Excreted into breast milk in a non-significant clinical amount. Not problems on breastfed infants of treated mothers were found. Plasma levels were low or undetectable in those infants. For a mother's dose of 400 mg three times-a-day, the intake of a breastfed infant would be less than 10% of the usual daily pediatric dose, whenever the breast-feed is done within 2-3 hours of mother's intake. Widely used for treatment of Giardia lamblia infections, even in small infants, without adverse effects reported. Metronidazole may produce a red discoloration of corporal fluids and bitter flavor of the milk with no harm effect on the child.