What the FDA labels say about taking them together
Phenobarbital and verapamil
Verapamil's FDA label of April 6, 2026 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name verapamil. The verapamil label: “Phenobarbital therapy may increase verapamil clearance.”
Check it at the source: the phenobarbital FDA label on DailyMed (effective August 27, 2026); the verapamil FDA label on DailyMed (effective April 6, 2026, Zydus Pharmaceuticals (USA) Inc.).
What does the phenobarbital label say about verapamil?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name verapamil 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 verapamil label say about phenobarbital?
Verapamil label, drug interactionsPhenobarbital: Phenobarbital therapy may increase verapamil clearance.
Source: FDA drug label (Verapamil Hydrochloride, NDA020943), Wilshire Pharmaceuticals, Inc., effective November 27, 2024 (SPL set 5f665d08-e1e4-422a-88c2-d8834abf9e1a), via openFDA
Source: FDA drug label (Verapamil hydrochloride), Zydus Pharmaceuticals (USA) Inc., effective April 6, 2026 (SPL set e19ab8d8-dae5-489d-9805-7e7407bea06d), 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 | Verapamil | |
|---|---|---|
| Labeled for | Seizures and epilepsy | High blood pressure, Atrial fibrillation, Angina |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.213 per tablet 100 mg tablet | $0.191 per tablet 180 mg tablet |
| Shortage now | A presentation being discontinued | A presentation being discontinued |
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