What the FDA labels say about taking them together
Efavirenz and rifabutin
Efavirenz's FDA label of March 31, 2024 names rifabutin in its drug interactions section; the rifabutin label PlainMeds reads does not name efavirenz. The efavirenz label: “Increase daily dose of rifabutin by 50%. Consider doubling the rifabutin dose in regimens where rifabutin is given 2 or 3 times a week. …”
Check it at the source: the efavirenz FDA label on DailyMed (effective March 31, 2024, Cipla USA Inc.); the rifabutin FDA label on DailyMed (effective September 1, 2026, REMEDYREPACK INC.).
What does the efavirenz label say about rifabutin?
Efavirenz label, drug interactionsConcomitant Drug Class/Drug Name: Antimycobacterial: Rifabutin Rifampin; Effect: ↓ rifabutin * ↓ efavirenz *; Clinical Comment: Increase daily dose of rifabutin by 50%. Consider doubling the rifabutin dose in regimens where rifabutin is given 2 or 3 times a week. Increase efavirenz to 800 mg once daily when coadministered with rifampin to patients weighing 50 kg or more.
Source: FDA drug label (Efavirenz), Cipla USA Inc., effective March 31, 2024 (SPL set 92603fa5-7a2c-4bfb-9a70-aadb4fba952c), via openFDA; the full label on DailyMed
What does the rifabutin label say about efavirenz?
Rifabutin's label (effective September 1, 2026) does not name efavirenz in these sections. A label lists what its studies and reports found; it is not a complete list.
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
| Efavirenz | Rifabutin | |
|---|---|---|
| Labeled for | HIV | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $1.28 per tablet 600 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