Rheumatoid arthritis (RA) is an inflammatory disease mainly affecting joints and tendons. Inflammation means swelling and heat. An inflamed joint is swollen, reddened and is warm to the touch. In most diseases, inflammation serves a purpose – it helps healing and, when healing is done, the inflammation goes away. In rheumatoid arthritis the opposite happens.

The inflammation causes damage – it can go on for a long time, or come and go. When it is active – known as a flare-up – you may feel unwell.

The body’s natural defences (the immune system) are part of the problem in rheumatoid arthritis. It somehow puts itself into reverse and attacks certain parts of the body instead of protecting it. This auto-immune reaction occurs mainly in the joints, but in a flare-up other organs can be affected. It is not known what causes the immune system to react in this way.

You can find out more about the condition in our Living with Rheumatoid Arthritis booklet.