What the FDA labels say about taking them together
Phenobarbital and rufinamide
Rufinamide's FDA label of December 15, 2022 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name rufinamide. The rufinamide label: “AED Co-administered: Phenobarbital; Influence of Rufinamide on AED concentration a): Increase by 8 to 13% b); Influence of AED on Rufinamide concentration: Decrease by 25 to 46% c) ’ d) Independent of dose or …”
Check it at the source: the phenobarbital FDA label on DailyMed (effective August 27, 2026); the rufinamide FDA label on DailyMed (effective December 15, 2022, Eisai Inc.).
What does the phenobarbital label say about rufinamide?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name rufinamide in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Phenobarbital), Chartwell RX, LLC, effective August 27, 2026 (SPL set 74428144-fb24-40a5-a670-3b876e2d116c), via openFDA; the full label on DailyMed
What does the rufinamide label say about phenobarbital?
Rufinamide label, drug interactionsAED Co-administered: Phenobarbital; Influence of Rufinamide on AED concentration a): Increase by 8 to 13% b); Influence of AED on Rufinamide concentration: Decrease by 25 to 46% c) ’ d) Independent of dose or concentration of phenobarbital
Source: FDA drug label (Banzel), Eisai Inc., effective December 15, 2022 (SPL set 0a3fa925-1abd-458a-bd57-4ae780a1ef2d), 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
| Phenobarbital | Rufinamide | |
|---|---|---|
| Labeled for | Seizures and epilepsy | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.213 per tablet 100 mg tablet | $0.203 per mL 40 mg/mL suspension |
| Shortage now | A presentation being discontinued | 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