What the FDA labels say about taking them together
Aminophylline and phenobarbital
Aminophylline's FDA label of May 22, 2026 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name aminophylline. The aminophylline label: “30% increase Phenobarbital (PB) Similar to aminoglutethimide.”
Check it at the source: the aminophylline FDA label on DailyMed (effective May 22, 2026, Hospira, Inc.); the phenobarbital FDA label on DailyMed (effective August 27, 2026).
What does the aminophylline label say about phenobarbital?
Aminophylline label, drug interactions30% increase Phenobarbital (PB) Similar to aminoglutethimide.
Source: FDA drug label (Aminophylline), Hospira, Inc., effective May 22, 2026 (SPL set 9a663ef3-881f-48bd-2689-3713b24545c2), via openFDA; the full label on DailyMed
What does the phenobarbital label say about aminophylline?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name aminophylline 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
| Aminophylline | Phenobarbital | |
|---|---|---|
| Labeled for | Asthma | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $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