Zyloric tablets contain the active ingredient allopurinol, a type of medicine that inhibits the conversion of purine (a substance found in high-protein foods, amongst other things) into uric acid. The excess of uric acid in the blood can cause a number of health problems, such as gout and kidney stones. It works by slowing down the speed of certain chemical reactions in your body to lower the level of uric acid in the blood and urine. Allopurinol is used to treat gout and certain types of kidney stones. It is also used to prevent increased uric acid levels in patients receiving cancer chemotherapy.