Patients with multiple contact allergies: a review.

Patients with multiple contact allergies, also referred to as polysensitized, are more frequent than predicted from prevalence of single sensitivities. The understanding of why some people develop multiple contact allergies, and characterization of patients with multiple contact allergies is limited. This review presents the current knowledge on the topic and discusses the evidence and characteristics of an increased susceptibility factor, possible causes to and genetic markers for the increased susceptibility, composition of the patient group and identification of patients at risk of developing multiple contact allergies. Evidence of allergen clusters among polysensitized individuals is also reviewed. The literature supports the idea that patients with multiple contact allergies constitute a special entity within the field of contact allergy. There is no generally accepted definition of patients with multiple contact allergies. We suggest that contact allergy to 3 or more allergens are defined as multiple contact allergies.