What the FDA labels say about taking them together
Ciprofloxacin and quinidine
Ciprofloxacin's FDA label of March 2, 2026 names quinidine in its warnings and precautions section, and quinidine's label names ciprofloxacin too. The ciprofloxacin label: “… torsade de pointes, and patients receiving Class IA antiarrhythmic agents (quinidine, procainamide), or Class III antiarrhythmic agents (amiodarone, sotalol), tricyclic antidepressants, macrolides, and antipsychotics.”
Check it at the source: the ciprofloxacin FDA label on DailyMed (effective March 2, 2026, Bayer HealthCare Pharmaceuticals Inc.); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the ciprofloxacin label say about quinidine?
Ciprofloxacin label, warnings and precautionsAvoid CIPRO in patients with known prolongation of the QT interval, risk factors for QT prolongation or torsade de pointes (for example, congenital long QT syndrome, uncorrected electrolyte imbalance, such as hypokalemia or hypomagnesemia and cardiac disease, such as heart failure, myocardial infarction, or bradycardia), and patients receiving Class IA antiarrhythmic agents (quinidine, procainamide), or Class III antiarrhythmic agents (amiodarone, sotalol), tricyclic antidepressants, macrolides, and antipsychotics.
Source: FDA drug label (Cipro), Bayer HealthCare Pharmaceuticals Inc., effective March 2, 2026 (SPL set 888dc7f9-ad9c-4c00-8d50-8ddfd9bd27c0), via openFDA; the full label on DailyMed
What does the quinidine label say about ciprofloxacin?
Quinidine label, drug interactionsConversely, the pharmacokinetics of quinidine are not significantly affected by caffeine, ciprofloxacin, digoxin, felodipine, omeprazole, or quinine.
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
| Ciprofloxacin | Quinidine | |
|---|---|---|
| Labeled for | Diarrhea, Urinary tract infections, Bacterial infections | Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.123 per tablet 500 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