Hypersensitivity reactions in neonates and infants.

Although rare, several hypersensitivity reactions can occur in the infant population. Several types of hypersensitivity reactions are discussed, including urticaria, drug eruptions, erythema multiforme, allergic contact dermatitis, and vasculitis (acute hemorrhagic edema of infancy); neonatal lupus also is discussed. Although most of these conditions are benign, their presentations can be dramatic and a cause of concern for both parents and physicians. Important considerations and differences in the diagnosis and management of these conditions in children under the age of 6 months are discussed.