MajorSSRI×Atypical antipsychotic – thienobenzodiazepine
Updated · Methodology
Mechanism
Fluvoxamine is a potent inhibitor of CYP1A2, the liver enzyme that mainly clears olanzapine (fluvoxamine and olanzapine labels). With fluvoxamine, mean peak olanzapine concentration (Cmax) rose by 54% in female non-smokers and by 77% in male smokers, and the area under the concentration-time curve (AUC) by 52% and 108% (olanzapine label).
Symptoms
Olanzapine adverse effects become stronger: somnolence, dizziness, orthostatic hypotension (a drop in blood pressure on standing), increased appetite and weight gain with longer use.
Management
The pair is not banned. Drugs cleared through CYP1A2 are started at, or brought down to, the lower end of their dose range when given with fluvoxamine; their effects and adverse reactions are then monitored and the dose is lowered further if needed (fluvoxamine SmPC). If the patient already takes fluvoxamine, olanzapine is started at a lower dose; if fluvoxamine is added to olanzapine, a lower olanzapine dose is considered (olanzapine SmPC). The US Food and Drug Administration (FDA) olanzapine label also advises lower olanzapine doses with fluvoxamine.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Zyprexa (olanzapine) prescribing information (2009)
- AEMPS: Ficha técnica Dumirox 100 mg (fluvoxamina) (2026)– AEMPS CIMA, Dumirox 100 mg comprimidos recubiertos con película, nº registro 58212, secciones 4.3 y 4.5
- AEMPS: Ficha técnica: Olanzapina (nº registro 85119), sección 4.5 (2026)– AEMPS, CIMA, nº registro 85119, revisión 09/2026, sección 4.5