The exact cause of rheumatoid arthritis is unknown. However, it is believed to be caused by a combination of genetic factors, abnormal immunity, environmental factors, and hormonal factors.

Normally, the immune system protects the body from disease. In rheumatoid arthritis, something triggers the immune system to attack the joints and sometimes other organs. Some theories suggest that a virus or bacteria may alter the immune system, causing it to attack the joints. Some people have a genetic or inherited factor that makes them more likely to develop rheumatoid arthritis.

Learn more about the causes of rheumatoid arthritis.

Abundant evidence suggests that rheumatoid arthritis (RA) is an autoimmune reaction, in which antibodies formed by the immune system attack components of joint tissues. Yet what triggers this autoimmune reaction remains largely unknown. Speculation and investigation have centered around genetic factors, abnormal bowel permeability, lifestyle and nutritional factors, food allergies, impaired liver detoxification, and microorganisms. RA is a classic example of a multifactorial disease, wherein an assortment of genetic and environmental factors contributes to the disease process.