What the FDA labels say about taking them together
Moxifloxacin and quinidine
Moxifloxacin's FDA label of March 17, 2026 names quinidine in its warnings and precautions section; the quinidine label PlainMeds reads does not name moxifloxacin. The moxifloxacin label: “The drug should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalemia and patients receiving Class IA or Class III antiarrhythmic agents, due to the lack of clinical …”
Check it at the source: the moxifloxacin FDA label on DailyMed (effective March 17, 2026, Macleods Pharmaceuticals Limited); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the moxifloxacin label say about quinidine?
Moxifloxacin label, warnings and precautionsKnown prolongation of the QT interval Ventricular arrhythmias including torsade de pointes because QT prolongation may lead to an increased risk for these conditions Ongoing proarrhythmic conditions, such as clinically significant bradycardia and acute myocardial ischemia, Uncorrected hypokalemia or hypomagnesemia Class IA (for example, quinidine, procainamide) or Class III (for example, amiodarone, sotalol) antiarrhythmic agents Other drugs that prolong the QT interval such as cisapride, erythromycin, antipsychotics, and tricyclic antidepressants Elderly patients using intravenous moxifloxacin may be more susceptible to drug-associated QT prolongation [see Use In Specific Populations ( 8.5 …
Moxifloxacin label (Fresenius Kabi USA, LLC, May 6, 2024), warnings and precautionsThe drug should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalemia and patients receiving Class IA (for example, quinidine, procainamide) or Class III (for example, amiodarone, sotalol) antiarrhythmic agents, due to the lack of clinical experience with the drug in these patient populations.
Source: FDA drug label (Moxifloxacin, NDA205572), Fresenius Kabi USA, LLC, effective May 6, 2024 (SPL set a4e28b09-714b-46e7-b4e6-0163cad78fc5), via openFDA
Source: FDA drug label (Moxifloxacin), Macleods Pharmaceuticals Limited, effective March 17, 2026 (SPL set 182ecd0f-714f-42f0-9b16-fb604cf15786), via openFDA; the full label on DailyMed
What does the quinidine label say about moxifloxacin?
Quinidine's label (effective February 1, 2018) does not name moxifloxacin 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
| Moxifloxacin | Quinidine | |
|---|---|---|
| Labeled for | Bacterial infections | Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $1.60 per mL 0.5% eye drops | $4.92 per tablet 324 mg tablet |
| Shortage now | A presentation being discontinued | 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