First-generation cephalosporin. Oral administration. Like most cephalosporins for which data are available, excretion occurs in breast milk in very small amount and it is clinically insignificant (Kafetzis 1981, Matsuda 1984, Ilett 2006). Cephalosporins are widely used in the Pediatric practice with a good tolerance, even in the neonatal period, so it is very unlikely that in small amounts through milk would be a cause of problems in the infant. Be aware of the possibility of false negative results of cultures in febrile infants whose mothers are taking antibiotics as well as the possibility of gastroenteritis (Ito 1993) by altering the intestinal flora. Cephalexin is not excreted in significant amount into breast milk (Kafetzis 1981, Matsuda 1984, Ilett 2006). Be aware of false negative bacterial cultures in the infant when the mother is on antibiotics. Also, diarrheal disease due to imbalance of intestinal flora is possible (Ito 1993, Benyamini 2005). A case of a mother reportedly treated with Cephalexine and Probenecid occurred (Ilett 2006).