Having been approved for medical use in the United States in 1966, Allopurinol is a medication used to decrease high blood uric acid levels. In fact, it is specifically used to prevent gout and specific types of kidney stones, not to mention that it is also used for the high uric acid levels that can occur with chemotherapy. It is worth noting that Allopurinol is an inhibitor of the enzyme xanthine oxidase, which in turn is responsible for the successive oxidation of hypoxanthine and xanthine, resulting in the production of uric acid. Bear in mind that Allopurinol’s side effects include the following: itchiness and rash (when taken by mouth), vomiting and kidney problems (when injected).