Atopic dermatitis (eczema)

Atopic dermatitis, commonly called eczema, is a long-term inflammatory skin condition characterised by dry, itchy, red and inflamed skin that flares and settles over time. It usually begins in childhood, often improving with age, but can persist or start in adults. Two things underlie it: a defective skin barrier that loses moisture and lets in irritants and allergens, and an over-reactive, allergic-leaning immune system — which is why it runs in families and clusters with asthma and allergic rhinitis (the atopic triad). The itch is central and drives a scratch–itch cycle that damages the skin further. Flares can be triggered by dryness, soaps and detergents, heat and sweat, stress, certain fabrics, and sometimes specific allergens. Broken, weepy or crusted skin can become infected. It is diagnosed clinically, from the appearance, distribution and history, rather than by blood tests.

• Diagnosis is clinical — from the typical itchy rash, its distribution (skin creases in children), and a personal or family history of atopy; blood tests are not usually needed.
• Total IgE — often raised, reflecting the atopic tendency, but non-specific.
• Eosinophils — may be mildly raised.
• Allergen-specific IgE / skin-prick testing — only when a specific allergic trigger is suspected and identifying it will change management.
• Skin swab — if infection is suspected in weepy, crusted or worsening eczema.

• Dry, itchy, red or inflamed skin, in a relapsing pattern
• Intense itch, often worse at night, disturbing sleep
• In children, typically in the creases of the elbows and knees, and on the face
• Thickened, leathery skin from long-term scratching
• Weeping, crusting or pustules if the skin becomes infected
• A personal or family history of eczema, asthma or hay fever