Management of chronic spontaneous urticaria exacerbated by antihistamines: When treatment can act as a causal agent itself

© 2016 The Authors. Although H1-antihistamines currently constitute the largest class of medications used in the treatment of allergic disorders, some cases of hypersensitivity reactions due to various antihistamine preparations, such as fixed drug eruptions, contact dermatitis, maculo-papular rash, and urticarial reactions, have been reported (1). We report here 2 cases of patients with chronic spontaneous urticaria (CSU) in which antihistamines were an exacerbating factor of the disease and alternative treatment was required. The underlying mechanism in these cases is not entirely clear, but a type-I (immediate) hypersensitivity reaction should be considered.