Atopic dermatitis.

Atopic dermatitis (AD) is the most common inflammatory skin disease and carries the highest disability-adjusted life-years burden, ranking 15th among all non-fatal diseases globally. It is characterized by intensely itchy skin and is associated with multiple comorbidities, such as food allergy, asthma, allergic rhinitis and eosinophilic oesophagitis, which are mainly driven by type 2 immune responses. Other comorbidities include mental health disorders, disordered bone health, and cutaneous and extracutaneous infections. AD is also associated with other immune-mediated inflammatory diseases, including alopecia areata, vitiligo and inflammatory bowel disease. AD most often starts in the first 2 years of life but can occur at any life stage and onset at >60 years of age is increasingly common. The twenty-first century has brought greater insights into disease pathology, with an understanding of the complex interplay between the skin barrier, cutaneous and systemic immune pathways, cutaneous microbiome and neural networks. This improved mechanistic understanding has enabled rational drug design and a shift from non-specific broad immunomodulation to targeted biologic therapies and small molecules for severe disease and from topical corticosteroids to next-generation therapies for mild and moderate disease. Yet, considerable global inequity remains in access to these novel therapeutics.