What the FDA labels say about taking them together
Isoproterenol and theophylline
Theophylline's FDA label of March 10, 2026 names isoproterenol in its drug interactions section; the isoproterenol label PlainMeds reads does not name theophylline. The theophylline label: “100% increase Isoproterenol (IV) Increases theophylline clearance.”
Check it at the source: the isoproterenol FDA label on DailyMed (effective December 16, 2025, Eugia US LLC); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the isoproterenol label say about theophylline?
Isoproterenol's label (effective December 16, 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 (Isoproterenol Hydrochloride), Eugia US LLC, effective December 16, 2025 (SPL set 3e4050e8-7d94-4ed7-951d-1ff818ddadf1), via openFDA; the full label on DailyMed
What does the theophylline label say about isoproterenol?
Theophylline label, drug interactions100% increase Isoproterenol (IV) Increases theophylline clearance.
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
| Isoproterenol | Theophylline | |
|---|---|---|
| Labeled for | n/a | Asthma |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $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