Contact allergens for the allergist

The objective of this article is to provide an overview and describe typically encountered skin contact allergens implicated in allergic contact dermatitis (ACD).

Published literature obtained through textbooks, online PubMed, and Google Scholar database searches, author photography, and adapted figures were used.

Studies on the evaluation of ACD and specific skin contact allergens were selected, with a focus on original research articles and clinical reviews.

Major classifications of common contact allergens include the following: (1) fragrances, (2) preservatives, (3) excipients, (4) rubber chemicals, (5) textile dyes, (6) topical medications, and (6) metals and other biomedical device components. The dermatitis distribution can aid in identifying the suspected contact allergen culprit. Certain contact allergens have features that are important to consider in the patch testing (PT) interpretation; these include possible irritant reactions, false-negative reactions or missed detection, and delayed reactions. Fragrances, preservatives, and excipients are culprits in personal products and facial or neck dermatitis. Patch testing with fragrances, preservatives, and patient-supplied products requires careful interpretation. Hand or foot dermatitis may be attributed to rubber chemicals or textile dyes. The management of topical corticosteroid contact allergy is guided on the basis of structural group classifications. Metal sensitization has been associated with dermatitis or biomedical device complications.

Each skin contact allergen has unique characteristics with regard to the dermatitis clinical presentation and potential PT nuances. These features are critical to recognize in the evaluation of ACD and PT interpretation and clinical relevance, leading to an accurate diagnosis.