Prolactin is the hormone that tells the cells in the breast to make milk when a woman is breastfeeding. The brain is home to the gland that makes prolactin.

During pregnancy and breastfeeding, the body makes more of the hormone prolactin.

In abnormal conditions, an excessive rise in the prolactin hormone causes the following signs and symptoms:
• Milk secretion from breasts
• Absence of menstrual flow
• Decreased menstrual flow
• Headache or blurring of vision coupled with above-mentioned symptoms.

Pathological increases can be caused by hypothyroidism, polycystic ovaries, drugs, or a prolactin-secreting tumor.