Etrasimod is primarily used in the treatment of autoimmune diseases, particularly those involving inflammation. It is effective in managing conditions like ulcerative colitis, a chronic inflammatory bowel disease, by modulating the immune response and reducing inflammation in the gastrointestinal tract. Additionally, it shows promise in treating other autoimmune disorders such as Crohn's disease and multiple sclerosis, where it helps to control the overactive immune system. By targeting specific receptors involved in immune cell migration, Etrasimod helps to prevent immune cells from reaching sites of inflammation, thereby alleviating symptoms and improving patient outcomes. Its oral administration offers a convenient treatment option for patients, enhancing adherence to therapy.