What the FDA labels say about taking them together
Mexiletine and quinidine
Mexiletine's FDA label of May 14, 2026 names quinidine in its drug interactions section, and quinidine's label names mexiletine too.
Check it at the source: the mexiletine FDA label on DailyMed (effective May 14, 2026, Macleods Pharmaceuticals Limited); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the mexiletine label say about quinidine?
Mexiletine label, drug interactionsA variety of antiarrhythmics such as quinidine or propranolol were also added, sometimes with improved control of ventricular ectopy.
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 quinidine label say about mexiletine?
Quinidine label, drug interactionsCytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine, some phenothiazines, and most polycyclic antidepressants.
Source: FDA drug label (Quinidine Gluconate), Sun Pharmaceutical Industries, Inc., effective February 1, 2018 (SPL set 5023f053-fcc4-4c2c-aa59-9ec198ad185e), 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 | Quinidine | |
|---|---|---|
| Labeled for | n/a | Atrial fibrillation |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.222 per capsule 150 mg capsule | $4.92 per tablet 324 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