What the FDA labels say about taking them together
Divalproex and felbamate
Divalproex's FDA label of March 31, 2026 names felbamate in its drug interactions section; felbamate's label does not name divalproex itself but warns about its class (Anti-seizure medicines). The divalproex label: “DRUG INTERACTIONS Hepatic enzyme-inducing drugs can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance.”
Check it at the source: the divalproex FDA label on DailyMed (effective March 31, 2026, AbbVie Inc.); the felbamate FDA label on DailyMed (effective August 15, 2025, Viatris Specialty LLC).
What does the divalproex label say about felbamate?
Divalproex label, drug interactionsDRUG INTERACTIONS Hepatic enzyme-inducing drugs (e.g., phenytoin, carbamazepine, phenobarbital, primidone, rifampin) can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance.
Source: FDA drug label (Depakote), AbbVie Inc., effective March 31, 2026 (SPL set 08a65cf4-7749-4ceb-6895-8f4805e2b01f), via openFDA; the full label on DailyMed
What does the felbamate label say about divalproex?
Felbamate's label does not name divalproex itself; it warns about its class (Anti-seizure medicines):
Felbamate label, drug interactionsCBZ epoxide ↓ ↑ ↓ Phenobarbital ↑ ↓ Specific Effects of Felbatol® on Other Antiepileptic Drugs Phenytoin Felbatol ® causes an increase in steady-state phenytoin plasma concentrations.
Felbamate label, drug interactionsEffects of Other Antiepileptic Drugs on Felbatol ® Phenytoin Phenytoin causes an approximate doubling of the clearance of Felbatol ® (felbamate) at steady-state and, therefore, the addition of phenytoin causes an approximate 45% decrease in the steady-state trough concentrations of Felbatol ® as compared to the same dose of Felbatol ® given as monotherapy.
Source: FDA drug label (Felbatol), NDA020189 (Mylan Speciality Lp), as published by Viatris Specialty LLC, effective August 15, 2025 (SPL set 2f522701-397a-11de-8a39-0800200c9a66), 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
| Divalproex | Felbamate | |
|---|---|---|
| Labeled for | Bipolar disorder, Migraine, Seizures and epilepsy | Seizures and epilepsy |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.194 per tablet 500 mg tablet | $1.00 per tablet 600 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