👉 Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation in the joints. It affects the body's immune system, leading to excessive production of inflammatory proteins and other substances that cause pain, swelling, and stiffness. RA can affect any part of the body, but it is most common in the hands, knees, hips, and shoulders. The disease typically starts with a gradual onset of pain or inflammation in one area of the joint over several years. Treatment options may include medication