What is Increlex? Increlex (https://goodmanpharmaceuticals.org/product/increlex-mecasermin/) is a man-made form of insulin-like growth factor-1 (IGF-1), a substance that is normally produced in the body. IGF-1 is important for the growth of bones and muscles. Increlex is used to treat growth failure in children whose bodies do not make enough IGF-1.