Gonadotropin-releasing hormone antagonists reduce the levels of estrogen and testosterone in the body. They're used to treat hormone-sensitive health conditions such as prostate cancer and endometriosis. They also prevent mature eggs from being released early during fertility treatment. Some of these medications are taken orally, while others are injectioned. Examples include ganirelix (Fyremadel), elagolix (Orilissa), and relugolix (Orgovyx).