[Drug allergy].

Drug allergies can cause a great variety of symptoms and can thus imitate various diseases, like in previous times the lues. Drug allergies can be classified into three subgroups, which differ in their pathophysiology and require different diagnostic steps: firstly, classical drug allergies which are directed to the drug itself, a reactive compound of it or some contamination of the drug; secondly, pseudoallergic reactions which are caused by nonimmune mediated degranulation of mast cells and basophils; and thirdly, autoimmune reactions in which the drug elicits an immune reaction to autologous structures. A very detailed (criminalistic) history has the highest priority for the clarification of a suspected drug-allergic reaction; in addition, skin tests, serological tests and the lymphocyte transformation test might be useful. One should differentiate between tests which imitate the drug-elicited allergic reaction (i.e. Coombs test in drug induced hemolytic anemia) and tests which solely indicate a sensitization, these tests should be interpreted accordingly.