Drug interactions
Haloperidol + Ondansetron
Severity: Major
Haloperidol and Ondansetron: 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
Both drugs prolong the QT interval, and haloperidol, especially intravenously or at high dose, has been linked with torsades de pointes. Adding ondansetron increases the arrhythmic risk, notably with electrolyte disturbances or cardiac disease.
What this interaction means in plain words
Haloperidol and Ondansetron 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.
Haloperidol belongs to Central Nervous System; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive hERG potassium channel blockade causing delayed repolarization.
What to do
Obtain a baseline ECG, correct potassium and magnesium, and monitor QTc. Use a lower-risk antiemetic if QTc is prolonged or there is congenital long QT syndrome.
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 Haloperidol
- Dofetilide + Haloperidol Contraindicated
- Dronedarone + Haloperidol Contraindicated
- Haloperidol + Ibutilide Contraindicated
- Haloperidol + Levoketoconazole Contraindicated
- Haloperidol + Panobinostat Contraindicated
- Haloperidol + Pimozide Contraindicated
Frequently asked questions
Can I take Haloperidol with Ondansetron?
MediHelp rates the interaction as major. Haloperidol and Ondansetron 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. Both drugs prolong the QT interval, and haloperidol, especially intravenously or at high dose, has been linked with torsades de pointes. Adding ondansetron increases the arrhythmic risk, notably with electrolyte disturbances or cardiac disease.
How serious is the interaction between Haloperidol and Ondansetron?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG, correct potassium and magnesium, and monitor QTc. Use a lower-risk antiemetic if QTc is prolonged or there is congenital long QT syndrome.
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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