What the FDA labels say about taking them together
Posaconazole and rifabutin
Posaconazole's FDA label of August 3, 2026 names rifabutin in its drug interactions section, and rifabutin's label names posaconazole too. The rifabutin label: “If co-administration of these two drugs cannot be avoided, patients should be monitored for adverse events associated with rifabutin administration, and lack of posaconazole efficacy.”
Check it at the source: the posaconazole FDA label on DailyMed (effective August 3, 2026, Aurobindo Pharma Limited); the rifabutin FDA label on DailyMed (effective September 1, 2026, REMEDYREPACK INC.).
What does the posaconazole label say about rifabutin?
Posaconazole label, drug interactionsInteraction Drug: Rifabutin, phenytoin, efavirenz, cimetidine, esomeprazole*; Interaction: Avoid coadministration unless the benefit outweighs the risks (,)
Noxafil label (Merck Sharp & Dohme LLC, February 13, 2026), drug interactionsRifabutin Avoid concomitant use of posaconazole with rifabutin unless the benefit to the patient outweighs the risk.
Source: FDA drug label (Noxafil, NDA022003), Merck Sharp & Dohme LLC, effective February 13, 2026 (SPL set b073b082-7b57-4423-8c06-4fd4263d6f84), via openFDA
Source: FDA drug label (POSACONAZOLE), Aurobindo Pharma Limited, effective August 3, 2026 (SPL set f8a26673-261c-4e8e-b1e1-9e23aaf7f285), via openFDA; the full label on DailyMed
What does the rifabutin label say about posaconazole?
Rifabutin label, drug interactionsCo-administered drug: Posaconazole; Dosing regimen of co-administered drug: 200 mg once a day for 10 days; Dosing regimen of rifabutin: 300 mg once a day for 17 days; Study population (n): Healthy subjects (8); Effect on rifabutin: ↑ AUC by 72%, ↑ C max by 31%; Effect on co-administered drug: ↓ AUC by 49%, ↓ C max by 43%; Recommendation: If co-administration of these two drugs cannot be avoided, patients should be monitored for adverse events associated with rifabutin administration, and lack of posaconazole efficacy.
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
| Posaconazole | Rifabutin | |
|---|---|---|
| Labeled for | Fungal infections | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $2.03 per tablet 100 mg tablet | $8.14 per capsule 150 mg capsule |
| Shortage now | A presentation being discontinued | 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