[Comment] Modelling allopurinol-induced severe adverse cutaneous reactions

Severe adverse cutaneous reactions, including Stevens–Johnson syndrome, drug rash with eosinophilia and systemic symptoms, and toxic epidermal necrolysis, are serious and life-threatening but fortunately rare adverse events associated with allopurinol. Although the incidence of allopurinol-induced severe adverse cutaneous reactions is low (estimated 0·69 cases per 1000 person-years),1 the resulting substantial morbidity and mortality mean any reasonable steps to prevent occurrence of severe adverse cutaneous reactions should be implemented.