Drug interactions
Foscarnet + Ondansetron
Severity: Major
Foscarnet 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 agents can prolong the QT interval, and foscarnet also commonly causes hypocalcemia, hypomagnesemia and hypokalemia that further predispose to arrhythmia. Together they may increase the risk of torsades de pointes.
What this interaction means in plain words
Foscarnet 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.
Foscarnet belongs to Anti Virals; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive QT prolongation, compounded by foscarnet-induced electrolyte depletion.
What to do
Monitor ECG and serum calcium, magnesium and potassium, correcting abnormalities promptly. Prefer an alternative antiemetic if QTc is prolonged or electrolytes are unstable.
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 Ondansetron
- Apomorphine + Ondansetron Contraindicated
- Ondansetron + Thioridazine Contraindicated
- Ondansetron + Vandetanib Contraindicated
- Adagrasib + Ondansetron Major
- Amiodarone + Ondansetron Major
- Amisulpride + Ondansetron Major
Other interactions of Foscarnet
- Cidofovir + Foscarnet Contraindicated
- Foscarnet + Pimozide Contraindicated
- Foscarnet + Thioridazine Contraindicated
- Foscarnet + Vandetanib Contraindicated
- Adagrasib + Foscarnet Major
- Adefovir + Foscarnet Major
Frequently asked questions
Can I take Foscarnet with Ondansetron?
MediHelp rates the interaction as major. Foscarnet 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 agents can prolong the QT interval, and foscarnet also commonly causes hypocalcemia, hypomagnesemia and hypokalemia that further predispose to arrhythmia. Together they may increase the risk of torsades de pointes.
How serious is the interaction between Foscarnet 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: Monitor ECG and serum calcium, magnesium and potassium, correcting abnormalities promptly. Prefer an alternative antiemetic if QTc is prolonged or electrolytes are unstable.
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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