Doctors don’t know the cause of rheumatoid arthritis, but there may be a strong genetic predisposition.
It is now understood that there is an abnormal immune reaction against the body's own synovial tissue, called an autoimmune reaction.
Other possible causes are environmental or biological triggers, like hormonal changes or a viral infection.
What is rheumatoid arthritis?
Omega-3s lower rheumatoid arthritis risk
Reviewed by Dr Dr I C Louw, Rheumatologist/Physician and Dr A Halland, Rheumatologist/Physician, March 2007