5 known interactions • 2 major • 3 moderate • 0 minor
Always disclose all medications to your healthcare providers — prescription medicines, OTC medications, vitamins, and herbal supplements. This list may not include every possible interaction. Use our Medicine Interaction Checker to screen your complete medication list.
Potentially life-threatening or causing permanent damage. Avoid combination.
May worsen condition or require dose adjustment. Monitor closely.
Usually limited clinical effect. Manage with routine monitoring.
MAOIs
Potentially fatal serotonin syndrome. Wait 14 days after stopping MAOI before starting fluoxetine. Wait 5 WEEKS after stopping fluoxetine before starting MAOI (due to very long half-life of norfluoxetine).
Management: ABSOLUTE CONTRAINDICATION. Extended washout period required.
Thioridazine / Pimozide
Fluoxetine inhibits CYP2D6, which metabolizes these antipsychotics, increasing risk of QTc prolongation and potentially fatal arrhythmias.
Management: Contraindicated.
Tamoxifen
Fluoxetine inhibits CYP2D6, reducing conversion of tamoxifen to its active metabolite endoxifen. This could reduce effectiveness of tamoxifen in breast cancer treatment.
Management: Avoid combination if possible; use sertraline (minimal CYP2D6 inhibition) instead.
TCAs (tricyclic antidepressants)
Fluoxetine inhibits CYP2D6, dramatically increasing TCA plasma levels and toxicity risk.
Management: Use combination cautiously if needed; reduce TCA dose by 50–75%; monitor levels.
Codeine / Tramadol
CYP2D6 inhibition reduces conversion of codeine/tramadol to active metabolites, reducing analgesia. Serotonin syndrome risk with tramadol.
Management: Avoid; use alternative opioids not dependent on CYP2D6.
Always ask your pharmacist about potential interactions with food, alcohol, and supplements specific to Fluoxetine. Some medicines have significant interactions with grapefruit juice, high-fat meals, dairy products, or vitamin K-rich foods.