Drug immunoallergic reactions: epidemiological and clinical data

Allergic and pseudoallergic reactions frequently occur in hospitalized pati ents and represent up to one-third of adverse drug reactions. Allergic reac tions are unpredictable reactions, related to immunologic mechanisms. pseud oallergic reactions mimic allergic reactions but no drug-specific antibody or T-cell proliferation can be demonstrated. Clinical presentations are num erous and heterogeneous, from a mild urticaria to a dramatic anaphylactic s hock and an extensive bullous skin disease. A true diagnosis is rarely set up and the tools for it are lacking. In this review, we will focus on some epidemiological data concerning these reactions, including data on incidenc e, mortality and cost.