This is probably the most feared complication of Allopurinol hypersensitivity reactions, with as high as 25-50% mortality risk. Allopurinol should not be prescribed for hyperuricaemia without clear clinical indications. Care should be exercised especially in those with renal impairment. Those started on it should be cautioned to look out for signs and symptoms of possible allergy (itch, rash, mouth ulcers). HLA-B5801 is an expensive test which may help predict those at risk for developing the adverse reaction.
Asians, especially Han Chinese, Koreans and Thais appear to be most at risk for developing Allopurinol hypersensitivity reactions, if they are HLA-B5801 positive. But this test is costly, and not widely available.