What the FDA labels say about taking them together
Quinidine and tolterodine
Tolterodine's FDA label of February 9, 2026 names quinidine in its warnings and precautions section; the quinidine label PlainMeds reads does not name tolterodine. The tolterodine label: “Advise patients not to drive or operate heavy machinery until they know how tolterodine tartrate extended-release capsules affect them. Myasthenia Gravis: use caution in patients with myasthenia gravis. …”
Check it at the source: the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.); the tolterodine FDA label on DailyMed (effective February 9, 2026, Torrent Pharmaceuticals Limited).
What does the quinidine label say about tolterodine?
Quinidine's label (effective February 1, 2018) does not name tolterodine in these sections. A label lists what its studies and reports found; it is not a complete list.
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
What does the tolterodine label say about quinidine?
Tolterodine label, warnings and precautionsAdvise patients not to drive or operate heavy machinery until they know how tolterodine tartrate extended-release capsules affect them. ( 5.5 ) Myasthenia Gravis: use caution in patients with myasthenia gravis. ( 5.8 ) QT Prolongation: consider observations from the thorough QT study in clinical decisions to prescribe tolterodine tartrate extended-release capsules to patients with a known history of QT prolongation or to patients who are taking Class IA (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmic medications.
Source: FDA drug label (TOLTERODINE TARTRATE), Torrent Pharmaceuticals Limited, effective February 9, 2026 (SPL set db6e0b6d-0ce5-41d7-881f-881c11f530a4), 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
| Quinidine | Tolterodine | |
|---|---|---|
| Labeled for | Atrial fibrillation | Overactive bladder |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $4.92 per tablet 324 mg tablet | $0.268 per capsule 2 mg capsule |
| 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