Galactorrhea or galactorrhoea is the spontaneous flow of milk from the breast, unassociated with childbirth or nursing. It can be due to dysregulation of certain hormones or local causes such as excessive nipple stimulation.
Lactation requires the presence of estrogen, progesterone and prolactin, and the evaluation of galactorrhea includes eliciting a history for various medications or foods (methyldopa, opiates, some typical antipsychotics, as well as licorice) and for behavioral causes (stress, and breast and chest wall stimulation), as well as evaluation for pregnancy, pituitary adenomas (with overproduction of prolactin or compression of the pituitary stalk), and hypothyroidism. Adenomas of the anterior pituitary are most often prolactinomas. Overproduction of prolactin leads to cessation of menstrual periods and infertility, which may be a diagnostic clue. Galactorrhea may also be caused by hormonal imbalances due to birth control pills.
Contemporary Maternal-Newborn Nursing Care defines glactorrhea as "nipple discharge."
Ladewig, P., London, M., Davidson, M. (2006). Contemporary Maternal-Newborn Nursing Care (6th ed.). New Jersey: Pearson Eduation, Inc.
Galactorrhea is also a side effect associated with the use of the second-generation H2 receptor antagonist Cimetidine (trade name: tagamet).