Like most penicillin-type antibiotics, excretion into breast milk is clinically non-significant. No harmful effects have been found among breastfed infants from treated mothers. Widely used for treatment of Mastitis since it has an effective activity against Staphylococcus. Be aware of false negative results of microbial cultures done from samples of febrile infants whose mothers are treated with antibiotics. Also, due to imbalance of intestinal flora a diarrheal disease can occur in the breastfed infant. List of Essential Medicines by WHO 2002: compatible with breastfeeding.