Fluoxetine is a widely prescribed selective serotonin reuptake inhibitor (SSRI) indicated for the treatment of major depressive disorder, obsessive-compulsive disorder, panic disorder, and bulimia nervosa. As a first-line pharmacological intervention, it functions by increasing serotonin levels in the brain, which helps improve mood, sleep, appetite, and energy levels. Its established efficacy, favorable safety profile, and once-daily dosing make it a cornerstone in psychiatric and primary care practice for managing these conditions.

Features

• Selective serotonin reuptake inhibitor (SSRI)
• Available in 10 mg, 20 mg, and 40 mg oral capsules, plus liquid formulation
• Typically administered once daily, with or without food
• Generic versions widely available, improving accessibility
• FDA-approved for multiple psychiatric indications

Benefits

• Significantly reduces symptoms of depression and anxiety
• Helps restore normal sleep, appetite, and energy levels
• Reduces frequency and intensity of panic attacks and obsessive thoughts
• Supports long-term mood stability with consistent use
• Lower risk of certain side effects compared to older antidepressants

Common use

Fluoxetine is primarily used 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 may include treatment of premenstrual dysphoric disorder (PMDD), post-traumatic stress disorder (PTSD), and certain anxiety spectrum conditions, though these should be carefully evaluated by a healthcare provider.

Dosage and direction

Dosage must be individualized based on diagnosis, patient response, and tolerability. For depression in adults, the initial dose is typically 20 mg once daily in the morning, which may be increased after several weeks if needed. Maximum recommended dose is 80 mg/day. For OCD, doses may range from 20–60 mg daily; for bulimia nervosa, 60 mg daily is commonly used. Panic disorder dosing often starts at 10 mg daily to minimize initial anxiety, titrating upward. Always take as prescribed; do not crush, chew, or break capsules. Full therapeutic effect may take 4–6 weeks.

Precautions

Patients should be monitored for clinical worsening, suicidality, or unusual changes in behavior, especially during initial treatment or dose adjustments. Use with caution in those with a history of mania, seizures, or hepatic impairment. May cause hyponatremia, abnormal bleeding, or angle-closure glaucoma. Discontinuation should be gradual to avoid withdrawal symptoms. Not recommended during pregnancy unless potential benefits justify potential risks. Avoid alcohol during treatment.

Contraindications

Fluoxetine is contraindicated in patients taking monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing MAOI therapy due to risk of serotonin syndrome. Contraindicated in those with known hypersensitivity to fluoxetine or any component of the formulation. Should not be used with pimozide or thioridazine due to risk of QT prolongation.

Possible side effects

Common side effects include headache, nausea, insomnia, fatigue, diarrhea, dry mouth, nervousness, and sweating. Sexual dysfunction such as decreased libido or anorgasmia may occur. Less commonly, rash, weight changes, or bruising may present. Rare but serious side effects include serotonin syndrome, suicidal thoughts, seizures, mania, or severe allergic reactions. Most side effects are dose-dependent and may diminish over time.

Drug interaction

Fluoxetine is a strong inhibitor of CYP2D6 and moderate inhibitor of CYP3A4, which may increase levels of co-administered drugs metabolized by these enzymes. Significant interactions occur with MAOIs, other serotonergic drugs, anticoagulants, antiplatelets, NSAIDs, tramadol, triptans, tricyclic antidepressants, antipsychotics, and certain anticonvulsants. Always inform your prescriber 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 of the next dose. Do not double the dose to make up for a missed one. Consistent daily dosing is important to maintain steady-state serum concentrations.

Overdose

Symptoms of overdose may include nausea, vomiting, agitation, restlessness, hypomania, seizures, or serotonin syndrome. No specific antidote exists; provide supportive care and symptomatic treatment. Gastric lavage and activated charcoal may be considered if presented early. Contact poison control or emergency services immediately.

Storage

Store at room temperature (15–30°C or 59–86°F) in a tightly closed container, away from light, moisture, and heat. Keep out of reach of children and pets. Do not use after the expiration date. Properly discard any unused medication.

Disclaimer

This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting, changing, or discontinuing any medication. Individual responses may vary.

Reviews

Clinical studies and meta-analyses consistently support the efficacy and tolerability of fluoxetine for a range of mood and anxiety disorders. Many patients report significant improvement in quality of life with continued use. However, individual experiences with side effects and effectiveness can vary. Always discuss treatment goals and concerns with your prescriber.