Drug interactions
Ondansetron + Phenobarbital
Severity: Minor
Ondansetron and Phenobarbital: minor 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
Phenobarbital is an inducer of CYP3A4 and other enzymes and may lower ondansetron exposure. The effect is generally modest and rarely requires a change in therapy.
What this interaction means in plain words
Ondansetron and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Hepatic enzyme induction by phenobarbital increases ondansetron clearance.
What to do
No routine dose adjustment is needed. Reassess antiemetic efficacy and increase dosing or change agent if nausea persists.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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 Phenobarbital?
MediHelp rates the interaction as minor. Ondansetron and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenobarbital is an inducer of CYP3A4 and other enzymes and may lower ondansetron exposure. The effect is generally modest and rarely requires a change in therapy.
How serious is the interaction between Ondansetron and Phenobarbital?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine dose adjustment is needed. Reassess antiemetic efficacy and increase dosing or change agent if nausea persists.
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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