Risperdal causes highly elevated prolactin levels, even at recommended low doses. Prolactin is a hormone that is normally present in the body. It plays an essential role in metaobolism and regulation of the immune system. Prolactin regulates lactation in the human body, and during pregnancy, causes an enlargement of the mammary glands of the breasts in order to prepare for the production of milk.
While prolactin also naturally occurs in men, it is typically present at much lower levels than in women. Elevated prolactin levels in human body induce breast growth and lactiation. When prolactin is elevated in men and boys, the result can be the growth of female breasts.
Many antipyschotics cause weight gain. But gynecomastia is not simple weight gain – it is the actual growth of female breast gland tissue. Risperdal and Invega cause an increase in prolactin levels in men and boys, much more so than other antipsychotics. Even after you stop taking these drugs, high levels of this breast growth hormone can persist for up to two years. In fact, 20% of the time, when female breast growth occurs in men, this effect is due to taking drugs of some kind.