What the FDA labels say about taking them together
Erythromycin and moxifloxacin
Moxifloxacin's FDA label of March 17, 2026 names erythromycin in its warnings and precautions section; the erythromycin labels PlainMeds reads (4) do not name moxifloxacin. The moxifloxacin label: “Pharmacokinetic studies between moxifloxacin and other drugs that prolong the QT interval such as cisapride, erythromycin, antipsychotics, and tricyclic antidepressants have not been performed.”
Check it at the source: the erythromycin FDA label on DailyMed (effective August 1, 2024, Teva Pharmaceuticals USA, Inc.); the moxifloxacin FDA label on DailyMed (effective March 17, 2026, Macleods Pharmaceuticals Limited).
What does the erythromycin label say about moxifloxacin?
Erythromycin's label (effective August 1, 2024) and its 3 other brand-application labels do 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 (Erythromycin), Teva Pharmaceuticals USA, Inc., effective August 1, 2024 (SPL set 75a0bd5a-d09f-483b-bfd8-f8343b149eb2), via openFDA; the full label on DailyMed
What does the moxifloxacin label say about erythromycin?
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 precautionsPharmacokinetic studies between moxifloxacin and other drugs that prolong the QT interval such as cisapride, erythromycin, antipsychotics, and tricyclic antidepressants have not been performed.
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
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
| Erythromycin | Moxifloxacin | |
|---|---|---|
| Labeled for | Bacterial infections, Acne | Bacterial infections |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $1.96 per tablet 250 mg tablet | $1.60 per mL 0.5% eye drops |
| Shortage now | No current entry | A presentation being discontinued |
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