Allopurinol hypersensitivity syndrome
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 . 
<triplet> DRESS syndrome <subj> severe cutaneous adverse reactions <obj> subclass of <triplet> Stevens Johnson syndrome <subj> severe cutaneous adverse reactions <obj> subclass of <triplet> toxic epidermal necrolysis <subj> severe cutaneous adverse reactions <obj> subclass of