Juvenile rheumatoid arthritis (JRA) is a condition in children that involves joint pain and inflammation for more than six weeks. It is the most common chronic arthritis in children. Girls are affected twice as often as boys.

The cause of JRA is not well understood. It is an autoimmune disease, which means the immune system attacks normal body cells in the joints. This causes inflammation and pain in the joints. Although the immune response may trigger the inflammation, it is not known what causes the immune system to do so.

JRA may affect only a few joints, frequently the knees or hips. Other types of JRA affect many joints and other systems in the body as well. Many children with JRA may have inflammation in the eyes, which requires regular monitoring because it might not produce symptoms.

Physicians may use multiple blood tests and a physical examination to diagnose JRA. JRA cannot be cured although most children outgrow the symptoms when they reach adulthood. Treatment concentrates on pain relief and protecting growing joints. Drug treatment may include pain relievers and anti-inflammatory drugs. Other drugs modify the disease progress or work on parts of the immune system that malfunction to trigger JRA.