Drug allergies are heterogeneous and multifactorial. They can be life-threatening and lead to market withdrawal of particularly risky drugs. Immunological research has improved our understanding of drug allergies but has not yet been able to prevent them. In contrast, epidemiological research not only provides information on the incidence and risk factors of such reactions, but can now, in conjunction the most recent immunological data, also help to prevent some of them. For example, prior pholcodine consumption has been shown to increase the risk of anaphylaxis due to neuromuscular blocking agents during general anesthesia. This review examines the place of interventional epidemiology in the field of drug allergy, taking as examples both myorelaxant-induced anaphylaxis and abacavir-induced DRESS.