BackgroundDrug hypersensitivity is defined as any unfavorable reaction that occurs after the administration of any drug. It may or may not be mediated by the involvement of the immune system. Epidemiological data related to drug hypersensitivity reactions in our country are scarce.ObjectiveTo determine the prevalence of drug hypersensitivity in a group of young adults, as well as to identify associated factors.MethodsA structured questionnaire was applied to young people aged 18 to 25 years. The instrument was oriented to identify reactions of drug hypersensitivity, as well as the most prevalent drugs involved. In addition, a personal and family history of atopic diseases was included. Analysis for associations between variables was been done through logistic regression.ResultsThe prevalence of drug hypersensitivity reactions was 12% (144 of 1,200). The antibiotics were the agents most related to hypersensitivity reactions (9.8%) followed by nonsteroidal anti-inflammatory drugs (1.6%). Factors associated with drug hypersensitivity were a personal history of asthma, odds ratio (OR) 3.15 (95% confidence interval [CI], 1.44–6.91), maternal and paternal history of drug hypersensitivity, OR 2.33 (95% CI, 1.21–4.48) and OR 3.11 (95% CI, 1.22–7.92), respectively.ConclusionThe results of this research show that drug hypersensitivity in young adults is a highly prevalent event and it is associated with personal history of asthma and history of drug hypersensitivity in parents.