What the FDA labels say about taking them together
Propranolol and theophylline
Propranolol's FDA label of January 15, 2026 names theophylline in its drug interactions section, and theophylline's label names propranolol too. The theophylline label: “Beta-2 blocking effect may decrease efficacy of theophylline. Propranolol Similar to cimetidine and pharmacologic interaction.”
Check it at the source: the propranolol FDA label on DailyMed (effective January 15, 2026, Mylan Pharmaceuticals Inc.); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the propranolol label say about theophylline?
Propranolol label, drug interactionsSubstrates or Inhibitors of CYP1A2 Blood levels and/or toxicity of propranolol may be increased by co-administration with substrates or inhibitors of CYP1A2, such as imipramine, cimetidine, ciprofloxacin, fluvoxamine, isoniazid, ritonavir, theophylline, zileuton, zolmitriptan, and rizatriptan.
Source: FDA drug label (Propranolol Hydrochloride), Mylan Pharmaceuticals Inc., effective January 15, 2026 (SPL set b94dcec7-7633-4a33-9cea-48161adeaf93), via openFDA; the full label on DailyMed
What does the theophylline label say about propranolol?
Theophylline label, drug interactionsBeta-2 blocking effect may decrease efficacy of theophylline. Propranolol Similar to cimetidine 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
| Propranolol | Theophylline | |
|---|---|---|
| Labeled for | High blood pressure, Angina, Atrial fibrillation, Migraine | Asthma |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0493 per tablet 20 mg tablet | $0.330 per tablet 300 mg tablet |
| Shortage now | In shortage | 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