Limited information indicates that maternal doses of nalidixic acid up to 2 grams daily produce low levels in milk and would usually not be expected to cause any adverse effects in breastfed infants with monitoring of the infant for possible effects on the gastrointestinal flora, such as diarrhea or candidiasis (thrush, diaper rash). Nalidixic acid should be avoided while breastfeeding a glucose-6-phosphate dehydrogenase (G6PD) deficient infant. Other agents are preferred, especially while nursing a newborn or preterm infant.