Rheumatoid arthritis is an autoimmune condition. That means the body’s immune system attacks the cells lining joints by mistake.
The immune system usually helps to fight off bacteria and viruses.
But, in rheumatoid arthritis patients, antibodies are sent to attack the tissue surrounding the joints.
This causes the cells covering joints to become inflamed and sore.
Once the cells lining joints become damaged, they release chemicals which destroy nearby cartilage, tendons, ligaments, and bones.
“If the condition isn’t treated, these chemicals gradually cause the joint to lose its shape and alignment,” said the NHS.
“Eventually, it can destroy the joint completely.”
Scientists still aren’t entirely sure what causes the immune system to attack joints.
Your risk of developing the condition increases if someone in your family also has rheumatoid arthritis.
Women are also more likely to develop the arthritis – possibly because of a link to the hormone oestrogen.
You’re more likely to get rheumatoid arthritis if you’re a smoker, than a non-smoker.
There’s currently no cure for the condition, but early diagnosis could help to ease symptoms.
Rheumatoid arthritis symptoms include joint pain, swelling and stiffness.
The lining of joints can often become inflamed, causing them to become hot and tender to touch.
On rare occasions, firm swellings can develop under the skin around the joints.
Some patients have also reported fatigue, a fever, weight loss, and a loss of appetite.