Pregnancy Available data from published literature and postmarketing experience over several decades with azithromycin use in pregnant women have not identified drug-associated risks for major birth defects, miscarriage, or adverse maternal or fetal outcomes (see Data); data do not suggest embryofetal risk (Developmental and Reproductive Toxicology Database [DART]; https://toxnet.nlm.nih.gov/newtoxnet/dart.htm) Animal data Developmental toxicity studies with azithromycin in rats, mice, and rabbits showed no drug-induced fetal malformations at doses up to 4, 2, and 2 times, respectively, an adult human daily dose of 500 mg based on body surface area; decreased viability and delayed development were observed in offspring of pregnant rats administered azithromycin from day 6 of pregnancy through weaning at a dose equivalent to 4 times an adult human daily dose of 500 mg based on body surface area Lactation Drug is present in human milk; non-serious adverse reactions reported in breastfed infants after maternal administration of therapy; there are no available data on effects on milk production; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and potential adverse effects on breastfed infant from drug or underlying maternal condition; advise women to monitor breastfed infant for diarrhea, vomiting, or rash.