Rheumatoid arthritis (RA) is a condition in which the body's own immune system attacks the joints. This causes swollen, stiff, and painful (inflamed) joints, especially in the hands and feet. Over time, RA can damage and deform joints. It makes it hard to open jars, write, and do other daily tasks. Sometimes it can also cause bumps to form under the skin.
Rheumatoid arthritis is more common in women than in men. It often starts between the ages of 40 and 60. Over time, rheumatoid arthritis can damage and deform joints. Early treatment with medicines may reduce your chances of having a lasting disability.