What the FDA labels say about taking them together
Dapsone and phenobarbital
Dapsone's FDA label (Aczone) of October 23, 2025 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name dapsone. The dapsone label: “… nitroglycerin, nitroprusside, pamaquine, para‐aminosalicylic acid, phenacetin, phenobarbital, phenytoin, primaquine, and quinine may increase the risk for developing methemoglobinemia.”
Check it at the source: the dapsone FDA label on DailyMed (effective July 20, 2026, Macleods Pharmaceuticals Limited); the phenobarbital FDA label on DailyMed (effective August 27, 2026).
What does the dapsone label say about phenobarbital?
Aczone label (Almirall, LLC, October 23, 2025), drug interactionsUse with Drugs that Induce Methemoglobinemia Concomitant use of ACZONE Gel, 7.5% with drugs that induce methemoglobinemia such as sulfonamides, acetaminophen, acetanilide, aniline dyes, benzocaine, chloroquine, dapsone, naphthalene, nitrates and nitrites, nitrofurantoin, nitroglycerin, nitroprusside, pamaquine, para‐aminosalicylic acid, phenacetin, phenobarbital, phenytoin, primaquine, and quinine may increase the risk for developing methemoglobinemia [see Warnings and Precautions ( 5.1 )].
Source: FDA drug label (Aczone, NDA207154), Almirall, LLC, effective October 23, 2025 (SPL set 22058b7d-a578-4eaa-a476-ac982337f02a), via openFDA
Source: FDA drug label (Dapsone, NDA021794), Pacific Pharma, Inc., effective September 30, 2018 (SPL set 8dbe1a41-6d9d-414f-aa9c-09bd95857e2a), via openFDA
Source: FDA drug label (Dapsone), Macleods Pharmaceuticals Limited, effective July 20, 2026 (SPL set 839d7440-ba0e-4c56-b648-d374b155cf03), via openFDA; the full label on DailyMed
What does the phenobarbital label say about dapsone?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name dapsone 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
| Dapsone | Phenobarbital | |
|---|---|---|
| Labeled for | Acne | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.664 per gram 5% gel | $0.213 per tablet 100 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