Does Azithromycin Increase Risk for Pyloric Stenosis in Infants?

Oral erythromycin administration to neonates increases their risk for developing infantile hypertrophic pyloric stenosis (IHPS), likely due to the stimulation of gastric motility. Because of this concern, the newer-generation macrolides, azithromycin and clarithromycin, are recommended for infants younger than 1 month of age. Although not commonly prescribed for young infants, macrolides are the antibiotics of choice for the treatment and prophylaxis of pertussis and for the treatment of Chlamydia trachomatis.

To compare the risks for IHPS from exposure to azithromycin versus erythromycin, investigators conducted a retrospective cohort study involving more than 1 million children in the U.S. military health system database who were born betw…