Less than 0.05% of the maternal dose of roxithromycin is excreted in milk (AEMPS 2002, Puri 1987). Early exposure to macrolides (especially erythromycin, see specific information) has been linked to the occurrence of hypertrophic pyloric stenosis (Goldstein 2009, Chin 2001), including through breast milk, so it may be prudent to avoid them during the first month of breastfeeding. Be aware of false negative results of bacterial cultures obtained from febrile infants whose mothers are on antibiotics, as well as the possibility of gastroenteritis due to altered intestinal flora (Ito 1993).