Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) widely prescribed for the management of major depressive disorder, obsessive-compulsive disorder, panic disorder, and bulimia nervosa. As one of the most extensively studied antidepressants, it offers a favorable balance of efficacy and tolerability. Its mechanism of action involves increasing serotonin levels in the brain, which helps regulate mood, emotion, and behavior. Clinical evidence supports its use in both acute treatment and long-term maintenance therapy.

Features

• Selective serotonin reuptake inhibitor (SSRI) class
• Available in 10 mg, 20 mg, and 40 mg oral capsules
• Also offered as liquid solution (20 mg/5 mL) and delayed-release capsules
• FDA-approved for multiple psychiatric and eating disorders
• Generic versions available, enhancing accessibility
• Once-daily dosing convenience for most indications

Benefits

• Significantly reduces symptoms of depression and anxiety disorders
• Helps restore emotional balance and improves overall quality of life
• Reduces frequency and intensity of panic attacks and obsessive thoughts
• Effective in managing binge-eating and purging behaviors in bulimia nervosa
• Lower risk of cardiovascular effects compared to older antidepressants
• Suitable for long-term maintenance therapy with established safety profile

Common use

Fluoxetine is primarily indicated for the treatment of major depressive disorder (MDD) in adults and pediatric patients aged 8 years and older. It is also approved for obsessive-compulsive disorder (OCD), panic disorder with or without agoraphobia, and bulimia nervosa. Off-label uses include treatment of premenstrual dysphoric disorder (PMDD), post-traumatic stress disorder (PTSD), and certain anxiety spectrum disorders. Healthcare providers may also prescribe it as part of combination therapy for treatment-resistant depression.

Dosage and direction

For major depressive disorder in adults, the initial recommended dose is 20 mg once daily in the morning. Dosage may be increased after several weeks if insufficient clinical improvement is observed, with maximum recommended dose of 80 mg daily. For OCD, initial adult dosing is 20 mg daily, with possible titration up to 80 mg daily. Panic disorder typically begins with 10 mg daily, increasing to 20 mg daily after one week. Bulimia nervosa treatment involves 60 mg daily, which may be administered either in morning or divided doses. Pediatric dosing for MDD (ages 8-18) starts at 10-20 mg daily. Always take with food or water to minimize gastrointestinal discomfort. Do not crush or chew capsules; swallow whole.

Precautions

Patients should be monitored closely for clinical worsening, suicide risk, or unusual changes in behavior, particularly during initial months of therapy or dosage adjustments. Use with caution in patients with history of mania/hypomania. May impair judgment, thinking, or motor skills; caution when operating machinery. Regular monitoring of weight is recommended as significant changes may occur. Elderly patients may require dosage adjustments due to reduced clearance. Abrupt discontinuation may lead to withdrawal symptoms; taper gradually under medical supervision. Not recommended during third trimester of pregnancy due to potential neonatal complications.

Contraindications

Absolute contraindications include known hypersensitivity to fluoxetine or any component of the formulation. Concomitant use with monoamine oxidase inhibitors (MAOIs) is contraindicated due to risk of serotonin syndrome; allow minimum 14-day washout period between therapies. Contraindicated in patients taking pimozide or thioridazine due to potential for serious cardiac arrhythmias. Not recommended in patients with uncontrolled narrow-angle glaucoma. Use with extreme caution in patients with severe hepatic impairment.

Possible side effect

Common adverse reactions (≥5% incidence) include headache, nausea, insomnia, fatigue, drowsiness, anxiety, nervousness, dizziness, and diarrhea. Sexual dysfunction including decreased libido, delayed ejaculation, and anorgasmia may occur. Less frequent side effects include dry mouth, sweating, rash, itching, decreased appetite, and weight changes. Serious but rare adverse effects include serotonin syndrome, abnormal bleeding, hyponatremia, seizures, angle-closure glaucoma, and manic episodes. Report any unusual bruising, bleeding, or visual changes immediately.

Drug interaction

Fluoxetine is a strong inhibitor of CYP2D6 and moderate inhibitor of CYP3A4, potentially increasing levels of numerous medications. Significant interactions occur with: other serotonergic drugs (increased serotonin syndrome risk), MAOIs, tryptophan, anticoagulants (increased bleeding risk), antiplatelets, NSAIDs, other antidepressants, antipsychotics, certain antiarrhythmics, benzodiazepines, beta-blockers, and anticonvulsants. Use with caution with drugs that prolong QT interval. May alter blood levels of tricyclic antidepressants, lithium, and some migraine medications. Inform your physician of all medications, including over-the-counter drugs and supplements.

Missed dose

If a dose is missed, take it as soon as remembered unless it is close to the time for the next scheduled dose. In that case, skip the missed dose and resume regular dosing schedule. Do not double the dose to make up for a missed one. Consistent daily administration at approximately the same time is recommended for maintained therapeutic effect. If multiple doses are missed, contact your healthcare provider for guidance.

Overdose

Symptoms of overdose may include nausea, vomiting, agitation, restlessness, hypomania, seizures, and drowsiness. Serious cases may involve serotonin syndrome, characterized by confusion, hallucinations, extreme changes in blood pressure, increased heart rate, fever, excessive sweating, shivering or shaking, blurred vision, muscle spasm or stiffness, tremor, incoordination, stomach cramp, nausea, vomiting, and diarrhea. No specific antidote exists; provide supportive care and symptomatic treatment. Gastric lavage with activated charcoal may be considered if presented early. Contact poison control center (1-800-222-1222) or emergency services immediately.

Storage

Store at controlled room temperature (20°-25°C or 68°-77°F) with excursions permitted between 15°-30°C (59°-86°F). Keep container tightly closed and protect from moisture and light. Keep out of reach of children and pets. Do not use after expiration date printed on packaging. Properly dispose of any unused medication through medication take-back programs or according to FDA guidelines. Do not flush medications down the toilet unless specifically instructed to do so.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Individual response to medication may vary. Always consult with a qualified healthcare professional before starting, changing, or discontinuing any medication. The prescribing physician should determine appropriate treatment based on individual patient characteristics and medical history. Only healthcare providers can assess benefits versus risks for specific patients.

Reviews

Clinical studies demonstrate fluoxetine’s efficacy with response rates of 50-70% in major depressive disorder. Meta-analyses confirm superiority over placebo with number needed to treat (NNT) of 6-8 for depression. Long-term studies show maintained efficacy for up to 12 months with acceptable tolerability. Patient-reported outcomes indicate significant improvements in quality of life measures and functional capacity. Many clinicians note its particularly favorable profile in patients with comorbid anxiety symptoms. The side effect profile is generally considered more favorable than older antidepressants, though individual tolerance varies.