Indomethacin is used to relieve pain, swelling, and joint stiffness caused by arthritis, gout, bursitis, and tendonitis. It is also used to relieve pain from various other conditions. This medication is known as a nonsteroidal anti-inflammatory drug (NSAID). It works by blocking your body's production of certain natural substances that cause inflammation. This effect helps to decrease swelling and pain. If you are treating a chronic condition such as arthritis, ask your doctor about non-drug treatments and/or using other medications to treat your pain. See also Warning section.