Allopurinol is a xanthine oxidase inhibitor used to prevent attacks of gout. Therefore, it will not be useful if you take it once a gout attack has started. Allopurinol is available in tablets for oral administration that should be taken once or twice a day after you have a meal. Take allopurinol regularly without missing doses to make sure you benefit from the treatment. Even if your symptoms improve, keep taking this medicine as directed to make sure you feel its effects. Several months can pass before you will be able to notice significant improvement of your condition.

Certain drugs you are taking can decrease, increase or alter the effects of allopurinol. Make sure your health care provider knows that you are taking blood thinners, cancer chemotherapy drugs, immune system suppressants, diuretics, other drugs for the treatment of gout, and any supplements or vitamins. Diarrhea, drowsiness and upset stomach are the few side effects that may be caused by the treatment. More serious side effects that have to be reported to your doctor as soon as possible include eye irritation, skin rash, loss of appetite, weight loss, itching, blood in the urine, swelling of the mouth, sore throat, chills and fever.