Egg Allergy and the Skin: The Invisible Face of Epidermal Alteration in Infants

Introduction: Egg allergy is one of the most common food allergies in early childhood and often coexists with atopic conditions such as atopic dermatitis (AD) and urticaria. Skin-barrier dysfunction plays a critical role in the pathophysiology of allergic diseases. This study aimed to examine the relationship between egg allergy and skin-barrier health by evaluating hydration, sebum, and softness using a noninvasive bioimpedance method. Methods: In this prospective case-control study, 49 children aged 0–2 years with egg allergy and 50 age-matched healthy controls were enrolled between December 2024 and February 2025. In the case group, total and egg-specific IgE levels, eosinophil counts, and skin prick test results were recorded. Skin parameters were measured from the antecubital region using a portable bioimpedance device. Intergroup comparisons were performed using the Mann-Whitney U test. Additionally, an exploratory subgroup analysis compared skin parameters between egg-allergic children with and without AD exacerbation after allergic reaction. Results: Children with egg allergy had significantly lower skin hydration, sebum, and softness compared to controls (p < 0.001 for all). Total IgE levels were higher in egg-specific IgE-positive patients (p = 0.001), although skin parameters did not differ significantly by IgE status. Among 20 egg-allergic children with follow-up after allergic reactions, those with AD exacerbation had markedly lower moisture, oil, and softness scores than those without exacerbation (p < 0.01 for all comparisons). Conclusion: Children with egg allergy exhibit both elevated immunologic activity and impaired skin-barrier function. Bioimpedance analysis offers a practical and noninvasive tool for evaluating skin health in allergic infants. Integrating skin-barrier assessment into allergy management may facilitate early intervention and more comprehensive care.