At a glance

Active ingredient: fluoxetine (an SSRI antidepressant; brands may include Prozac and Sarafem in the USA).

Typical strengths available:

  • 10 mg capsules or tablets
  • 20 mg capsules or tablets

Main therapeutic areas: mental health and some women's health conditions related to mood symptoms.

Quick jump: Uses | How to take | Side effects | Interactions | Alternatives | Prices | Law in the USA

What fluoxetine treats

Fluoxetine helps restore balance of serotonin in the brain by selectively blocking its reuptake in neurons. This mechanism can improve mood, reduce anxiety and panic, and ease obsessive or compulsive behaviors.

  • Bulimia nervosa
  • Premenstrual dysphoric disorder (PMDD)
  • Panic disorder
  • Obsessive-compulsive disorder (OCD)
  • Major depressive disorder (MDD)

Note: For PMDD, fluoxetine is often marketed as Sarafem; for bulimia nervosa, higher doses than those used for depression are commonly prescribed.

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How to take fluoxetine

Always use exactly as your prescriber directs. If you have a delayed-release or enteric-coated capsule, swallow it whole without crushing, chewing, or opening.

Do not stop suddenly unless your clinician provides a taper plan. Abrupt changes may trigger withdrawal-like symptoms or return of your original condition.

Because fluoxetine has a long half-life, dose changes may take several weeks to show their full effect.

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Safety checks before and during treatment

Tell your clinician about all medical conditions and every medicine or supplement you take. Extra caution is needed if you have a history of:

  • Bipolar disorder or manic episodes
  • Seizures or epilepsy
  • Sexual dysfunction concerns
  • Narrow-angle glaucoma
  • Diabetes
  • Liver problems such as cirrhosis
  • Urination difficulties
  • Substance use disorder or past suicidal thoughts
  • Recent or planned electroconvulsive therapy (ECT)

Pregnancy and lactation: late-pregnancy SSRI exposure can be associated with complications in newborns. If breastfeeding, contact your clinician if the infant shows unusual fussiness, feeding problems, or poor weight gain.

Alcohol may intensify certain side effects; discuss safe use with your clinician.

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Do not use if

  • You have taken an MAOI in the last 14 days or plan to take one within 5 weeks after stopping fluoxetine.
  • You are allergic to fluoxetine or any of its components.
  • You are taking pimozide or thioridazine.

Timing rules to prevent dangerous interactions:

  • Wait at least 14 days after stopping an MAOI before starting fluoxetine.
  • Wait at least 5 weeks after stopping fluoxetine before starting an MAOI or thioridazine.

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Possible side effects

Get emergency help right away if you suspect a severe allergic reaction (rash with blistering, swelling of face or throat, trouble breathing) or a severe skin reaction.

Seek urgent care if you notice symptoms of serotonin syndrome such as agitation, fever, sweating, shivering, rapid heart rate, muscle rigidity or twitching, loss of coordination, nausea, vomiting, or diarrhea.

Serious effects that require prompt medical advice:

  • Very stiff muscles, high fever, confusion, fast or irregular pulse, or fainting feelings
  • Severely low sodium: confusion, severe weakness, vomiting, slurred speech, loss of coordination
  • Eye pain or swelling, seeing halos, tunnel vision, or sudden vision changes
  • Rapid or pounding heartbeat, chest fluttering, shortness of breath, sudden dizziness

Common effects that are usually mild and may improve with time:

  • GI upset: nausea, vomiting, diarrhea, reduced appetite
  • Headache, dizziness, drowsiness, or changes in vision
  • Insomnia or vivid dreams
  • Dry mouth, sweating, or hot flashes
  • Tremor or feeling jittery
  • Fatigue, yawning, or general weakness
  • Cold symptoms: stuffy nose, sore throat, sinus discomfort
  • Weight or appetite changes
  • Lowered libido, difficulty with orgasm, or erectile dysfunction

Report any new or worsening mood or behavior changes, including increased anxiety, restlessness, irritability, agitation, impulsivity, trouble sleeping, or thoughts of self-harm.

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Drug and supplement interactions

Many medicines can interact with fluoxetine, including those that affect heart rhythm or serotonin, or that increase bleeding risk.

  • Serotonergic agents: other antidepressants, triptans for migraine, tramadol, St. John's wort, tryptophan
  • Medications that prolong QT interval: certain antiarrhythmics, antipsychotics, macrolide antibiotics, and others
  • NSAIDs or blood thinners: ibuprofen, naproxen, aspirin, warfarin and similar agents may raise bleeding risk
  • Stimulants for ADHD or narcolepsy: amphetamine products, methylphenidate, lisdexamfetamine
  • Mood disorder agents: lithium, amitriptyline, desipramine, nortriptyline, buspirone
  • Opioids and sedatives: fentanyl, tramadol, benzodiazepines, sleeping pills, muscle relaxants can increase drowsiness

Important cautions:

  • Do not combine with MAOIs or thioridazine/pimozide.
  • Ask your clinician before adding any new prescription, OTC medicine, or supplement.

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Missed dose

Take it when remembered unless it is close to your next scheduled time. If so, skip the missed dose and resume your normal schedule. Do not double up.

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Overdose

Seek emergency medical attention. In the USA, you can also contact Poison Help at 1-800-222-1222.

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Storage

  • Store at room temperature, protected from moisture and excess heat.
  • Keep out of reach of children and pets.

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Similar or alternative medications

Depending on your diagnosis, history, side effect profile, and cost considerations, clinicians may consider one of the following instead of, or after trying, fluoxetine:

  • SSRIs: sertraline (Zoloft), escitalopram (Lexapro), citalopram (Celexa), paroxetine (Paxil), fluvoxamine
  • SNRIs: venlafaxine (Effexor XR), desvenlafaxine (Pristiq), duloxetine (Cymbalta)
  • Atypical antidepressants: bupropion (Wellbutrin), mirtazapine (Remeron), vilazodone (Viibryd), vortioxetine (Trintellix)
  • For PMDD: sertraline or drospirenone-ethinyl estradiol oral contraceptives may be considered
  • For OCD: sertraline, fluvoxamine, clomipramine
  • For bulimia nervosa: fluoxetine has the most evidence and an FDA indication; psychotherapy is essential

Choice among alternatives is individualized. For example, bupropion is often activating and weight-neutral but is not typically used for anxiety disorders; sertraline is commonly favored for PMDD and panic disorder; duloxetine may be preferred if coexisting pain syndromes are present.

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Prices in the USA - rough comparisons

Prices vary by pharmacy, insurance, dosage, and formulation. The estimates below reflect typical cash prices or discount program prices for a 30-day supply:

  • Fluoxetine generic 20 mg daily: about USD 4 to 15 at large retail pharmacies or with common discount cards
  • Fluoxetine generic 10 mg daily: about USD 4 to 15
  • Brand Prozac (if available): often USD 150 to 400+ depending on dose and pharmacy
  • Sarafem for PMDD: brand prices commonly USD 150 to 350+
  • Alternative SSRI generics (sertraline, citalopram, escitalopram, paroxetine): usually USD 4 to 20 per month
  • SNRIs (venlafaxine, duloxetine) generics: generally USD 10 to 40 per month
  • Atypicals: bupropion and mirtazapine generics often USD 8 to 30; vilazodone or vortioxetine brands can exceed USD 350 to 550+ monthly

If you have insurance, your copay may be much lower. Many pharmacies honor $4 generic lists for common doses.

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