I Am A Male, Age 66, With Obesity. I Have

I am a male, age 66, with obesity. I have been taking allopurinol for gout for three or four months. I find that it creates a malaise in me that makes it difficult for me to even put in eight hours of work a day. Therefore I want to get off allopurinol. My question is: What kind of a bad reaction might I receive if I suddenly stop taking allopurinol?