What the FDA labels say about taking them together
Mexiletine and phenytoin
Mexiletine's FDA label of May 14, 2026 names phenytoin in its drug interactions section, and phenytoin's label names mexiletine too. The phenytoin label: “Interacting Agent: Other; Examples: Albendazole, chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine”
Check it at the source: the mexiletine FDA label on DailyMed (effective May 14, 2026, Macleods Pharmaceuticals Limited); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the mexiletine label say about phenytoin?
Mexiletine label, drug interactionsWhen phenytoin or other hepatic enzyme inducers such as rifampin and phenobarbital have been taken concurrently with mexiletine, lowered mexiletine plasma levels have been reported.
Source: FDA drug label (Mexiletine Hydrochloride), Macleods Pharmaceuticals Limited, effective May 14, 2026 (SPL set a61a07f6-0b48-4dcd-ad42-5d90f6e69ab1), via openFDA; the full label on DailyMed
What does the phenytoin label say about mexiletine?
Phenytoin label, drug interactionsInteracting Agent: Other; Examples: Albendazole (decreases active metabolite), chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine
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
| Mexiletine | Phenytoin | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.222 per capsule 150 mg capsule | $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