Drug interactions
Fluoxetine + Ondansetron
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Overview
Additive QTc prolongation risk; fluoxetine’s CYP2D6 inhibition can increase ondansetron exposure, further elevating QT risk. Rare serotonin-toxicity signals have been reported.
Mechanism of action
Pharmacodynamic additive QT prolongation; pharmacokinetic increase of ondansetron via CYP2D6 inhibition.
Clinical management
Avoid in congenital long-QT or recent TdP; correct potassium/magnesium; use the lowest effective ondansetron dose; consider baseline/periodic ECG if cardiac risk factors are present.
Drug reference
References
- Zofran (ondansetron) Prescribing Information — FDA Label
- Prozac (fluoxetine) Prescribing Information — FDA Label
- Ondansetron + Selective Serotonin Reuptake Inhibitors (Drug Interactions) — Lexicomp
- Causes of QT prolongation and torsades de pointes — UpToDate
Frequently asked questions
Can I take Fluoxetine with Ondansetron?
The interaction is rated: Moderate. Additive QTc prolongation risk; fluoxetine’s CYP2D6 inhibition can increase ondansetron exposure, further elevating QT risk. Rare serotonin-toxicity signals have been reported.
How serious is the interaction between Fluoxetine and Ondansetron?
The interaction is rated: Moderate. Evidence level: Moderate.
How is the interaction between Fluoxetine and Ondansetron managed?
Avoid in congenital long-QT or recent TdP; correct potassium/magnesium; use the lowest effective ondansetron dose; consider baseline/periodic ECG if cardiac risk factors are present.
Why do Fluoxetine and Ondansetron interact?
Pharmacodynamic additive QT prolongation; pharmacokinetic increase of ondansetron via CYP2D6 inhibition.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.