What the FDA labels say about taking them together
Fostemsavir and rifampin
Fostemsavir's FDA label of February 13, 2024 names rifampin in its contraindications section, and rifampin's label names fostemsavir too. The fostemsavir label: “Drugs to Affect RUKOBIA Coadministration of RUKOBIA with rifampin, a strong CYP3A4 inducer, significantly decreases temsavir plasma concentrations.”
Check it at the source: the fostemsavir FDA label on DailyMed (effective February 13, 2024, ViiV Healthcare Company); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the fostemsavir label say about rifampin?
Fostemsavir label, contraindicationsEnzalutamide o Anticonvulsants: Carbamazepine, phenytoin o Antimycobacterial: Rifampin o Antineoplastic:
Fostemsavir label, drug interactionsDrugs to Affect RUKOBIA Coadministration of RUKOBIA with rifampin, a strong CYP3A4 inducer, significantly decreases temsavir plasma concentrations.
Source: FDA drug label (Rukobia), ViiV Healthcare Company, effective February 13, 2024 (SPL set a21006b7-6d6f-4f06-81b4-17978756452b), via openFDA; the full label on DailyMed
What does the rifampin label say about fostemsavir?
Rifampin label, contraindicationsRifampin is contraindicated in patients who are also receiving atazanavir, darunavir, fosamprenavir, saquinavir, tipranavir, cabotegravir, fostemsavir and lenacapavir (see prescribing information for SUNLENCA) due to the potential of rifampin to substantially decrease plasma concentrations of these antiviral drugs, which may result in decreased antiviral efficacy and/or development of viral resistance. (See PRECAUTIONS, Drug Interactions ).
Source: FDA drug label (rifampin), Lupin Pharmaceuticals, Inc., effective February 11, 2026 (SPL set b56004f0-f23d-47f6-80c7-39884fccbccc), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Fostemsavir | Rifampin | |
|---|---|---|
| Labeled for | HIV | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $156.84 per tablet 600 mg tablet | $0.679 per capsule 300 mg capsule |
| Shortage now | No current entry | In shortage |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once