Drug interactions
Erythromycin ethylsuccinate + Ondansetron
Severity: Major
Erythromycin ethylsuccinate 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
Erythromycin prolongs the QT interval and ondansetron has a similar effect, so the combination increases the risk of torsades de pointes. Erythromycin also inhibits CYP3A4, which may modestly raise ondansetron exposure.
What this interaction means in plain words
Erythromycin ethylsuccinate 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.
Why it happens
Additive QT prolongation, with possible CYP3A4 inhibition by erythromycin.
What to do
Choose a non-macrolide antibiotic or another antiemetic where feasible. If both are required, check the ECG and correct potassium and magnesium.
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
- Ondansetron 4 mg film-coated tablets - SmPC sections 4.3/4.5 (names the partner; "antibiotics (such as erythromycin)") — electronic medicines compendium (UK SmPC)
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 Erythromycin ethylsuccinate with Ondansetron?
MediHelp rates the interaction as major. Erythromycin ethylsuccinate 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. Erythromycin prolongs the QT interval and ondansetron has a similar effect, so the combination increases the risk of torsades de pointes. Erythromycin also inhibits CYP3A4, which may modestly raise ondansetron exposure.
How serious is the interaction between Erythromycin ethylsuccinate 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: Choose a non-macrolide antibiotic or another antiemetic where feasible. If both are required, check the ECG and correct potassium and magnesium.
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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