The nursing infant, not being a miniature adult, has physiologic differences that need to be considered when he or she is subjected to drugs through breastfeeding. These differences may include an immature liver, decreased albumen levels, and an inability to excrete agents in the urine and stool. Besides immediate pharmacologic effects, possible long-term complications of each drug need to be considered. As can be seen from the data, many drugs that are prescribed by the dental profession are not considered hazardous to the nursing infant. However, this generalization is not appropriate for individual patients, and the prescribing dentist is advised to administer systemic drugs to lactating mothers with discretion and close follow-up.