What the FDA labels say about taking them together
Clarithromycin and phenobarbital
Clarithromycin's FDA label of April 9, 2026 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name clarithromycin.
Check it at the source: the clarithromycin FDA label on DailyMed (effective April 9, 2026, Solaris Pharma Corporation); the phenobarbital FDA label on DailyMed (effective August 27, 2026).
What does the clarithromycin label say about phenobarbital?
Clarithromycin label, drug interactionsOther Drugs Metabolized by CYP3A: Alfentanil Bromocriptine Cilostazol Methylprednisole Vinblastine Phenobarbital St. John’s Wort Use With Caution There have been spontaneous or published reports of CYP3A based interactions of clarithromycin with alfentanil, methylprednisolone, cilostazol, bromocriptine, vinblastine, phenobarbital, and St. John’s Wort.
Source: FDA drug label (Clarithromycin), Solaris Pharma Corporation, effective April 9, 2026 (SPL set 4d42821d-ce7a-7d64-e063-6294a90a0875), via openFDA; the full label on DailyMed
What does the phenobarbital label say about clarithromycin?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name clarithromycin 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
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
| Clarithromycin | Phenobarbital | |
|---|---|---|
| Labeled for | Bacterial infections, Acid reflux and ulcers | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.466 per tablet 500 mg tablet | $0.213 per tablet 100 mg tablet |
| Shortage now | No current entry | 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