Drug hypersensitivities: definition, epidemiology and risk factors.

Drug hypersensitivity reactions are the adverse effects of drugs taken at a dose which is tolerated by normal subjects, and which clinically resemble allergy. There is few true epidemiological data on drug hypersensitivity reactions. The available information requires a cautious interpretation as they are rarely proven. Both under diagnosis and over diagnosis must be taken into account. Drug hypersensitivity reactions represent one third of adverse drug reactions, can be life threatening and motivate changes on drug prescription. They concern more than 7% of the general population, therefore being an important public health problem. A few risk factors are already pinpointed. Future progress in genetics can help the identification of populations at risk for specific reactions. This review describes currently known data on incidence,prevalence, mor tality and risk factors of these reactions.