Rheumatoid arthritis (RA) is a serious, painful, and chronic (long-lasting) disease. It is an autoimmune disease - a disease where the body's immune system attacks healthy cells. When a person has RA, their immune system attacks the joints and the tissues around the joints in the body. This causes different problems, like:

• The capsules around the joints get swollen
• The body makes too much synovial fluid (the special fluid that is supposed to cushion the joints)
• Tough fibrous tissue builds up in the synovium area (which is also supposed to help cushion the joints)