Allergens in Atopic Dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex relationship to allergens. While AD itself is not an allergic reaction and does not necessarily involve allergen sensitization, AD patients show higher rates of sensitization to food and inhalant allergens compared to the general population. Recent evidence refining the "dual allergen exposure hypothesis" demonstrates that early oral exposure to allergens through an intact gastrointestinal barrier typically promotes tolerance, while exposure through compromised skin or respiratory barriers often leads to sensitization. Therefore, the impaired skin barrier function in AD patients increases the risk of transcutaneous sensitization and may interfere with oral tolerance development. Interestingly, AD patients' sensitivity to contact allergens (such as metals and fragrances) is not necessarily higher than that of the general population, which may be related to the inherent properties of these allergens. Personalized allergen testing can help guide appropriate allergen avoidance and reintroduction strategies in AD management. The insights into optimal allergen exposure conditions have also expanded the potential applications of allergen-specific immunotherapy in preventing AD onset in high-risk populations and halting the atopic march.