What the FDA labels say about taking them together
Pentobarbital and progesterone
Pentobarbital's FDA label of March 8, 2024 names progesterone in its drug interactions section; the progesterone labels PlainMeds reads (3) do not name pentobarbital. The pentobarbital label: “Estradiol, estrone, progesterone and other steroidal hormones: Pretreatment with or concurrent administration of phenobarbital may decrease the effect of estradiol by increasing its metabolism.”
Check it at the source: the pentobarbital FDA label on DailyMed (effective March 8, 2024, Hikma Pharmaceuticals USA Inc.); the progesterone FDA label on DailyMed (effective July 23, 2026, Acertis Pharmaceuticals, LLC).
What does the pentobarbital label say about progesterone?
Pentobarbital label, drug interactionsEstradiol, estrone, progesterone and other steroidal hormones: Pretreatment with or concurrent administration of phenobarbital may decrease the effect of estradiol by increasing its metabolism.
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
What does the progesterone label say about pentobarbital?
Progesterone's label (effective July 23, 2026) and its 2 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 (Prometrium), Acertis Pharmaceuticals, LLC, effective July 23, 2026 (SPL set 1cf237ff-c4f8-4faa-a7aa-77599c856889), 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
| Pentobarbital | Progesterone | |
|---|---|---|
| Labeled for | Insomnia | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.229 per capsule 100 mg capsule |
| 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