Melanotan-2 (MT-2) is a lab-made version of a hormone called alpha-melanocyte-stimulating hormone. Created in the 1980s, it has been found to have several effects, such as boosting sexual desire, reducing addictive behaviors, decreasing hunger, and increasing melanin, the pigment that darkens the skin. Studies suggest that it stimulates skin cells called melanocytes, which help darken the skin, and it may also support early childhood development in autism.