The simple answer—excess uric acid. When the level of uric acid in blood is high (because of excessive production in the body and/or high-uric acid diet), the excess acid forms tiny crystals, which then gets lodged into the internal crevices of the body (mostly the joints and the tendons), disrupting normal functions and causing swelling, pressure, tenderness, and severe pain. While scientists and professionals are not exactly clear on why these painful gout inflammations develop, one of the most common factors that increase risk is a diet that is high in purines.
Gout attacks are unpredictable. Symptoms may develop slowly or rapidly over a few hours and then last for days, after which the problem area (joint) may start feeling normal again, completely free from pain or discomfort. First gout attacks commonly target the joint of the big toe, with symptoms often developing at night, although signs can also occur any time. Watch out for common gout symptoms such as inflammation, peeling and itchy or red and shiny skin over the joint and swelling and intense pain in the affected area.