Which macrolide is typically avoided in infants under 1 year due to a specific risk?

Erythromycin is generally avoided in infants under 1 year due to the risk of developing a condition called hypertrophic pyloric stenosis. This condition, characterized by the narrowing of the pylorus leading to gastric outlet obstruction, has been associated with the use of erythromycin in this age group, particularly when administered in the first few months of life. The risk appears to be particularly significant in infants younger than 2 months.

In contrast, azithromycin and clarithromycin are typically considered safer alternatives in pediatric patients and have not been associated with the same risk of hypertrophic pyloric stenosis. Spiramycin is also not commonly used in this context and does not carry the same concerns as erythromycin. Thus, the specific risks associated with erythromycin make it the macrolide that is typically avoided in infants under 1 year.