Felbamate and Phenobarbital Interaction
Drug interaction information between Felbamate and Phenobarbital.
Felbamate and Phenobarbital have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Felbamate and Phenobarbital. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Felbamate causes the level of phenobarbital in your blood to rise.
FDA Label Information
CBZ epoxide ↓ ↑ ↓ Phenobarbital ↑ ↓ Specific Effects of Felbamate on Other Antiepileptic Drugs Phenytoin Felbamate causes an increase in steady-state phenytoin plasma concentrations. Phenobarbital Coadministration of felbamate with phenobarbital causes an increase in phenobarbital plasma concentrations. In 12 otherwise healthy male volunteers ingesting phenobarbital, the steady-state trough (C min ) phenobarbital concentration was 14.2 micrograms/mL.
Felbamate Also Interacts With
- Clonazepam major
- Erythromycin minor
- Carbamazepine minor
- Drospirenone/Ethinyl Estradiol minor
- Estradiol minor
Phenobarbital Also Interacts With
- Nirmatrelvir/Ritonavir major
- Ranolazine major
- Voriconazole major
- Canagliflozin moderate
- Cenobamate moderate
Frequently Asked Questions
What SPL severity band is on file for Felbamate + Phenobarbital?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Phenobarbital has 59 labeled pairs on file vs Felbamate's 16. In the minor band specifically: Felbamate has 15 (also Erythromycin, Carbamazepine, Drospirenone, Estradiol); Phenobarbital has 43 (also Estradiol, Doxycycline, Progesterone, Griseofulvin).
What mechanism field is on file for Felbamate and Phenobarbital?
Felbamate causes the level of phenobarbital in your blood to rise.
Phenobarbital carries more major-labeled pairs than Felbamate
SPL source-record counts only. This page's band is minor · classes on file: Felbamate (Anticonvulsant); Phenobarbital (Anticonvulsant (Barbiturate)).
Phenobarbital has 3 major-labeled pairs vs Felbamate's 1. This page itself is in the minor band, not the major band.
1 major · 0 moderate · 15 minor · 16 total
- Other minor peers for Felbamate
- Erythromycin
- Carbamazepine
- Drospirenone
- Estradiol
3 major · 13 moderate · 43 minor · 59 total
- Other minor peers for Phenobarbital
- Estradiol
- Doxycycline
- Progesterone
- Griseofulvin
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.