Allopurinol-induced hypersensitivity syndrome

Abstract

Allopurinol is an effective urate lowering drug, which is usually well-tolerated with no adverse effects in most cases, but about 2% of the treated patients develop a skin rash, and patients may experience severe allopurinol-induced hypersensitivity syndrome. The aim of the authors was to summarize and present the clinical manifestations of allopurinol-induced hypersensitivity in patients treated at the Department of Dermatology and Allergology, University of Szeged in order to identify potential associations with this syndrome. Retrospective review of all patients who were referred to the department with allopurinol-induced hypersensitivity syndrome in the last four years. During four years, 11 patients were treated with allopurinol-induced hypersensitivity syndrome. The average age was 70.3 years. Before the initiation of allopurinol therapy, 36% of patients had already suffered from various degrees of renal impairment, and 72% of them had been taking thiazide diuretics. Cutaneous manifestations were mainly generalized, erythematous, maculopapular exanthemas (9 patients, 82%), and two patients showed signs of erythema multiforme (18%). Asymptomatic hyperuricemia was the indication for allopurinol therapy in all patients. Allopurinol-induced hypersensitivity syndrome is a severe, life-threatening disease. Administration of allopurinol should be initiated with clear indications in appropriate dose. Old age, underlying renal impairment and concomitant thiazide diuretic intake should be considered as potential risk factors for developing hypersensitivity syndrome.