Drug interactions
Ondansetron + Quinidine
Severity: Major
Ondansetron and Quinidine: major 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
Quinidine is a well-known cause of QT prolongation and torsades de pointes, and ondansetron adds to this effect. The combination can increase the risk of life-threatening arrhythmia.
What this interaction means in plain words
Ondansetron and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Ondansetron belongs to Gastrointestinal Tract; Quinidine belongs to Anti Parasitic.
Why it happens
Additive hERG channel blockade; quinidine also inhibits CYP2D6, which may modestly raise ondansetron levels.
What to do
Avoid the combination if an alternative antiemetic is available. If it cannot be avoided, correct electrolytes and monitor the ECG.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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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 Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Ondansetron with Quinidine?
MediHelp rates the interaction as major. Ondansetron and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Quinidine is a well-known cause of QT prolongation and torsades de pointes, and ondansetron adds to this effect. The combination can increase the risk of life-threatening arrhythmia.
How serious is the interaction between Ondansetron and Quinidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if an alternative antiemetic is available. If it cannot be avoided, correct electrolytes and monitor the ECG.
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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