[Diagnostics of drug hypersensitivity reactions].

Drug hypersensitivity reactions comprise approximately 25% of all adverse drug reactions and can be classified into allergic and pseudoallergic drug reactions. Immediate type anaphylactic and delayed type rash reactions of various clinical patterns can be distinguished, depending on the pathogenesis and clinical symptoms. The diagnostic work-up encompasses a thorough but also focused evaluation of the medical history, skin tests and when indicated challenge tests. Furthermore, in vitro tests, such as basophil activation tests and T cell assays not only add valuable additional information but can also yield decisive results for the diagnosis, especially in cases of severe drug reactions or reactions which cannot be further clarified by provocation tests. The aim of these measurements is not only the proof of drug intolerance and the detection of the causal drug but also the disclosure of the type of adverse reaction and the identification of potential, tolerated alternative drugs. This information is very important for the counseling of the patient and for prevention of new drug hypersensitivity reactions in the future.