What the FDA labels say about taking them together
Efavirenz and posaconazole
Efavirenz's FDA label of March 31, 2024 names posaconazole in its drug interactions section, and posaconazole's label names efavirenz too. The efavirenz label: “Efavirenz and voriconazole should not be coadministered at standard doses. When voriconazole is coadministered with efavirenz, voriconazole maintenance dose should be increased to 400 mg every 12 hours and efavirenz …”
Check it at the source: the efavirenz FDA label on DailyMed (effective March 31, 2024, Cipla USA Inc.); the posaconazole FDA label on DailyMed (effective August 3, 2026, Aurobindo Pharma Limited).
What does the efavirenz label say about posaconazole?
Efavirenz label, drug interactionsConcomitant Drug Class/Drug Name: Antifungals: Voriconazole Itraconazole Ketoconazole Posaconazole; Effect: ↓ voriconazole * ↑ efavirenz * ↓ itraconazole * ↓ hydroxy itraconazole * ↓ ketoconazole ↓ posaconazole *; Clinical Comment: Efavirenz and voriconazole should not be coadministered at standard doses. When voriconazole is coadministered with efavirenz, voriconazole maintenance dose should be increased to 400 mg every 12 hours and efavirenz dose should be decreased to 300 mg once daily using the capsule formulation. Efavirenz tablets must not be broken. [see Dosage and Administration () and Clinical Pharmacology (, and)]. …
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 posaconazole label say about efavirenz?
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 interactionsPrevention or Management Efavirenz Avoid concomitant use of posaconazole with efavirenz, unless the benefit outweighs the risks.
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
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 | Posaconazole | |
|---|---|---|
| Labeled for | HIV | Fungal infections |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $1.28 per tablet 600 mg tablet | $2.03 per tablet 100 mg tablet |
| Shortage now | No current entry | A presentation being discontinued |
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