What the FDA labels say about taking them together
Omeprazole and phenytoin
Omeprazole's FDA label of April 22, 2024 names phenytoin in its drug interactions section, and phenytoin's label names omeprazole too. The omeprazole label: “Potential for increased exposure of phenytoin.”
Check it at the source: the omeprazole FDA label on DailyMed (effective April 22, 2024, Apotex Corp); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the omeprazole label say about phenytoin?
Omeprazole label, drug interactionsPhenytoin Clinical Impact: Potential for increased exposure of phenytoin. Intervention: Monitor phenytoin serum concentrations. Dose adjustment may be needed to maintain therapeutic drug concentrations. See prescribing information for phenytoin.
Source: FDA drug label (Omeprazole), Apotex Corp, effective April 22, 2024 (SPL set b83329ac-a65e-b3af-a3fb-c5a6c740e5e7), via openFDA; the full label on DailyMed
What does the phenytoin label say about omeprazole?
Phenytoin label, drug interactionsInteracting Agent: Gastric acid reducing agents; Examples: H 2 antagonists (cimetidine), omeprazole
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
| Omeprazole | Phenytoin | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0295 per capsule 20 mg capsule | $0.145 per capsule 100 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