Prolactin inhibitors 

Prolactin inhibitors are agents that inhibit the production of prolactin, a hormone that stimulates milk production after childbirth. In both sexes, excessive secretion of prolactin (hyperprolactinemia) can give rise to abnormal production of milk (galactorrhea).

Prolactin inhibitors are dopamine agonists, which effectively treat hyperprolactinemia.

D₂ receptor agonists that are described as prolactin inhibitors include the approved medications bromocriptine, cabergoline, lisuride, metergoline, pergolide, quinagolide, and terguride and the never-marketed agent lergotrile.

Notably, dopamine suppresses prolactin production and release, which is dissimilar to other anterior pituitary hormones that exhibit stimulated release by hypothalamic regulatory hormones. Because of this inhibitory effect on prolactin release, dopamine may also be referred to as PRIH.