Drug interactions
Fostemsavir + Rifampicin
Severity: Contraindicated
Fostemsavir and Rifampicin: contraindicated 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
Rifampicin markedly reduces temsavir, the active moiety of fostemsavir. This can cause loss of HIV virologic suppression and resistance.
What this interaction means in plain words
Fostemsavir and Rifampicin are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Fostemsavir belongs to Anti Virals; Rifampicin belongs to Anti Bacterial.
Why it happens
Rifampicin induces CYP3A4, increasing temsavir clearance.
What to do
Do not co-administer; use an alternative TB regimen or HIV regimen.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Efavirenz + Fostemsavir Major
Other interactions of Rifampicin
- Cabotegravir + Rifampicin Contraindicated
- Delamanid + Rifampicin Contraindicated
- Doravirine + Rifampicin Contraindicated
- Ensitrelvir + Rifampicin Contraindicated
- Isavuconazole + Rifampicin Contraindicated
- Isavuconazonium + Rifampicin Contraindicated
Frequently asked questions
Can I take Fostemsavir with Rifampicin?
MediHelp rates the interaction as contraindicated. Fostemsavir and Rifampicin are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Rifampicin markedly reduces temsavir, the active moiety of fostemsavir. This can cause loss of HIV virologic suppression and resistance.
How serious is the interaction between Fostemsavir and Rifampicin?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not co-administer; use an alternative TB regimen or HIV regimen.
What other medicines interact with Fostemsavir?
MediHelp also lists interactions of Fostemsavir with, for example, Apalutamide, Carbamazepine, Enzalutamide. The full list is on the Fostemsavir page.
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