Used to treat moderate to severe rheumatoid arthritis in adults who have not responded well to other treatments. It works by reducing inflammation and slowing joint damage. Also used in some cases of alopecia areata, helping regrow hair by targeting the immune attack on hair follicles. Has been explored for use in severe cases of autoimmune-related conditions, including during certain viral infections where immune overreaction is a concern. Taken orally, it offers a convenient option compared to injectable therapies.