Can fluoxetine cause weight gain?

While weight gain is not a common side effect of fluoxetine (brand name Prozac), it can occur in some patients. However, it is more common for fluoxetine to cause weight loss or have no effect on weight.

A study published in the Journal of Clinical Psychiatry found that about 25% of patients taking fluoxetine experienced weight changes, with some gaining weight and others losing weight. However, the overall effect on weight was small, with an average change of less than 2 pounds.

It is thought that the effect of fluoxetine on weight is related to its impact on appetite and metabolism. Some patients may experience increased appetite or cravings for high-calorie foods while taking the medication, which can lead to weight gain. However, others may experience decreased appetite or nausea, which can lead to weight loss.

If you are concerned about weight changes while taking fluoxetine, it’s important to talk to your healthcare provider. They can provide guidance on how to manage any changes in weight and may adjust your dosage or switch you to a different medication if necessary. It’s also important to maintain a healthy diet and exercise regularly to promote overall health and well-being.


There are various forms of drugs available, such as tablets or liquids, and each may have a separate patient information leaflet (PIL) for different doses. It is important to refer to the PIL for the specific form and dose of the drug that you have been prescribed.

You can search for further information and PILs on websites such as:

  • The British National Formulary (BNF)
  • Electronic medicines compendium (emc)
  • The National Library of Medicine's DailyMed
  • The Food and Drug Administration (FDA) 
  • Different drug forms like tablets or liquids have specific patient information leaflets (PIL) for various doses. Refer to the PIL for your prescribed drug form and dose.

    Search for PILs on websites like:

    France

    • ANSM (Agence nationale de sécurité du médicament et des produits de santé): ansm.sante.fr

    Spain

    • AEMPS (Agencia Española de Medicamentos y Productos Sanitarios): aemps.gob.es

    Germany

    • BfArM (Bundesinstitut für Arzneimittel und Medizinprodukte): bfarm.de

    Italy

    For questions about your medication:

    • Consult your doctor, a healthcare professional, or a pharmacist

    France

    • Contact SOS Médecins: 3624
    • For mental health support, contact SOS Suicide: 01 45 39 40 00

    Belgium (French)

    Switzerland (French)

    • La Main Tendue: 143
    • Website: 143.ch

    Canada (French)

    • Centre de prévention du suicide du Québec: 1 866 APPELLE (1 866 277-3553)
    • Website: cpsquebec.ca

    Spain

    • Contact emergency number: 112
    • For mental health support, contact Teléfono de la Esperanza: 717 003 717

    Germany

    • Contact emergency number: 112
    • For mental health support, contact Telefonseelsorge: 0800 111 0 111 or 0800 111 0 222

    Italy

    • Contact emergency number: 112
    • For mental health support, contact Telefono Amico: 199 284 284

    Netherlands

    • Contact emergency number: 112
    • For mental health support, contact 113 Zelfmoordpreventie: 0800 0113

    Portugal

    • Contact emergency number: 112
    • For mental health support, contact Sos Voz Amiga: 21 354 45 45, 91 280 26 69, or 96 352 46 60

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