Rheumatoid arthritis (RA) is an autoimmune disease in which the body’s immune system – which normally protects its health by attacking foreign substances like bacteria and viruses – mistakenly attacks the joints.
This creates inflammation that causes the tissue that lines the inside of joints (the synovium) to thicken, resulting in swelling and pain in and around the joints.
The symptoms and effects of RA may come and go. A period of high disease activity (increases in inflammation and other symptoms) is called a flare. A flare can last for days or months.
Ongoing high levels of inflammation can cause problems throughout the body. Here of some ways RA can affect organs and body systems: