Abstract

Around 1 in 6 people have some form of allergy.1 The more common presentations include seasonal and perennial rhinitis, acute urticaria, immediate reactions to food and drugs and the early phase of atopic eczema and asthma. All of these are IgE mediated and classified as immediate (type I) hypersensitivity. Other presentations of hypersensitivity include transfusion reactions (type II; antibody reactions with antigens on cell surfaces), farmer's lung and bird fancier's disease (type III; immune complex-mediated reactions) and contact dermatitis and fixed drug eruptions like late reactions to antibiotics (type IV; delayed-type cell-mediated reactions).2 In this article we review the tests used for investigating patients with suspected type I hypersensitivity and consider their value in management.