What the FDA labels say about taking them together
Carmustine and phenytoin
Carmustine's FDA label of April 9, 2026 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name carmustine. The carmustine label: “May lead to reduced efficacy. Phenytoin: Carmustine for Injection may reduce the efficacy of phenytoin.”
Check it at the source: the carmustine FDA label on DailyMed (effective April 9, 2026, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc.); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the carmustine label say about phenytoin?
Carmustine label, drug interactionsMay lead to reduced efficacy. (7.1) Phenytoin: Carmustine for Injection may reduce the efficacy of phenytoin.
Source: FDA drug label (CARMUSTINE), Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc., effective April 9, 2026 (SPL set b9b47082-32ee-4abb-a7b2-52292894d3f8), via openFDA; the full label on DailyMed
What does the phenytoin label say about carmustine?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name carmustine 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
| Carmustine | Phenytoin | |
|---|---|---|
| Labeled for | Leukemia, lymphoma and myeloma | Seizures and epilepsy |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $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