Allopurinol belongs to a class of drugs called xanthine oxidase inhibitors. It is a hyperuricemic agent that is used to treat or prevent gout attacks, high levels of uric acid in the body caused by certain cancer medications, and to prevent kidney stones from developing.
Allopurinol works by reducing the production of uric acid. It comes as a tablet to take by mouth once or twice daily, after a meal. It normally takes several months before you start to feel the benefit of the medicine.
Common side effects of Allopurinol contain sleepiness, upset stomach or diarrhea.
Allopurinol may be used as treatment for other medical conditions, as suggested by your doctor.