What the FDA labels say about taking them together
Deflazacort and phenytoin
Deflazacort's FDA label of November 13, 2025 names phenytoin in its drug interactions section; phenytoin's label does not name deflazacort itself but warns about its class (Corticosteroids). The deflazacort label: “Avoid concomitant use of strong (e.g., efavirenz) or moderate CYP3A4 inducers with EMFLAZA.”
Check it at the source: the deflazacort FDA label on DailyMed (effective November 13, 2025, PTC Therapeutics, Inc.); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the deflazacort label say about phenytoin?
Deflazacort label, drug interactionsAvoid concomitant use of strong (e.g., efavirenz) or moderate (e.g., carbamazepine, phenytoin) CYP3A4 inducers with EMFLAZA [see Dosage and Administration ( 2.5 ) and Clinical Pharmacology ( 12.3 )].
Source: FDA drug label (EMFLAZA), PTC Therapeutics, Inc., effective November 13, 2025 (SPL set 31b347d2-f156-4055-9d8f-7cf0df420296), via openFDA; the full label on DailyMed
What does the phenytoin label say about deflazacort?
Phenytoin's label does not name deflazacort itself; it warns about its class (Corticosteroids):
Phenytoin label, drug interactionsWarfarin Increased and decreased PT/INR responses have been reported when phenytoin is coadministered with warfarin Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D Drugs whose level is decreased by phenytoin Anticoagulants Apixaban, dabigatran, edoxaban, rivaroxaban Antiepileptic drugs The effect of phenytoin on phenobarbital, valproic acid and sodium valproate serum levels is unpredictable Carbamazepine …
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
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
| Deflazacort | Phenytoin | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.145 per capsule 100 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