What the FDA labels say about taking them together
Glimepiride and phenytoin
Glimepiride's FDA label of May 12, 2025 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name glimepiride. The glimepiride label: “… corticosteroids, phenothiazines, thyroid hormones, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, and isoniazid.”
Check it at the source: the glimepiride FDA label on DailyMed (effective May 12, 2025, Micro Labs Limited); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the glimepiride label say about phenytoin?
Glimepiride label, drug interactionsThe following are examples of medications that may reduce the glucose-lowering effect of sulfonylureas including glimepiride, leading to worsening glycemic control: danazol, glucagon, somatropin, protease inhibitors, atypical antipsychotic medications (e.g., olanzapine and clozapine), barbiturates, diazoxide, laxatives, rifampin, thiazides and other diuretics, corticosteroids, phenothiazines, thyroid hormones, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics (e.g., epinephrine, albuterol, terbutaline), and isoniazid.
Source: FDA drug label (Glimepiride), Micro Labs Limited, effective May 12, 2025 (SPL set 60e9397e-83b9-489e-9683-6f87e458bbaa), via openFDA; the full label on DailyMed
What does the phenytoin label say about glimepiride?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name glimepiride in these sections. A label lists what its studies and reports found; it is not a complete list.
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
| Glimepiride | Phenytoin | |
|---|---|---|
| Labeled for | Type 2 diabetes | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0507 per tablet 4 mg tablet | $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