Drug interactions
Dolasetron + Ondansetron
Severity: Major
Dolasetron and Ondansetron: major interaction.
Last updated Sources: UK SmPC
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 antagonists that prolong the QT interval in a dose-related manner, and they have no rationale for combined use. Using both increases the risk of torsades de pointes without added antiemetic benefit.
What this interaction means in plain words
Dolasetron 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.
Dolasetron belongs to Gastrointestinal Tract; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive QT prolongation through blockade of cardiac ion channels, a class effect of 5-HT3 antagonists.
What to do
Avoid using two 5-HT3 antagonists together and use an antiemetic from a different class for breakthrough nausea. Correct potassium and magnesium and monitor the ECG if exposure overlaps.
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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References
Other interactions of Dolasetron
- Apomorphine + Dolasetron Contraindicated
- Dofetilide + Dolasetron Contraindicated
- Dolasetron + Ibutilide Contraindicated
- Dolasetron + Pimozide Contraindicated
- Dolasetron + Thioridazine Contraindicated
- Dolasetron + Vandetanib Contraindicated
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 Dolasetron with Ondansetron?
MediHelp rates the interaction as major. Dolasetron 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 are 5-HT3 antagonists that prolong the QT interval in a dose-related manner, and they have no rationale for combined use. Using both increases the risk of torsades de pointes without added antiemetic benefit.
How serious is the interaction between Dolasetron 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: Avoid using two 5-HT3 antagonists together and use an antiemetic from a different class for breakthrough nausea. Correct potassium and magnesium and monitor the ECG if exposure overlaps.
What other medicines interact with Dolasetron?
MediHelp also lists interactions of Dolasetron with, for example, Apomorphine, Dofetilide, Ibutilide. The full list is on the Dolasetron page.
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