Fluoxetine: How It Works, Uses, and Safety

Feeling stuck on meds? Fluoxetine—known as Prozac—is one of the most prescribed antidepressants worldwide. This page gives clear, practical things you need to know: uses, dosing basics, common side effects, interactions, and tips to stay safer.

Uses and how it works

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI). It raises serotonin in the brain to improve mood, reduce panic and obsessive thoughts, and lower binge eating. Doctors prescribe it for major depression, obsessive-compulsive disorder (OCD), panic disorder, bulimia nervosa, and premenstrual dysphoric disorder (PMDD). Expect two to six weeks to notice a reliable change, and sometimes longer for full effect.

Taking fluoxetine safely

Typical adult starting dose is 20 mg once daily. Some people switch to a weekly 90 mg capsule after they respond. Older adults and people with liver problems often start lower. Take it in the morning if it makes you alert, or at night if it causes sleepiness. Don’t stop suddenly; work with your prescriber to taper to avoid withdrawal symptoms like dizziness, electric shock sensations, or mood swings.

Major warning: do not combine fluoxetine with monoamine oxidase inhibitors (MAOIs). That mix can trigger serotonin syndrome, which is life threatening. After stopping an MAOI you normally wait at least two weeks before starting fluoxetine; after fluoxetine, your doctor may recommend a longer gap before an MAOI.

Fluoxetine affects liver enzymes, especially CYP2D6. That can change levels of other drugs, including some heart medicines, certain antipsychotics, and tamoxifen. Talk with your pharmacist about interactions before you add new prescriptions or over-the-counter remedies. Also avoid combining fluoxetine with St. John’s wort or other strong serotonin agents.

Common side effects are nausea, headache, anxiety, trouble sleeping, dry mouth, and sexual side effects such as lower libido or delayed orgasm. Most people find these ease after a few weeks. Serious problems are rare but need prompt action: very high fever, severe stiffness, racing heart, fainting, severe allergic reaction, uncontrolled bleeding, or new suicidal thoughts. If any of these happen, get immediate medical help.

Pregnancy and breastfeeding require a discussion with your clinician. Fluoxetine crosses the placenta and can reach breast milk. Your provider will weigh risks of the medication against risks of untreated depression and may suggest monitoring or alternative treatments.

Practical tips: set a daily reminder, keep a brief symptom log noting sleep and mood, and check progress with your prescriber in two to four weeks. Ask about generic fluoxetine if cost is a concern. Only use licensed pharmacies that require a valid prescription.

Avoid alcohol while starting fluoxetine because it can increase drowsiness and make side effects worse. If sexual side effects are a problem, talk openly — options include dose adjustment, switching drugs, or adding a short-term remedy. When switching antidepressants, expect planning and sometimes a washout period; never change medicines without your prescriber’s guidance.

Keep regular follow ups and report any worrying changes quickly. If you have questions or sudden problems, contact your provider or go to the ER.