Eczema and atopic dermatitis

Atopic dermatitis is a barrier disease: a defective skin barrier (commonly a filaggrin variant) lets irritants in and water out, and the immune system responds. The treatment follows directly from that.

Emollients, used generously and often, are the treatment. The evidence is clear and unglamorous: liberal and frequent application of an emollient reduces flares, reduces steroid requirement and improves the barrier. The standard failure is using a fraction of the amount needed — think of an emollient as a prescription with a dose, not a cosmetics habit. 250-500 g per week for an adult with widespread eczema is the right order of magnitude.

Topical corticosteroids for flares, at the right potency for the site, used properly. The fear of topical steroids among patients is common, disproportionate, and is a cause of undertreatment; thinning occurs with prolonged use of potent steroids on thin skin, not with proper use of an appropriate strength for a flare.

Colloidal oatmeal has randomised trial evidence for reducing itch, dryness and redness in atopic dermatitis, and it is a well-tolerated adjunct. A bath or a cream.

Vitamin D — low levels are associated with eczema severity, and supplementation has shown modest improvement in some trials. Correcting a deficiency is reasonable.

Other adjuncts with weak evidence: chamomile cream, licorice root extract (the deglycyrrhizinated form), and evening primrose oil (trials largely negative). Aloe vera gel is soothing.

What to avoid. Neat essential oils, which sensitise broken skin; "natural" preservative-free products that grow bacteria; wool next to the skin; soap, which strips the barrier — use a soap substitute; and fragrance, which is a common and under-recognised trigger of contact dermatitis.

The red flags. Eczema with extensive broken skin and fever; eczema that suddenly changes character; eczema with vesicles and pain suggesting a secondary herpes infection (eczema herpeticum), which is an emergency; and a sudden worsening of a stable eczema pattern, which is often contact allergy to something new.