Hair Dyes Sensitization and Cross-Reactions: Challenges and Solutions: A Systematic Review of Hair Dye Allergens' Prevalence

Widespread use of oxidative hair dyes during the past decades has raised questions on the potential allergy reactions and their management, as well as prevention measures for both professionals and consumers. Allergic contact dermatitis can be elicited by various hair dye-related allergens, though the main problem remains with p-phenylenediamine and related aromatic amines. If allergy is suspected, patch testing identifies the responsible hapten. Individuals sensitized to specific permanent hair dyes substances should avoid the exposure to these chemicals, but also be aware of possible cross-sensitization to other similar compounds. Cross-reactions detected in patch-tested populations indicate that one cannot safely use alternatives, although cross-reactivity is not always clinically relevant. An open application hair dye allergy self-test is recommended by manufacturers for early detection of allergy predisposition in consumers, although the lack of standardized conditions makes the efficacy of this process doubtful. Appropriate use of hand gloves, especially nitrile, is the most efficient prevention measure for professional hand eczema. In this systematic review, we focus on cross-reactions among hair dye-related allergens and make an attempt to answer some, frequently encountered by physicians, questions, while presenting the prevalence of the hair dye-related allergens.