Gout is caused by small crystals forming in the joints, resulting in severe pain, tenderness and swelling.
These crystals can grow when a waste product called uric acid starts to build up to high levels in the body.
Uric acid is created when the body breaks down chemicals known as purines.
If your kidneys don’t filter out enough uric acid, or your body is producing unusually high levels of it, it can build up in the body and turn into microscopic crystals.
These crystals usually form in and around the joints, possibly because the temperature in these areas is slightly lower than the rest of the body. If they get into the space between joints, the crystals can cause painful inflammation (redness and swelling).