What the FDA labels say about taking them together
Levofloxacin and quinidine
Levofloxacin's FDA label of July 10, 2024 names quinidine in its warnings and precautions section; the quinidine label PlainMeds reads does not name levofloxacin. The levofloxacin label: “Levofloxacin should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalemia, and patients receiving Class IA (quinidine, procainamide), or Class III (amiodarone, sotalol) …”
Check it at the source: the levofloxacin FDA label on DailyMed (effective July 10, 2024, Lupin Pharmaceuticals, Inc.); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the levofloxacin label say about quinidine?
Levofloxacin label, warnings and precautionsLevofloxacin should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalemia, and patients receiving Class IA (quinidine, procainamide), or Class III (amiodarone, sotalol) antiarrhythmic agents.
Source: FDA drug label (Levofloxacin), Lupin Pharmaceuticals, Inc., effective July 10, 2024 (SPL set 4be13bd5-0c39-43c3-9232-b1226ccd4dbc), via openFDA; the full label on DailyMed
What does the quinidine label say about levofloxacin?
Quinidine's label (effective February 1, 2018) does not name levofloxacin 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
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
| Levofloxacin | Quinidine | |
|---|---|---|
| Labeled for | Bacterial infections, Urinary tract infections | Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.259 per tablet 750 mg tablet | $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