side effects of relugolix include menstrual abnormalities, hot flashes, excessive sweating, headache, and decreased bone mineral density. relugolix is a gnrh antagonist, or an antagonist of the gonadotropin-releasing hormone receptor. unlike most other gnrh modulators, but similarly to elagolix (brand name orilissa), relugolix is a non-peptide, small-molecule compound and is orally active. it suppresses sex hormone levels to the postmenopausal or castrate range in both women and men with administration once per day.