Key Facts

Eczema is one of the most common reasons for dermatology referral. The stepwise approach to treatment - emollients first, then topical steroids, then immunomodulators - is a frequent exam topic.

Epidemiology

• Atopic eczema: 15–20% of children; 2–5% of adults
• Peak onset: first year of life (~60% by age 1; ~90% by age 5)
• Increasing prevalence in developed countries ('hygiene hypothesis')
• ~50% resolve by teenage years; some persist into adulthood

Aetiology

• Genetic: filaggrin gene (FLG) loss-of-function mutations - defective skin barrier; strongest genetic risk factor
• Environmental: allergens, irritants, infections, stress

Pathophysiology

• Th2-predominant immune response → IL-4, IL-13, IL-31 (itch mediator)
• IgE sensitisation to environmental allergens
• Skin microbiome disruption: S. aureus colonisation in >90% of atopic eczema

Infants

• Face, scalp, extensor surfaces
• Erythematous, weeping, crusting

Children/Adults

• Flexural distribution: antecubital fossae, popliteal fossae, wrists, neck
• Dry, lichenified (thickened) skin
• Excoriations from scratching
• Sleep disturbance from pruritus

Variants

• Discoid (nummular): coin-shaped, well-demarcated plaques
• Seborrhoeic: scalp, nasolabial folds, eyebrows (Malassezia-related)
• Varicose (stasis): lower legs with venous disease
• Pompholyx: vesicles on palms/soles

Red Flags

• Eczema herpeticum: widespread punched-out erosions, fever, malaise - dermatological EMERGENCY
• Secondary bacterial infection: crusting, weeping, pustules (S. aureus)
• Erythroderma: >90% BSA involved - risk of hypothermia, fluid loss

Bedside

• Clinical diagnosis in most cases - no investigations routinely needed
• Skin swab: if secondary infection suspected (S. aureus, HSV)
• Dermatoscopy: if diagnostic uncertainty

Bloods

• Total IgE: often elevated in atopic eczema (non-specific)
• Specific IgE / skin prick testing: if food allergy suspected (especially children <2 with moderate-severe eczema)

Special Tests

• Patch testing: if allergic contact dermatitis suspected - apply allergen panels for 48 hours, read at 48 and 96 hours
• Skin biopsy: rarely needed; spongiotic dermatitis on histology
• SCORAD / EASI score: validated severity assessment tools

Stepwise Approach (NICE NG190)

Step 1 - Emollients (ALL patients):

• Liberal use: 250–500g/week; apply frequently (at least 3–4 times daily)
• Leave-on emollients: Cetraben, Doublebase, Diprobase, Epaderm
• Soap substitutes: use emollient as wash
• Pat dry, apply emollient within 3 minutes of bathing

Step 2 - Topical Corticosteroids:

• Mild: hydrocortisone 1% (face, children)
• Moderate: clobetasone butyrate 0.05% (Eumovate)
• Potent: betamethasone valerate 0.1% (Betnovate); mometasone furoate 0.1%
• Very potent: clobetasol propionate 0.05% (Dermovate) - short courses only
• Use fingertip unit (FTU) dosing; apply thinly once daily

Step 3 - Topical Calcineurin Inhibitors:

• Tacrolimus 0.03% (children) or 0.1% (adults) - for face, flexures, steroid-sensitive areas
• Pimecrolimus 1% - mild-moderate disease
• No skin atrophy risk

Step 4 - Specialist Therapies:

• Phototherapy: narrowband UVB
• Systemic immunosuppressants: methotrexate, azathioprine, ciclosporin
• Biologics: dupilumab 300mg SC every 2 weeks (anti-IL-4Rα) - NICE TA534
• JAK inhibitors: baricitinib, upadacitinib, abrocitinib (NICE approved)

Infection Management

• Bacterial (S. aureus): flucloxacillin 500mg QDS 7 days; topical fusidic acid 2%
• Eczema herpeticum: IV aciclovir 5mg/kg TDS - EMERGENCY

Referral Criteria

• Dermatology: moderate-severe eczema unresponsive to topical treatment
• Allergy clinic: suspected food allergy trigger
• Urgent: eczema herpeticum, erythroderma

• ~50% of childhood eczema resolves by teenage years
• ~20% have persistent disease into adulthood
• Filaggrin mutations predict more severe and persistent disease
• Quality of life significantly impacted (sleep, psychosocial)
• Eczema herpeticum: mortality <1% with prompt treatment; can be fatal if untreated

Topical Steroid Potency Ladder

Fingertip Unit (FTU) Guide