What the FDA labels say about taking them together
Mexiletine and theophylline
Mexiletine's FDA label of May 14, 2026 names theophylline in its drug interactions section, and theophylline's label names mexiletine too. The mexiletine label: “Concurrent use of mexiletine and theophylline may lead to increased plasma theophylline levels.”
Check it at the source: the mexiletine FDA label on DailyMed (effective May 14, 2026, Macleods Pharmaceuticals Limited); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the mexiletine label say about theophylline?
Mexiletine label, drug interactionsConcurrent use of mexiletine and theophylline may lead to increased plasma theophylline levels.
Source: FDA drug label (Mexiletine Hydrochloride), Macleods Pharmaceuticals Limited, effective May 14, 2026 (SPL set a61a07f6-0b48-4dcd-ad42-5d90f6e69ab1), via openFDA; the full label on DailyMed
What does the theophylline label say about mexiletine?
Theophylline label, drug interactionsMexiletine Similar to disulfiram.
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
| Mexiletine | Theophylline | |
|---|---|---|
| Labeled for | n/a | Asthma |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.222 per capsule 150 mg capsule | $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