Metal Allergy and Contact Urticaria

Despite the frequent and widespread exposure to metals, few cases of contact urticaria caused by metals have been reported. The majority of cases are found among persons with occupational exposure to metals, especially in an industrial setting. Often, the symptoms of contact urticaria do not occur until after several years of exposure. The majority of cases are caused by exposure to nickel, but also aluminum, chromium, cobalt, and the metals belonging to the platinum group elements have been reported to induce urticarial reactions. All metals involved in contact urticaria belong to the transitional metal group and are primarily allergenic as salts and not in their metallic form. Although the mechanism behind metal-induced contact urticaria is unclear, most published cases report a relevant positive skin prick test, indicating involvement of an IgE-mediated mechanism or nonspecific release of histamine.