Indomethacin is used to relieve moderate to severe pain, tenderness, swelling, and stiffness caused by osteoarthritis (arthritis caused by a breakdown of the lining of the joints), rheumatoid arthritis (arthritis caused by swelling of the lining of the joints), and ankylosing spondylitis (arthritis that mainly affects the spine). Indomethacin is also used to treat pain in the shoulder caused by bursitis (inflammation of a fluid-filled sac in the shoulder joint) and tendinitis (inflammation of the tissue that connects muscle to bone). Indomethacin immediate-release capsules and suspension (liquid) are also used to treat acute gouty arthritis (attacks of severe joint pain and swelling caused by a build-up of certain substances in the joints). Indomethacin is in a class of medications called NSAIDs. It works by stopping the body's production of a substance that causes pain, fever, and inflammation.