Drug interactions
Fostemsavir + Ondansetron
Severity: Moderate
Fostemsavir and Ondansetron: moderate 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
Ondansetron prolongs the QT interval, and fostemsavir has caused QT prolongation at supratherapeutic doses. At standard doses the added effect is probably small, but the risk rises with other QT risk factors.
What this interaction means in plain words
Fostemsavir and Ondansetron can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fostemsavir belongs to Anti Virals; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive QT prolongation.
What to do
Correct potassium and magnesium and avoid high ondansetron doses. Consider an ECG in patients with long QT, heart disease or other QT-prolonging drugs.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Fostemsavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Fostemsavir with Ondansetron?
MediHelp rates the interaction as moderate. Fostemsavir and Ondansetron can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Ondansetron prolongs the QT interval, and fostemsavir has caused QT prolongation at supratherapeutic doses. At standard doses the added effect is probably small, but the risk rises with other QT risk factors.
How serious is the interaction between Fostemsavir and Ondansetron?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Correct potassium and magnesium and avoid high ondansetron doses. Consider an ECG in patients with long QT, heart disease or other QT-prolonging drugs.
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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