Drugs affecting lactation.

The effects of a variety of drugs on lactation are described. Drugs affect lactation either by modifying breast tissue or by influencing prolactin secretion. Androgens and progesterones stimulate the growth of breast tissue, and estrogens, which are frequently used to suppress lactation, stimulate breast duct growth. Many psychotropic drugs increase prolactin levels and cause galactorrhea while other centrally acting drugs inhibit lactation. The names and the mechanism of action of all centrally acting drugs which cause galactorrhea and of all those known to inhibit lactation are provided in tabular form. Suggestions related to the clinical use of the sex steroids and the centrally acting drugs are 1) the use of estrogens to suppress lactation should be limited to the shortest possible time; 2) if galactorrhea occurs in a menopausal patient who is taking oral contraceptives or estrogens, she should be examined for pituitary tumor; 3) if galactorrhea occurs in a patient who is taking a centrally acting drug known to cause galactorrhea, the patient need not be examined for pituitary tumor unless other symptoms are present; 4) the use of centrally acting drugs by women predisposed to breast cancer should be avoided; 5) nursing mothers should avoid taking large doses of barbiturates and pyridoxine as these drugs may reduce lactation; and 6) the use of bromocryptine to suppress postpartum lactation may stimulate early ovulation, and patients should be warned about the need to use contraceptives.