Skin barrier and cutaneous microbiota in the primary prevention of atopic dermatitis: current evidence and future perspectives

Background. Atopic dermatitis (AD) is often the earliest manifestation of allergic multimorbidity in childhood. Epidermal barrier impairment and altered microbial colonization can be detected before overt disease, supporting a unified barrier-microbiota model of pathogenesis. Aim. To examine the biological basis and clinical evidence for primary prevention of pediatric AD through interventions directed at skin barrier function, microbial ecology, or both. Methods. Evidence from longitudinal cohorts, randomized trials, systematic reviews, meta-analyses, and international guidance was appraised narratively, with emphasis on pediatric populations and clinically diagnosed AD. Main findings. Current evidence highlights a complex and evolving preventive landscape. While large pragmatic trials have not demonstrated a consistent benefit of routine neonatal emollient use, emerging data suggest that timing, formulation, and biological risk stratification may influence preventive efficacy. Microbiota-directed strategies, especially selected probiotic interventions, have shown promising but strain- and timing-dependent effects, supporting further investigation of integrated barrier- and microbiota-based approaches. Conclusions. Infant skincare should not be presented as proven AD prevention. Future trials should enroll biologically defined risk groups, target prespecified windows, integrate barrier and microbial biomarkers, and use harmonized outcomes.