[Hypersensitivity syndrome caused by allopurinol: report of 2 cases and review of the literature].

A severe adverse drug effect secondary to allopurinol ingestion has been described, characterized by fever, eosinophilia, cutaneous rash, hepatic lesion and renal failure, with a high mortality (21-26%) and unknown ethiopathogenicity. In many cases patients had a previous disorder on their renal function (53%) and more than half received allopurinol due to asymptomatic hyperuricemia. We present two new cases and review other 18 patients diagnosed in the last nine years, analyzing the ethiopathogenicity, epidemiological, clinical, therapeutical and preventive aspects.