What the FDA labels say about taking them together
Phenytoin and ranolazine
Ranolazine's FDA label of January 23, 2026 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name ranolazine. The ranolazine label: “CYP3A Inducers Do not use ranolazine with CYP3A inducers such as rifampin, rifabutin, rifapentine, phenobarbital, phenytoin, carbamazepine, and St. John’s wort.”
Check it at the source: the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.); the ranolazine FDA label on DailyMed (effective January 23, 2026, Glenmark Pharmaceuticals Inc., USA).
What does the phenytoin label say about ranolazine?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name ranolazine 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
What does the ranolazine label say about phenytoin?
Ranolazine label, drug interactionsCYP3A Inducers Do not use ranolazine with CYP3A inducers such as rifampin, rifabutin, rifapentine, phenobarbital, phenytoin, carbamazepine, and St. John’s wort [see Contraindications (4), Clinical Pharmacology (12.3) ].
Source: FDA drug label (Aspruzyo Sprinkle, NDA216018), SUN PHARMACEUTICAL INDUSTRIES, INC., effective January 29, 2025 (SPL set dd9f81e4-50da-4551-aed5-559d304df42e), via openFDA
Source: FDA drug label (Ranolazine), Glenmark Pharmaceuticals Inc., USA, effective January 23, 2026 (SPL set 0cf58732-c242-49b0-8e3f-248778b4458d), 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 | Ranolazine | |
|---|---|---|
| Labeled for | Seizures and epilepsy | Angina |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.145 per capsule 100 mg capsule | $0.165 per tablet 500 mg tablet |
| 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