What the FDA labels say about taking them together
Propafenone and theophylline
Theophylline's FDA label of March 10, 2026 names propafenone in its drug interactions section; the propafenone label PlainMeds reads does not name theophylline. The theophylline label: “Serum theophylline and phenytoin concentrations decrease about 40%. Propafenone Decreases theophylline clearance and pharmacologic interaction.”
Check it at the source: the propafenone FDA label on DailyMed (effective September 1, 2025, Strides Pharma Science Limited); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the propafenone label say about theophylline?
Propafenone's label (effective September 1, 2025) does not name theophylline in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (PROPAFENONE HYDROCHLORIDE), Strides Pharma Science Limited, effective September 1, 2025 (SPL set c65253ab-937f-4982-b841-69c2b9f9ccdb), via openFDA; the full label on DailyMed
What does the theophylline label say about propafenone?
Theophylline label, drug interactionsSerum theophylline and phenytoin concentrations decrease about 40%. Propafenone Decreases theophylline clearance and pharmacologic interaction.
Source: FDA drug label (Theophylline), Strides Pharma Science Limited, effective March 10, 2026 (SPL set b7a90ccf-9c32-40cc-9008-7e55b3da4dfd), 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
| Propafenone | Theophylline | |
|---|---|---|
| Labeled for | Atrial fibrillation | Asthma |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.115 per tablet 150 mg tablet | $0.330 per tablet 300 mg tablet |
| Shortage now | No current entry | 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