it is close to the time of your next dose -- if so, contact your prescriber or pharmacist for guidance rather than taking a double dose. Because fluoxetine stays in the body for a long time, a single missed dose is less likely to cause a sudden change, but ask your prescriber if you are unsure.
Overdose
Seek urgent medical attention if you think you or someone else has taken too much fluoxetine, or if you notice symptoms such as seizures, severe drowsiness, an irregular or fast heartbeat, agitation, confusion, or signs of serotonin syndrome (see Serious Warnings). Take the medicine packaging with you if possible. (1)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms.
Headache.
What to notice: Headache.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)
Nausea and other gastrointestinal upset.
What to notice: Nausea and other gastrointestinal upset.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)
Insomnia and other sleep disturbances, including vivid dreams.
What to notice: Insomnia and other sleep disturbances, including vivid dreams.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)
Fatigue, tremor, dizziness, and sensory disturbances such as tingling.
What to notice: Fatigue, tremor, dizziness, and sensory disturbances such as tingling.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)
Diarrhoea.
What to notice: Diarrhoea.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)
Sexual dysfunction, which can sometimes persist after stopping treatment.
What to notice: Sexual dysfunction, which can sometimes persist after stopping treatment.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)
Reduced appetite and weight loss.
What to notice: Reduced appetite and weight loss.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)
Agitation, anxiety, or restlessness (akathisia).
What to notice: Agitation, anxiety, or restlessness (akathisia).
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)
Serious warnings
Worsening depression or emergence of suicidal thoughts (especially in children, adolescents, and young adults under 25) — boxed_warning
Symptoms: New or worsening depression, anxiety, agitation, panic attacks, irritability, hostility, aggression, impulsivity, restlessness, unusual changes in behaviour, or thoughts of suicide or self-harm -- particularly in the first few weeks of treatment or after a dose change.
Action: Contact your prescriber immediately, or seek emergency help if there is any immediate danger. Families and caregivers should watch closely for these signs, especially early in treatment, and report them to the prescriber right away. (1) (4)
Signs of serotonin syndrome — emergency
Symptoms: Agitation, hallucinations, fast heartbeat, high body temperature, muscle rigidity or twitching, loss of coordination, sweating, shivering, nausea, vomiting, or diarrhoea -- especially if combined with another serotonergic medicine or an MAOI.
Action: Seek emergency medical help immediately. This is a rare but potentially life-threatening reaction, and your prescriber will manage any concurrent serotonergic medicines with this risk in mind. (1) (2)
Signs of an abnormal heart rhythm (QT prolongation) — high caution
Symptoms: Fainting, palpitations, dizziness, or a noticeably irregular heartbeat.
Action: Seek prompt medical attention. This risk is why fluoxetine must not be combined with pimozide or thioridazine, and why caution is needed with other medicines that affect heart rhythm. (1) (2)
Signs of low blood sodium (hyponatraemia) — high caution
Symptoms: Headache, confusion, weakness, unsteadiness, or in severe cases seizures -- more common in elderly patients and those on diuretics.
Action: Contact your prescriber promptly for assessment, especially if you are elderly or taking a diuretic. (2)
Unusual bleeding or bruising — high caution
Symptoms: Nosebleeds, easy bruising, blood in vomit or stool, or unusually heavy menstrual bleeding -- risk is higher when combined with NSAIDs, aspirin, or anticoagulants.
Action: Contact your prescriber for assessment, particularly if you also take a blood-thinning or anti-inflammatory medicine. (2)
Signs of mania or hypomania — high caution
Symptoms: Unusually elevated mood, racing thoughts, decreased need for sleep, or impulsive behaviour -- reported more often in children and adolescents.
Action: Contact your prescriber for assessment before continuing treatment as before. (1) (2)
Interactions
- Monoamine oxidase inhibitors (MAOIs), including the antibiotic linezolid and the dye methylene blue: must not be combined with fluoxetine, due to risk of a serious, potentially fatal reaction (serotonin syndrome/NMS-like features). A washout period is required in both directions -- at least 14 days after stopping an MAOI before starting fluoxetine, and at least 5 weeks (perhaps longer) after stopping fluoxetine before starting an MAOI, because of fluoxetine's long half-life. (1) (4)
- Other serotonergic medicines (triptans, tramadol, lithium, St John's Wort, tryptophan): increase the risk of serotonin syndrome; combining fluoxetine with tryptophan specifically is not recommended. (1)
- Pimozide and thioridazine: contraindicated due to risk of dangerous heart-rhythm changes (QT prolongation); fluoxetine can also raise thioridazine blood levels via CYP2D6 inhibition. (1) (4)
- Metoprolol used for heart failure: contraindicated, per the UK source reviewed. (2)
- Tricyclic antidepressants (e.g. imipramine, desipramine), haloperidol, clozapine, risperidone, flecainide, and propafenone: fluoxetine inhibits the CYP2D6 enzyme and can substantially raise blood levels of these medicines, sometimes requiring a dose adjustment by the prescriber and closer monitoring. (1) (2)
- Tamoxifen: combining with fluoxetine is not recommended, since fluoxetine reduces levels of tamoxifen's active form (endoxifen) via the same CYP2D6 pathway. (2)
- Anticoagulants, aspirin, and NSAIDs: combined use with fluoxetine is associated with a higher risk of bleeding, particularly gastrointestinal bleeding. (1) (2)
- Lithium: blood levels have been reported both increased and decreased with concurrent fluoxetine, including cases of lithium toxicity -- monitoring is needed. (1)
- Benzodiazepines (e.g. diazepam, alprazolam): fluoxetine may prolong diazepam's effects and increase alprazolam levels and psychomotor impairment. (1)
- Phenytoin and carbamazepine: blood levels may increase with concurrent fluoxetine, raising toxicity risk. (1)
- Electroconvulsive therapy (ECT): rare reports of prolonged seizures in patients taking fluoxetine who receive ECT. (1)
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Fluoxetine is used in pregnancy only when the clinical need justifies the risk, decided together with your prescriber. Exposure late in the third trimester has been linked to neonatal complications requiring extended hospital care (respiratory distress, feeding difficulty, temperature instability, tremor, seizures), and SSRI exposure after the 20th week of pregnancy has been linked to a higher risk of persistent pulmonary hypertension of the newborn (PPHN) in some studies. Possible increased risk of cardiovascular birth defects has also been described in the UK source reviewed. Your prescriber may consider adjusting treatment in the third trimester. (1) (2) (3) (4) (5) (6)
Breastfeeding
Fluoxetine passes into breast milk. Continuing to breastfeed, switching to a different antidepressant, or using the lowest effective dose are all decisions to make together with your prescriber, weighing the benefits of breastfeeding and treatment against the possibility of neonatal effects. (1) (2) (3) (4) (5) (6)
Children
Approved for major depressive disorder (US: age 8+; UK: age 8+, only for moderate-to-severe depression unresponsive to psychotherapy) and OCD (US: age 7+) in some markets. Health Canada's product monograph states fluoxetine is not indicated below age 18, and the New Zealand data sheet advises against paediatric use despite trials having been conducted. Growth effects (reduced height/weight gain) and a higher rate of manic reactions have been reported in paediatric patients in the US source reviewed -- always follow local specialist guidance for a child or adolescent. (1) (2) (3) (4) (5) (6)
Elderly
A lower or less frequent dose should be considered by the prescriber. Elderly patients have a higher risk of low blood sodium (hyponatraemia) with SSRIs. The US source reviewed noted a reduced (not increased) suicidality risk with antidepressant treatment in adults 65 and older, compared with placebo. (1) (2) (3) (4) (5) (6)
Hepatic_impairment
Fluoxetine and its active metabolite last longer in the body (half-life of about 7-12 days reported) if the liver is affected; the prescriber may consider a lower dose or alternate-day dosing. (1) (2) (3) (4) (5) (6)
Renal_impairment
A single dose has minimal effect on kinetics in the sources reviewed; the prescriber may still monitor for drug accumulation with long-term use. (1) (2) (3) (4) (5) (6)
Source_ids
US-DAILYMED-FLUOXETINE-2026,UK-EMC-FLUOXETINE-2026,CA-HC-FLUOXETINE-PM-2026,NZ-MEDSAFE-FLUOX-2026 (1) (2) (3) (4) (5) (6)
Monitoring
Before starting
- Assessment for personal or family history of bipolar disorder, mania, or suicidal thoughts
- Review of all other medicines for MAOI or serotonergic interactions
- Baseline blood sodium level if at higher risk (e.g. elderly, on diuretics)
- Baseline weight/growth tracking in children and adolescents where prescribed
During treatment
- Close monitoring for worsening mood or emergence of suicidal thoughts, especially in the first few weeks of treatment or after a dose change, and especially in patients under 25.
- Monitoring for signs of serotonin syndrome if other serotonergic medicines are used concurrently.
- Periodic reassessment of ongoing benefit, particularly for long-term use and for PMDD (reassessed after six months in the sources that describe this indication).
- Growth and development monitoring in children and adolescents, where prescribed.
Storage
Store at room temperature, away from moisture and direct light, out of reach of children.
Study the drug class: SSRI antidepressants
Professional information
Clinician-facing context only, sourced from the current US FDA prescribing information, UK emc SmPC, and Health Canada product monograph reviewed for this dossier; verify against the current full label before prescribing.
United States
Indication: MDD, OCD, bulimia nervosa, panic disorder
Dose summary: MDD: 20 mg/day initial, max 80 mg/day (adults); paediatric 8-18 initial 10-20 mg/day. OCD: 20 mg/day initial, range 20-60 mg/day (adults); paediatric 7-17 with weight-based dosing. Bulimia: 60 mg/day. Panic disorder: 10 mg/day initial, increase to 20 mg/day after 1 week, max 60 mg/day.
Renal context: Minimal single-dose kinetic effect described; monitor accumulation with long-term use. (1)
United Kingdom
Indication: MDD, OCD, bulimia nervosa
Dose summary: MDD: 20 mg/day initial, max 60 mg/day. OCD: 20 mg/day initial, up to 60 mg/day if inadequate response after 2 weeks. Bulimia: 60 mg/day. Paediatric (8+, MDD only): 10 mg/day initial (oral solution), increase to 20 mg after 1-2 weeks. Elderly: generally not exceeding 40 mg/day, max 60 mg.
Renal context: Not specifically dose-adjusted per the source reviewed. (2)
Canada
Indication: MDD, bulimia nervosa, OCD (adults only -- not indicated under 18)
Dose summary: MDD: 20 mg/day initial, max 60 mg/day. Bulimia: 60 mg/day recommended (electrolytes assessed first). Switching to/from MAOI: 14 days after stopping MAOI before starting fluoxetine; 5+ weeks after stopping fluoxetine before starting MAOI.
Renal context: Not specifically detailed in the source reviewed. (4)
Australia / New Zealand
Indication: MDD, OCD, bulimia nervosa, PMDD (New Zealand data sheet also covers panic-adjacent anxiety with depression)
Dose summary: Depression: 20 mg/day. Bulimia: 60 mg/day. OCD: 20-60 mg/day. PMDD: 20 mg/day continuously, reassessed after 6 months. Paediatric use not recommended per the New Zealand source reviewed.
Renal context: Not specifically detailed in the sources reviewed. (6) (5)
Hepatic guidance
Half-life is prolonged in hepatic impairment (7-12 days reported); the prescriber may consider a lower dose or alternate-day dosing.
Overdose note
Manage with supportive care and close monitoring for seizures, cardiac arrhythmia, and serotonin syndrome; no specific antidote. (1) (2)
Frequently asked questions
Is fluoxetine available in the US, UK, Europe, Canada, Australia, and New Zealand?
Yes. Fluoxetine is authorised and marketed in all six regions -- as Prozac and many generic names in the US, UK, Canada, Australia, and New Zealand (also as Arrow-Fluoxetine and FLUOX in New Zealand), and nationally across European Union member states (for example, as Adofen in Spain, alongside numerous generics). (1) (2) (3) (4) (5) (6)
Why does fluoxetine have a boxed warning about suicidal thoughts?
Because in short-term clinical trials, antidepressants as a class -- including fluoxetine -- were linked to a higher rate of suicidal thinking and behaviour in children, adolescents, and young adults under 25, compared with placebo. This risk was not seen in older adults, and was actually lower with antidepressant treatment in adults 65 and older. Anyone starting fluoxetine at any age should be watched closely for worsening mood or new suicidal thoughts, especially early in treatment, and should contact their prescriber immediately if these appear. (1)
Can I take fluoxetine if I'm also taking another antidepressant or an MAOI?
Fluoxetine must never be combined with a monoamine oxidase inhibitor (MAOI), and a washout period is required in both directions (at least 14 days after stopping an MAOI before starting fluoxetine, and at least 5 weeks after stopping fluoxetine before starting an MAOI) because of the serious, potentially fatal risk of serotonin syndrome. Combining fluoxetine with other serotonergic medicines also needs your prescriber's assessment. Never start, stop, or combine antidepressants without medical guidance. (1) (4)
Is fluoxetine approved for premenstrual dysphoric disorder (PMDD) everywhere?
No -- this is a real difference between the markets reviewed. PMDD is an approved indication in the Australian and New Zealand sources reviewed (20 mg/day, continuously through the cycle), but was not found in the specific US or UK labels reviewed for this dossier. Ask your prescriber whether this indication applies in your country. (5) (6)
What is the mechanism of action of fluoxetine?
Fluoxetine is a selective serotonin reuptake inhibitor (SSRI). It blocks the reuptake transporter for serotonin at the presynaptic neuron, increasing the amount of serotonin available in the synapse, which is thought to underlie its antidepressant, anti-obsessional, and anti-bulimic effects. It is metabolised in the liver (partly via CYP2D6) to norfluoxetine, an active metabolite with an even longer half-life, which is why fluoxetine and its effects persist in the body for weeks after the last dose. (1) (2)
References
- FLUOXETINE (fluoxetine hydrochloride) capsule -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · dated 2026-01-01 · accessed 2026-07-30 · source 1
- Fluoxetine 20 mg Capsules -- Summary of Product Characteristics (SmPC)electronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics, Flamingo Pharma (UK) Ltd · United Kingdom · dated 2025-09-06 · accessed 2026-07-30 · source 2
- Fluoxetine: list of nationally authorised medicinal products (PSUSA/00001442/202209)European Medicines Agency (EMA) -- list of nationally authorised medicinal products (periodic safety update single assessment) · European Union · dated 2022-09-01 · accessed 2026-07-30 · source 3
- FLUOXETINE (fluoxetine hydrochloride capsules, USP) -- Product MonographHealth Canada -- Product Monograph (Sivem Pharmaceuticals ULC, generic fluoxetine) · Canada · dated 2018-06-11 · accessed 2026-07-30 · source 4
- PROZAC 20 (fluoxetine 20 mg as hydrochloride) capsule, blister pack -- ARTG entry 14653; PBS item 1434LTherapeutic Goods Administration (TGA), Australia -- Australian Register of Therapeutic Goods (ARTG) and PBS · Australia · dated 2026-07-01 · accessed 2026-07-30 · source 5
- FLUOX (fluoxetine hydrochloride) capsules and dispersible tablets -- New Zealand Data SheetMedsafe (New Zealand Medicines and Medical Devices Safety Authority) -- New Zealand Data Sheet · New Zealand · dated 2026-01-01 · accessed 2026-07-30 · source 6
Brand names by country
Single-ingredient fluoxetine names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Prozac40 mg, 10 mg, 20 mg · dista products company
United Kingdom
- Fluoxetine (generic; multiple manufacturers, e.g. Flamingo Pharma) (2)emc current smpc confirmed · 20 mg capsules, 60 mg capsules, 20 mg/5 mL oral solution · Flamingo Pharma (UK) Ltd and other generic manufacturers listed on emc
Canada
- PROZAC
- ACH-FLUOXETINE
Australia
- Prozac; generic fluoxetine (e.g. Fluoxetine Generic Health, Fluoxetine Pharmacor) (5)tga artg registered confirmed · 10 mg, 20 mg capsules · Eli Lilly Australia Pty Ltd (Prozac); generic manufacturers
New Zealand
- Prozac; Arrow-Fluoxetine; FLUOX (6)medsafe data sheet confirmed · 20 mg capsules, 20 mg dispersible tablets · Multiple Medsafe-approved suppliers (brand and generic)
View brands in additional countries.
European Union
Adofen (and numerous national generics) (3)