Erythromycin is a macrolide antibiotic used as a prokinetic in dogs and cats. It is most often used as a second-line promotility agent to aid in gastric emptying in conjunction with metoclopramide, but it may be used alone. Care should be taken to avoid drug-drug interactions via the cytochrome P450 enzyme system.

Mechanism of Action/Pharmacokinetics

  • Erythromycin’s promotility effects are not completely understood, but, at low doses, it is suspected to be due to binding to motilin and serotonin (5-HT3) receptors. Once bound, it stimulates contractions in the stomach and intestines by activating the migrating motility complexes and antegrade peristalsis.
  • Erythromycin also increases lower esophageal pressure. Additionally, erythromycin is reported to stimulate colonic activity in dogs.
  • Combination therapy with metoclopramide has been shown to be more efficacious than therapy with either agent alone.


  • Gastroparesis
  • Reflux esophagitis
  • Constipation (dogs)

Dosing suggestions/guidelines

  • 0.5 – 1.0 mg/kg IV/PO q 8

Dosage forms

  • Injectable: Erythromycin lactobionate 500mg/10mL vial
  • Oral: Erythromycin ethylsuccinate tablets 400mg at a commercial pharmacy
    • Erythromycin suspension can be compounded

Adverse effects

  • Vomiting after oral administration
  • Diarrhea in dogs
  • A case of a dog with the MDR1 mutation developing neurologic signs was reported. This may not be a concern at the lower dosage.

Drug/Drug interaction

  • Possible reduction in cisapride metabolism
  • Contraindicated: chloramphenicol, clindamycin/lincomycin, digoxin, warfarin
  • Increase or decrease levels via P450 enzyme system: alfentanil, bromocriptine, buspirone, carbamazepine, cyclosporine, disopyramide, methylprednisone, midazolam, alprazolam, sildenafil, quinidine, tacrolimus, theophylline


  • Nguyen NQ, Chapman MJ, Fraser RJ, Bryant LK, Holloway RH. Erythromycin is more effective than metoclopramide in the treatment of feed intolerance in critical illness. Crit Care Med. 2007;35(2):483-9. Download article
  • Nguyen NQ, Chapman M, Fraser R et al. Prokinetic therapy for feed intolerance in critical illness: one drug or two? Crit Care Med 2007;35:2561-7. Download article
  • MacLaren R, Kiser TH, Fish DN, Wischmeyer PE. Erythromycin vs metoclopramide for facilitating gastric emptying and tolerance to intragastric nutrition in critically ill patients. JPEN Journal of parenteral and enteral nutrition 2008;32(4):412-9. Download article
  • Sato F, Marui S, Inatomi N, et al. EM574, an erythromycin derivative, improves delayed gastric emptying of semi-solid meals in conscious dogs. Eur J Pharmacol 2000;395:165–72. Download article

Additional resources

Last updated: 2018-03-28