This is because the amount of allopurinol in your body is increased. Allopurinol may also be used for purposes not listed in this medication guide. High levels of uric acid may cause gout attacks or kidney stones. Allopurinol ( Zyloprim) is used for treating gout, high levels of uric acid in the body ( often caused by certain cancers and cancer treatments), and kidney stones. Allopurinol is used to treat gout and certain types of kidney stones and reduces the amount of uric acid made by the body in order to prevent a gout attack or flare up. How can the answer be improved? Allopurinol is used to treat gout or kidney stones, and to decrease levels of uric acid in people who are receiving cancer treatment. Allopurinol umflarea. Allopurinol is in a class of medications called xanthine oxidase inhibitors. Side effects from allopurinol: Taking allopurinol with certain medications raises your risk of side effects from allopurinol. It works by reducing the production of uric acid in the body.