Allergic Contact Dermatitis

Abstract

Abstract Allergic contact dermatitis is considered to be a prototype of delayed hypersensitivity reactions requiring two phases – induction and elicitation. The amount of allergen per skin surface area is the key factor that determines the risk of induction. Exposure‐related factors that influence the elicitation phase include allergen concentration (dose), duration and frequency of exposure, the matrix, the presence of irritants and the region of application. A diagnosis of allergic contact dermatitis requires careful evaluation of a patient's clinical history when the suspicion is aroused, physical examination, and various types of skin testing (patch testing, photopatch testing and repeat open application tests. During the last few decades much effort has been put into standardisation of allergens, vehicles, test concentrations and the scoring of test reactions. This chapter provides information on the diagnosis and management of allergic contact dermatitis and information on the major allergens involved in regional dermatitis.