What the FDA labels say about taking them together
Doravirine and rifabutin
Doravirine's FDA label of July 8, 2026 names rifabutin in its drug interactions section, and rifabutin's label names doravirine too. The doravirine label: “Increase PIFELTRO dosage to one tablet twice daily when co-administered with rifabutin.”
Check it at the source: the doravirine FDA label on DailyMed (effective July 8, 2026, Merck Sharp & Dohme LLC); the rifabutin FDA label on DailyMed (effective September 1, 2026, REMEDYREPACK INC.).
What does the doravirine label say about rifabutin?
Doravirine label, drug interactionsConcomitant Drug Class/Drug Name: rifabutin; Effect on Concentration: ↓ doravirine; Clinical Comment: Increase PIFELTRO dosage to one tablet twice daily when co-administered with rifabutin [see ].
Source: FDA drug label (PIFELTRO), Merck Sharp & Dohme LLC, effective July 8, 2026 (SPL set 76ce1f00-28c0-4314-bd2c-d473fe3d0970), via openFDA; the full label on DailyMed
What does the rifabutin label say about doravirine?
Rifabutin label, drug interactionsCo-administered drug: Doravirine; Dosing regimen of co-administered drug: 100 mg single dose; Dosing regimen of rifabutin: 300 mg once a day for 16 days; Study population (n): Healthy subjects (12); Effect on rifabutin: ND; Effect on co-administered drug: ↓ 50% in AUC, ↓ 68% in C 24 ↔ in C max; Recommendation: If concomitant use is necessary, increase the doravirine dosage as instructed in doravirine-containing product prescribing information.
Rifabutin label, warningsCo-administration with antiretroviral drugs metabolized by CYP3A, including but not limited to products containing bictegravir, elvitegravir, oral rilpivirine, or doravirine and anti-HCV drugs including but not limited to sofosbuvir (alone or in combination) may decrease plasma concentrations of those drugs, which may lead to loss of virologic response and possible development of resistance.
Source: FDA drug label (Rifabutin), NDA050689 (Pfizer), as published by REMEDYREPACK INC., effective September 1, 2026 (SPL set 25a60937-cbbe-4a50-994f-2ce15203f589), 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
| Doravirine | Rifabutin | |
|---|---|---|
| Labeled for | HIV | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $60.79 per tablet 100 mg tablet | $8.14 per capsule 150 mg capsule |
| Shortage now | No current entry | No current entry |
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