Gout is a type of arthritis that is caused by having too much uric acid in the joints. Uric acid is a substance that forms when your body breaks down a substance called purines. Uric acid usually dissolves in your blood and passes through your kidneys into your urine. In people with gout, uric acid builds up and forms sharp crystals that can collect around the joints. This causes pain and swelling in the affected joints.
The pain can be very intense and can occur suddenly for no apparent reason. It often affects the big toe joint and it usually occurs at night. The affected joint becomes red, feels hot and hurts a lot. It will be more painful if you touch it. Other parts of the body where gout attacks occur include the top of the foot and the ankle joint. Gout can affect other joints in your body but it is most prevalent in the foot.