Olanzapine and fluoxetine and Viloxazine interaction
Olanzapine and fluoxetine and Viloxazine: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Viloxazine (QELBREE) label · effective 2025-12-05
CYP2D6 Substrates Clinical Impact Viloxazine is a weak inhibitor of CYP2D6, and increases the exposure of CYP2D6 substrates when coadministered [see Clinical Pharmacology (12.3) ] .
From the Olanzapine and fluoxetine label · effective 2026-03-31
Inhibitors of CYP1A2 — Fluvoxamine decreases the clearance of olanzapine.
The effect of CYP1A2 inhibitors, such as fluvoxamine and some fluoroquinolone antibiotics, on olanzapine and fluoxetine capsules has not been evaluated.
Effect of Olanzapine on Drugs Metabolized by Other CYP Enzymes — In vitro studies utilizing human liver microsomes suggest that olanzapine has little potential to inhibit CYP1A2, CYP2C9, and CYP2C19.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.