Since the first publication of this statement, much new information has been published concerning the transfer of drugs and chemicals into human milk. This information, in addition to other research published before 1983, makes a revision of the previous statement necessary. In this revision, lists of the pharmacologic or chemical agents transferred into human milk and their possible effects on the infant or on lactation, if known, are provided (Tables 1 to 7). The fact that a pharmacologic or chemical agent does not appear in the Tables is not meant to imply that it is not transferred into human milk or that it does not have an effect on the infant but indicates that there are no reports in the literature. These tables should assist the physician in counseling a nursing mother regarding breast-feeding when the mother has a condition for which a drug is medically indicated.
The following questions should be considered when prescribing drug therapy to lactating women. (1) Is the drug therapy really necessary? Consultation between the pediatrician and the mother's physician can be most useful. (2) Use the safest drug; for example, acetaminophen rather than aspirin for oral analgesia. (3) If there is a possibility that a drug may present a risk to the infant (eg, phenytoin, phenobarbital), consideration should be given to measurement of blood concentrations in the nursing infant. (4) Drug exposure to the nursing infant may be minimized by having the mother take the medication just after completing a breast-feeding and/or just before the infant has his or her lengthy sleep periods.