What the FDA labels say about taking them together
Phenytoin and suvorexant
Suvorexant's FDA label of March 10, 2025 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name suvorexant. The suvorexant label: “CYP3A Inducers Suvorexant exposure can be substantially decreased when co-administered with strong CYP3A inducers.”
Check it at the source: the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.); the suvorexant FDA label on DailyMed (effective March 10, 2025, Merck Sharp & Dohme LLC).
What does the phenytoin label say about suvorexant?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name suvorexant 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 suvorexant label say about phenytoin?
Suvorexant label, drug interactionsCYP3A Inducers Suvorexant exposure can be substantially decreased when co-administered with strong CYP3A inducers (e.g., rifampin, carbamazepine and phenytoin).
Source: FDA drug label (BELSOMRA), Merck Sharp & Dohme LLC, effective March 10, 2025 (SPL set e5b72731-1acb-45b7-9c13-290ad12d3951), 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 | Suvorexant | |
|---|---|---|
| Labeled for | Seizures and epilepsy | Insomnia |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.145 per capsule 100 mg capsule | $15.21 per tablet 10 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