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Antidepressant (SSRI - selective serotonin reuptake inhibitor)

Fluoxetine: uses, side effects & precautions

Also known as Prozac, Sarafem.

Diese Informationen dienen ausschließlich der allgemeinen Orientierung und stellen keine medizinische Beratung dar. Konsultieren Sie bei persönlichen gesundheitlichen Anliegen stets eine qualifizierte medizinische Fachkraft. Wählen Sie im Notfall Ihre örtliche Notrufnummer.

What it is used for

  • Depression
  • Obsessive-compulsive disorder (OCD)
  • Bulimia nervosa
  • Panic disorder
  • Premenstrual dysphoric disorder

How it works

Fluoxetine raises the level of serotonin, a mood-related chemical messenger, in the brain by reducing its reuptake into nerve cells. This is thought to gradually lift mood and reduce anxiety and obsessive symptoms.

How it is taken

Usually available as capsules, tablets and an oral liquid, including some longer-acting forms. It is taken by mouth and has a long-lasting effect in the body. Take it exactly as your doctor or pharmacist directs and follow the label; do not adjust or stop it without medical advice.

No doses here on purpose. The right strength and schedule depend on you — only a doctor or pharmacist should set them. Always follow your prescription and the label.

Common side effects

  • Nausea
  • Headache
  • Trouble sleeping
  • Feeling nervous, restless or anxious early on
  • Tiredness or drowsiness
  • Reduced appetite
  • Diarrhoea
  • Dry mouth
  • Sexual difficulties
  • Sweating

Serious effects — get help

  • New or worsening suicidal thoughts, especially early in treatment (seek urgent help)
  • Serotonin syndrome: agitation, fever, fast heartbeat, muscle twitching, confusion
  • Severe allergic reaction (rash, facial or throat swelling, trouble breathing)
  • Unusual bleeding or bruising
  • Seizures
  • Signs of low sodium: confusion, weakness, unsteadiness
  • Switch into mania (racing thoughts, very high energy) in people prone to it

If a reaction is severe — for example trouble breathing, swelling of the face or throat, or collapse — go to the nearest emergency room now or call your local emergency number. Do not wait for an online consultation.

Interactions to watch

  • MAOI antidepressants (must not be combined, including a gap before and after)
  • Other serotonin-raising medicines (triptans, tramadol, St John's Wort, other antidepressants)
  • Blood thinners, aspirin and NSAIDs (bleeding risk)
  • Some heart-rhythm medicines (QT prolongation)
  • Medicines processed by the liver, as fluoxetine can affect their levels
  • Alcohol

Who should take care

  • Tell your clinician if you are pregnant, planning pregnancy or breastfeeding
  • Use with caution with liver problems, epilepsy, bipolar disorder, diabetes or bleeding disorders
  • Because it stays in the body a long time, effects and interactions can persist after stopping
  • Closer monitoring may be needed for people under 25
  • Do not start or stop without medical advice

Frequently asked questions

Why does fluoxetine stay in the body longer than other antidepressants?
Fluoxetine and one of its breakdown products are cleared from the body slowly. This means missing an occasional dose has less immediate effect, but interactions can linger for weeks after stopping. Your clinician keeps this in mind when changing medicines.
How long before I feel better?
It usually takes 4-6 weeks for the full effect on mood. Some early changes may appear sooner. Continue as prescribed and review progress with your clinician.
Can it make me feel more anxious at first?
Some people feel more restless or anxious in the first week or two. This often settles, but tell your clinician if it is severe or does not ease.
Is it safe to stop suddenly?
Because fluoxetine leaves the body slowly, withdrawal effects are often milder than with other SSRIs, but you should still only stop on your clinician's advice.

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