Emollient Formulations and Skin Barrier Practices in the Context of Eczema and Food Allergy Prevention

The skin is far from a passive shield; it functions as a dynamic "living barrier" whose structural and immunological integrity is paramount in preventing atopic dermatitis (AD) and the subsequent progression of the atopic march toward food allergy (FA). While prophylactic emollient therapy has emerged as a promising strategy for primary prevention, recent large-scale randomized controlled trials have yielded conflicting results. In this review, we examine the complex interplay between emollient formulations, skin barrier biology, and immune responses in the context of AD and FA prevention. We discuss the functional roles of occlusives, humectants, and barrier-replenishing lipids, highlighting how their composition, ratios, and physicochemical properties determine their effects on barrier integrity. We further evaluate the impact of additional formulation components, including food-derived ingredients, haptens, irritants, and pH, as well as external factors such as product handling and application practices, which may inadvertently promote barrier disruption and transcutaneous sensitization. Collectively, current evidence supports a shift from generalized emollient use toward a precision-based, barrier-directed approach. Optimized formulations that restore physiological lipid composition, combined with early intervention and integration of objective biomarkers, may offer a more effective strategy to prevent AD and the atopic march.