DRUG ALLERGY

Drug allergies can be classified into three sub-groups which differ in their pathophysiology and require different diagnostic steps: 1. clas sical drug allergies, which are directed against the drug itself, a re active metabolite or some contaminant of the drug, 2. pseudoallergic r eactions, which are caused by non-immune mediated degranulation of mas t cells and basophils, and 3. autoimmune reactions, in which the drug elicits an immune reaction to autologous structures. A very detailed a ccurate history is of the greatest importance in the clarification of a suspected drug allergic reaction, as well as experience with the dru g. In addition, skin tests, serological tests and the lymphocyte trans formation test may be useful. One should differentiate between tests w hich imitate the drug-elicited allergic reaction (i.e., Coombs test in drug-induced hemolytic anemia) and tests which solely indicate a sens itization and the tests must be interpretated accordingly.