Allopurinol is a prescription medication used to treat gout, high levels of uric acid, and kidney stones.  Allopurinol belongs to a group of drugs call xanthine oxidase inhibitors, which work by decreasing uric acid in the body. High levels of uric acid may lead to gout attacks or kidney stones.

This medication comes in tablet form and is taken once a day or in divided doses, with food and water. It is also in an injectable form to be given into the vein (IV) by healthcare professional.

Common side effects of allopurinol include diarrhea, nausea, and rash. Allopurinol can also cause drowsiness. Do not drive or operate heavy machinery until you know how allopurinol affects you.