What the FDA labels say about taking them together
Colesevelam and phenytoin
Colesevelam's FDA label of December 28, 2023 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name colesevelam. The colesevelam label: “There have been postmarketing reports of increased seizure activity or decreased phenytoin levels in patients receiving phenytoin.”
Check it at the source: the colesevelam FDA label on DailyMed (effective December 28, 2023, A-S Medication Solutions); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the colesevelam label say about phenytoin?
Colesevelam label, drug interactionsPhenytoin Clinical Impact: There have been postmarketing reports of increased seizure activity or decreased phenytoin levels in patients receiving phenytoin. Intervention: Administer phenytoin 4 hours prior to colesevelam hydrochloride.
Source: FDA drug label (COLESEVELAM HYDROCHLORIDE), NDA021176 (Cosette), as published by A-S Medication Solutions, effective December 28, 2023 (SPL set 0127afae-8d8d-43f2-97f9-4f99f6947e81), via openFDA; the full label on DailyMed
What does the phenytoin label say about colesevelam?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name colesevelam 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
| Colesevelam | Phenytoin | |
|---|---|---|
| Labeled for | High cholesterol, Type 2 diabetes | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.262 per tablet 625 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