What the FDA labels say about taking them together
Dolutegravir and phenobarbital
Dolutegravir's FDA label of May 22, 2026 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name dolutegravir. The dolutegravir label: “Avoid coadministration with TIVICAY or TIVICAY PD because there are insufficient data to make dosing recommendations.”
Check it at the source: the dolutegravir FDA label on DailyMed (effective May 22, 2026, ST. MARY'S MEDICAL PARK PHARMACY); the phenobarbital FDA label on DailyMed (effective August 27, 2026).
What does the dolutegravir label say about phenobarbital?
Dolutegravir label, drug interactionsConcomitant Drug Class/Drug Name: Oxcarbazepine Phenytoin Phenobarbital St. John’s wort ( Hypericum perforatum); Effect on Concentration of Dolutegravir and/or Concomitant Drug: ↓Dolutegravir; Clinical Comment: Avoid coadministration with TIVICAY or TIVICAY PD because there are insufficient data to make dosing recommendations.
Source: FDA drug label (Tivicay), NDA204790 (Viiv Hlthcare), as published by ST. MARY'S MEDICAL PARK PHARMACY, effective May 22, 2026 (SPL set 485bc9db-8665-9f5a-e063-6394a90a7921), via openFDA; the full label on DailyMed
What does the phenobarbital label say about dolutegravir?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name dolutegravir 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
| Dolutegravir | Phenobarbital | |
|---|---|---|
| Labeled for | HIV | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $77.64 per tablet 50 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