Drug allergy (DA) is defined as hypersensitivity reactions to drugs mediated by specific antibodies or T lymphocytes. Its epidemiological risk factors are not fully understood and severe symptoms ranging from mild manifestations such as erythema, skin rash, and pruritus to anaphylaxis and mortality may be observed. Underdiagnosis and overdiagnosis are common problems in drug allergy and may deprive patients of optimal drug choices.1,2 DA may require hospitalization or prolong hospitalization depending on its severity. Adverse drug reactions present a serious problem, affecting 10-20% of hospitalized patients and more than 7% of the general population. Penicillin allergy is the most commonly reported drug allergy, with prevalence ranging from 5% in the general population to 15% in hospitalized patients.3,4