What Is Tesamorelin? Tesamorelin is a synthetic Growth Hormone-Releasing Hormone (GHRH) analogue. It works by stimulating the pituitary gland to produce and release more of your body’s natural growth hormone (GH), which then increases levels of Insulin-Like Growth Factor 1 (IGF-1). Unlike synthetic growth hormone, Tesamorelin does not replace GH—it encourages your body to produce