Gell and Coombs's classification: is it still valid?

The Gell and Coombs's classification divides drug allergies into four pathophysiological types, namely anaphylaxis (type I), antibody-mediated cytotoxic reactions (type II), immune complex-mediated reactions (type III), and delayed type hypersensitivity (type IV). Although this classification was proposed more than 30 years ago, it is still widely used. As only a limited number of drug allergies fit into this classification which does not include our current understanding of the immune response, its use is not recommended, particularly in the context of the preclinical safety evaluation of new therapeutic agents. In fact, three different situations can be identified, namely pseudo-allergic reactions, primarily antibody-mediated reactions and cell-mediated reactions, which could serve as a basis for modern and more adequate classifications