Prolactin is a hormone produced by the pituitary gland, the main purpose of which is to help women produce milk following childbirth, although it is an important hormone for both male and female reproductive health.

High levels of prolactin (or hyperprolactinemia) are normal after childbirth. Too much prolactin may be a sign of an underlying medical condition, such as kidney disease, hyperthyroidism or liver disease. 

Symptoms of high prolactin levels in women include infertility, mood changes, irregular menstruation in women, and discharge from the breasts. In men, too much prolactin may lead to a decrease in libido and erectile dysfunction. 

Vitamin B-6 and E supplements may help lower prolactin levels, as can dietary changes and certain prescription medicines, such as prolactin inhibitors.