What the FDA labels say about taking them together
Erythromycin and procainamide
Erythromycin's FDA label of August 1, 2024 names procainamide in its warnings section; the procainamide label PlainMeds reads does not name erythromycin. The erythromycin label: “… clinically significant bradycardia, and in patients receiving Class IA (quinidine, procainamide) or Class III antiarrhythmic agents.”
Check it at the source: the erythromycin FDA label on DailyMed (effective August 1, 2024, Teva Pharmaceuticals USA, Inc.); the procainamide FDA label on DailyMed (effective February 17, 2025, Caplin Steriles Limited).
What does the erythromycin label say about procainamide?
Erythromycin label, warningsErythromycin should be avoided in patients with known prolongation of the QT interval, patients with ongoing proarrhythmic conditions such as uncorrected hypokalemia or hypomagnesemia, clinically significant bradycardia, and in patients receiving Class IA (quinidine, procainamide) or Class III (dofetilide, amiodarone, sotalol) antiarrhythmic agents.
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 procainamide label say about erythromycin?
Procainamide's label (effective February 17, 2025) does not name erythromycin in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Procainamide Hydrochloride), Caplin Steriles Limited, effective February 17, 2025 (SPL set fcaa5e9a-3c8a-4796-aa87-626268b6cf60), 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 | Procainamide | |
|---|---|---|
| Labeled for | Bacterial infections, Acne | n/a |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $1.96 per tablet 250 mg tablet | n/a |
| 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