What the FDA labels say about taking them together
Doxycycline and pentobarbital
Pentobarbital's FDA label of March 8, 2024 names doxycycline in its drug interactions section; the doxycycline labels PlainMeds reads (4) do not name pentobarbital. The pentobarbital label: “If phenobarbital and doxycycline are administered concurrently, the clinical response to doxycycline should be monitored closely.”
Check it at the source: the doxycycline FDA label on DailyMed (effective July 25, 2025, Chartwell RX, LLC.); the pentobarbital FDA label on DailyMed (effective March 8, 2024, Hikma Pharmaceuticals USA Inc.).
What does the doxycycline label say about pentobarbital?
Doxycycline's label (effective July 25, 2025) and its 3 other brand-application labels do not name pentobarbital in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Doxycycline Monohydrate), Chartwell RX, LLC., effective July 25, 2025 (SPL set 02aa8731-d40f-43d8-8b63-a79a0503f8db), via openFDA; the full label on DailyMed
What does the pentobarbital label say about doxycycline?
Pentobarbital label, drug interactionsIf phenobarbital and doxycycline are administered concurrently, the clinical response to doxycycline should be monitored closely.
Source: FDA drug label (Pentobarbital Sodium), Hikma Pharmaceuticals USA Inc., effective March 8, 2024 (SPL set d375b92a-baa1-4d63-9ad1-1467dcfde7d5), 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
| Doxycycline | Pentobarbital | |
|---|---|---|
| Labeled for | Urinary tract infections, Bacterial infections, Acne | Insomnia |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.118 per tablet 100 mg tablet | n/a |
| Shortage now | A presentation being discontinued | No current entry |
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