Drug interactions
Granisetron + Ondansetron
Severity: Moderate
Granisetron and Ondansetron: 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
Both are 5-HT3 receptor antagonists with a small QT-prolonging effect, and combining them offers no antiemetic advantage. Duplicate therapy may add QT risk without benefit.
What this interaction means in plain words
Granisetron and Ondansetron 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.
Granisetron belongs to Gastrointestinal Tract; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Duplicate 5-HT3 antagonism with additive mild QT prolongation.
What to do
Avoid using two 5-HT3 antagonists together; use one agent and add an antiemetic of a different class if needed. Check ECG if combined in patients with QT risk factors.
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
Other interactions of Granisetron
- Apomorphine + Granisetron Contraindicated
- Amiodarone + Granisetron Major
- Amisulpride + Granisetron Major
- Arsenic trioxide + Granisetron Major
- Artemether / lumefantrine + Granisetron Major
- Artemether + Granisetron Major
Frequently asked questions
Can I take Granisetron with Ondansetron?
MediHelp rates the interaction as moderate. Granisetron and Ondansetron 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. Both are 5-HT3 receptor antagonists with a small QT-prolonging effect, and combining them offers no antiemetic advantage. Duplicate therapy may add QT risk without benefit.
How serious is the interaction between Granisetron and Ondansetron?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid using two 5-HT3 antagonists together; use one agent and add an antiemetic of a different class if needed. Check ECG if combined in patients with QT risk factors.
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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