Gout causes attacks of painful inflammation in one or more of your joints. It is caused by a build-up of a naturally occurring chemical in your blood, called uric acid (urate). From time to time, the level of uric acid in your blood may become too high and tiny grit-like crystals may form, which typically collect in your joints and tendons. The crystals irritate the tissues of the joint to cause inflammation, swelling, and pain.
This is a companion discussion topic for the original article at https://patient.info/medicine/allopurinol-zyloric