Allopurinol hypersensitivity syndrome

Allopurinol hypersensitivity syndrome typically occurs in persons with preexisting kidney failure. Weeks to months after allopurinol is begun, the patient develops a morbilliform eruption or, less commonly, develops one of the far more serious and potentially lethal severe cutaneous adverse reactions viz., the DRESS syndrome, Stevens Johnson syndrome, or toxic epidermal necrolysis. 