Drug interactions
Ondansetron + Pentamidine
Severity: Major
Ondansetron and Pentamidine: 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
Pentamidine, especially when given intravenously, can prolong the QT interval and cause torsades de pointes. Adding ondansetron increases the cumulative effect on repolarisation.
What this interaction means in plain words
Ondansetron and Pentamidine 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; Pentamidine belongs to Anti Parasitic.
Why it happens
Additive pharmacodynamic QT prolongation.
What to do
Use an alternative antiemetic where possible. If both are needed, monitor ECG and correct potassium and magnesium before and during therapy.
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 Pentamidine
- Clomipramine + Pentamidine Contraindicated
- Desipramine + Pentamidine Contraindicated
- Dronedarone + Pentamidine Contraindicated
- Moxifloxacin + Pentamidine Contraindicated
- Nortriptyline + Pentamidine Contraindicated
- Pentamidine + Pimozide Contraindicated
Frequently asked questions
Can I take Ondansetron with Pentamidine?
MediHelp rates the interaction as major. Ondansetron and Pentamidine 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. Pentamidine, especially when given intravenously, can prolong the QT interval and cause torsades de pointes. Adding ondansetron increases the cumulative effect on repolarisation.
How serious is the interaction between Ondansetron and Pentamidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use an alternative antiemetic where possible. If both are needed, monitor ECG and correct potassium and magnesium before and during therapy.
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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