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 for alopecia areata, helping regrow hair by targeting the immune attack on hair follicles. Has been studied for use in COVID-19 to reduce inflammation in severe cases, particularly when combined with antiviral drugs. Taken orally as a tablet, it helps improve physical function and reduce symptoms like pain and swelling.