Megestrol acetate is a synthetic progestin used primarily in cancer treatment, particularly for breast and endometrial cancer. Additionally, it is prescribed to stimulate appetite and promote weight gain in conditions such as cancer-associated anorexia, HIV/AIDS-related wasting syndrome, and other situations involving significant weight loss. The medication has progestin activity and is available in forms like tablets and oral suspension. Side effects may include weight gain, fluid retention, and changes in appetite.