What the FDA labels say about taking them together
Phenytoin and posaconazole
Phenytoin's FDA label of October 15, 2024 names posaconazole in its drug interactions section, and posaconazole's label names phenytoin too. The posaconazole label: “Phenytoin Avoid concomitant use of posaconazole with phenytoin unless the benefit to the patient outweighs the risk.”
Check it at the source: the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.); the posaconazole FDA label on DailyMed (effective August 3, 2026, Aurobindo Pharma Limited).
What does the phenytoin label say about posaconazole?
Phenytoin label, drug interactionsInteracting Agent: Azoles; Examples: Fluconazole, ketoconazole, itraconazole, posaconazole, voriconazole
Source: FDA drug label (Phenytek), Mylan Pharmaceuticals Inc., effective October 15, 2024 (SPL set 0f94c791-8b07-4b41-927e-c9f28bec5f60), via openFDA; the full label on DailyMed
What does the posaconazole label say about phenytoin?
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 interactionsPhenytoin Avoid concomitant use of posaconazole with phenytoin 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
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
| Phenytoin | Posaconazole | |
|---|---|---|
| Labeled for | Seizures and epilepsy | Fungal infections |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.145 per capsule 100 mg capsule | $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