Prozac (fluoxetine): Uses, Safety and Drug Interactions

Uses and capsule formulation

Prozac contains fluoxetine, a selective serotonin reuptake inhibitor, or SSRI. This summary concerns the conventional oral capsule, including the 20 mg strength in the linked medicine record. The US label includes depression, obsessive-compulsive disorder, bulimia nervosa and panic disorder. Some childhood uses have separate age restrictions and monitoring requirements. UK fluoxetine capsule authorisations differ, so the local product leaflet matters. A capsule strength is not a recommended personal daily dose, and different fluoxetine formulations should not be exchanged without checking the prescription.

Effects and monitoring

Improvement is not immediate. Nausea, disturbed sleep, headache, tremor, sweating and sexual difficulties can occur. Early agitation or a change towards unusually elevated mood needs review. Mood and behaviour should be monitored, particularly in younger people and after treatment changes. New thoughts of self-harm require immediate professional help. Severe allergy, seizures, fainting, or fever with confusion and muscle stiffness also need urgent assessment.

Important medicine interactions

Fluoxetine remains in the body for a long time, so interactions can persist after the last capsule. Monoamine oxidase inhibitors require specialist management and the specified separation intervals; this page does not provide a switching schedule. Other serotonergic medicines, including tramadol and some migraine treatments, can increase serotonin syndrome risk. Aspirin, anti-inflammatory painkillers and anticoagulants can increase bleeding risk. Fluoxetine also inhibits CYP2D6: the UK label highlights reduced activation of tamoxifen and contraindicates combination with metoprolol used for heart failure. The US label contraindicates pimozide and thioridazine. These restrictions should not be reduced to a generic interaction score.

Pregnancy, feeding and treatment changes

Discuss pregnancy plans, pregnancy and breastfeeding with the prescriber. Exposure late in pregnancy can affect the newborn, while untreated illness also has consequences. Fluoxetine and its active metabolite enter milk; a nursing infant may need observation for irritability, poor feeding or poor weight gain. Do not abruptly change treatment on the basis of a summary. A pharmacist should review prescription medicines, over-the-counter pain remedies and supplements together.

Sources

• Prozac oral capsules - US prescribing information - Revised January 2026; SPL version 59; effective 8 January 2026
• Fluoxetine 20 mg capsules - UK SmPC - eMC updated 19 June 2026; UK oral capsule scope

Source check: 30 October 2026. This records a source check, not a clinical review by a doctor or pharmacist. Follow the leaflet supplied with your medicine and seek professional advice for personal treatment.