--- title: "Fluoxetine: Uses & Side Effects | HealthAnswers" description: "Fluoxetine (Prozac) is a long-acting SSRI antidepressant used for depression, bulimia and some anxiety disorders, with a slower withdrawal profile." url: https://healthanswers.co.uk/treatments/fluoxetine/ robots: noindex --- # Fluoxetine: Uses & Side Effects | HealthAnswers Treatments Fluoxetine (Prozac) is a long-acting SSRI antidepressant used for depression, bulimia and some anxiety disorders, with a slower withdrawal profile. Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026 ## Quick answer What is fluoxetine used for? Fluoxetine is a long half-life SSRI antidepressant used to treat depression, bulimia and some anxiety disorders. Its activating effect may suit people with low energy, though this can also cause insomnia. Because it clears from the body slowly, withdrawal symptoms tend to be less abrupt, but you should still taper it under GP guidance. ## Who is this page for? This page is for people in the UK who want a plain-English overview of Fluoxetine, including when to seek help and what NHS care usually involves. It explains general information, not what is wrong with you personally. ## Who should skip this page? Skip this page if you need a diagnosis, a prescription, or emergency care. It cannot replace a GP, pharmacist, NHS 111 or 999. If you are in immediate danger, call 999; for urgent advice that is not life-threatening, call 111 in England, Scotland or Wales, or use your GP out-of-hours service in Northern Ireland. On this page 4 sections ## Key facts about fluoxetine - Fluoxetine has a long half-life, so missed doses are less critical than with other SSRIs. - It has an activating effect and may cause insomnia in some people. - It is used as a treatment for bulimia nervosa. - It interacts with other medicines through the CYP450 liver enzyme system. - It should be used with caution in people with bipolar disorder, as it can trigger mania. ## Fluoxetine profile Fluoxetine is one of the oldest SSRIs and is well studied, having been used in clinical practice for many years. Its long duration of action comes from an active metabolite that persists in the body after the original dose. ## What fluoxetine is used for Fluoxetine is licensed for depression, obsessive-compulsive disorder (OCD), bulimia and panic disorder. In children and adolescents, treatment for depression is usually started by a specialist. ## Side effects of fluoxetine In the early stages of treatment, fluoxetine can cause insomnia, anxiety and gastrointestinal upset. Sexual dysfunction and sweating are also reported side effects. ## Monitoring while taking fluoxetine Mood should be monitored closely, particularly in anyone with a history of bipolar disorder, as fluoxetine can trigger mania. Because it interacts with a wide range of other medicines, a full review of your current medicines is recommended before and during treatment. ## ! Important safety information for fluoxetine See your GP before starting or stopping fluoxetine. Report mania, a severe rash, or suicidal thoughts to a doctor urgently. Call **111** for urgent advice when you are unsure what to do. ## Common questions about fluoxetine Should I take fluoxetine in the morning or evening? Fluoxetine is often taken in the morning because of its activating effect, which can otherwise disturb sleep. If you notice insomnia, avoid taking your dose later in the day. Is fluoxetine easier to stop than other antidepressants? Fluoxetine's long half-life means it can leave the body more gradually, which makes withdrawal smoother for some people compared with shorter-acting SSRIs. It should still be tapered under medical supervision rather than stopped abruptly. Is fluoxetine safe to take during pregnancy? The risks and benefits of taking fluoxetine in pregnancy need to be weighed up individually. If you are pregnant or planning a pregnancy, seek specialist advice before starting or stopping treatment. Can I take fluoxetine with tamoxifen? Fluoxetine should generally be avoided with tamoxifen because it can interfere with how tamoxifen works. An alternative SSRI is usually used instead for breast cancer survivors who need an antidepressant. ## Sources - [NHS — Fluoxetine](https://www.nhs.uk/medicines/fluoxetine) - [NHS — Bulimia](https://www.nhs.uk/conditions/bulimia)