Excreted into breast milk in quantities that would be clinically significant, however, intestinal absorption by infant's gut is hampered because of formation of chelating products by union with the milk's calcium. No side-effect found among breastfed infants from treated mothers. Plasma levels in those infant were low or undetectable. Long-term treatments (over 3-4 weeks) as for treatment of acne may cause damage to the growth cartilage, teeth discoloration and imbalance of intestinal flora. Thus, a safer alternative should be looked at. (See acne) Be aware of false negative results that may be obtained from infants with bacterial cultures when the mother is on antibiotics. The American Academy of Pediatrics has rated it (2001) as compatible with breastfeeding.