Drug interactions
Ondansetron + Rifampin
Severity: Moderate
Ondansetron and Rifampin: moderate interaction.
Last updated
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.
Summary
Rifampin strongly induces CYP3A4 and other enzymes, lowering ondansetron levels and potentially its antiemetic effect. Reduced exposure has been shown in pharmacokinetic data.
What this interaction means in plain words
Ondansetron and Rifampin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Induction of CYP3A4 and other hepatic enzymes by rifampin increases ondansetron clearance.
What to do
Monitor antiemetic response and increase the ondansetron dose or use another agent if control is inadequate. Reassess dose after rifampin is stopped.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Ondansetron
- Apomorphine + Ondansetron Contraindicated
- Ondansetron + Thioridazine Contraindicated
- Ondansetron + Vandetanib Contraindicated
- Adagrasib + Ondansetron Major
- Amiodarone + Ondansetron Major
- Amisulpride + Ondansetron Major
Frequently asked questions
Can I take Ondansetron with Rifampin?
MediHelp rates the interaction as moderate. Ondansetron and Rifampin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Rifampin strongly induces CYP3A4 and other enzymes, lowering ondansetron levels and potentially its antiemetic effect. Reduced exposure has been shown in pharmacokinetic data.
How serious is the interaction between Ondansetron and Rifampin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor antiemetic response and increase the ondansetron dose or use another agent if control is inadequate. Reassess dose after rifampin is stopped.
What other medicines interact with Ondansetron?
MediHelp also lists interactions of Ondansetron with, for example, Apomorphine, Thioridazine, Vandetanib. The full list is on the Ondansetron page.
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