Tesamorelin injection is used to decrease the amount of extra fat in the stomach area in adults with human immunodeficiency virus (HIV) who have lipodystrophy (increased body fat in certain areas of the body). Tesamorelin injection is not used to help with weight loss. Tesamorelin injection is in a class of medications called human growth hormone-releasing factor (GRF) analogs. It works by increasing the production of a certain natural substance that can decrease the amount of body fat.