Prevalence: 13% in children, 2–3% in adults (similar in Germany and Taiwan)
Age of onset: 60% before age 1, 85% before age 5
Atopic march: AD → food allergy → asthma → allergic rhinitis (about 30–50% progress in this sequence)
Will they grow out of it: 40–60% improve markedly before puberty; 30–50% persist into adulthood
Dupilumab: FDA-approved since 2023 for Infants ≥ 6 months (a paradigm shift)
Diagnosis — Hanifin Rajka Criteria
Atopic dermatitis is diagnosed clinically without need for blood test or biopsy. Hanifin and Rajka (1980) remains the gold standard.
Major criteria (≥ 3)
- Pruritus — infants present with irritability, rubbing, sleep disturbance
- Typical morphology and distribution (age-dependent)
- Chronic or recurrent course
- Personal / family history of atopy (asthma, allergic rhinitis, atopic dermatitis)
Age-Specific Distribution
- Infancy (0-2 yo): cheeks, forehead, scalp; symmetric erythema, oozing, crusting; trunk and extensor surfaces; diaper area usually spared
- Childhood (2-12 yo): flexural surfaces (antecubital, popliteal), neck, wrists, ankles; lichenification from scratching
- Adolescent and adult (> 12 yo): continued flexural + head/neck/upper body; hand eczema; eyelid eczema
Bathing & Moisturizing Principles
- Water 32-37°C; 5-10 min; avoid prolonged or frequent bathing
- Soap-free, low pH 5.5, fragrance-free cleanser
- Pat dry (no rubbing); apply moisturizer within 3 minutes
- Ceramide / cholesterol / fatty acid (3:1:1) ratio moisturizers — repair barrier
- Avoid alcohol, fragrance, AHAs, retinoids, high-concentration essential oils
- Adjust formulation by season: oily ointment in winter, lighter cream/lotion in summer
Topical Corticosteroids — Pediatric Safe Use
| Site | Recommended class | Examples | Duration |
|---|---|---|---|
| Face, eyelids, genitals, axilla, groin | Class VI-VII (mildest) | Hydrocortisone 1%, Desonide 0.05% | Daily 1-2× × ≤ 7 days; consider TCI for frequent use |
| Trunk, extremities (general) | Class IV-V (mid-mild) | Triamcinolone 0.1%, Hydrocortisone valerate 0.2% | 1-2× daily 7-14 days acute; weekend therapy maintenance |
| Thicker skin / chronic lichenification | Class III-IV (mid-strong) | Mometasone 0.1%, Fluocinolone 0.025% | 1-2× daily ≤ 14 days |
| Palms, soles | Class II-III (strong) | Betamethasone 0.05% | Short term, ≤ 2 weeks |
Proactive maintenance therapy (Werfel 2024 ↑↑ strong recommendation): in remission, apply low-strength steroid or TCI to prone sites twice weekly — significantly reduces flares.
Topical Calcineurin Inhibitors (TCI) — Face Preferred
- Tacrolimus 0.03%: ≥ 2 yo; daily 1-2×; long-term safe
- Tacrolimus 0.1%: ≥ 16 yo
- Pimecrolimus 1%: ≥ 3 months (infant approved); 2× daily
Advantages: no skin atrophy, suitable for face/eyelids/genitals long-term. Initial burning sensation in ~30% (resolves in 3-5 days). Avoid sun exposure post-application; FDA black-box warning for theoretical lymphoma risk has been refuted by 20-year safety data. Crisaborole 2% (PDE-4 inhibitor): approved ≥ 3 months, 2× daily, non-steroid alternative.
Allergy Testing — When?
Werfel 2024 strongly opposes "comprehensive allergen screening" in all AD children. Reasons: high false-positive rate, blind avoidance causes nutritional and social problems.
Indications for testing: clear temporal correlation (food → flare within 30 min - 2 h); concomitant urticaria / angioedema / anaphylaxis history; moderate-severe AD in infants (high allergy risk) — may consider screening for not-yet-tolerated foods (egg, milk, peanut, wheat, soy, nuts, fish); refractory severe disease.
Atopy patch test ↓↓ NOT recommended in routine diagnostics. Positive test ≠ true allergy — confirm clinical relevance via elimination + provocation.
Dupilumab in Infants ≥ 6 Months
Approved 2023 by EMA / FDA / TFDA for severe AD in children as young as 6 months. Paller et al., Lancet 2022 (n = 162, 6 months-5 years): IGA 0-1 at week 16 was 28% vs 4% (p < 0.0001); EASI-75 53% vs 11%; conjunctivitis 5% vs 0%; no severe AEs. Dosing: 5-15 kg → 200 mg q4w; 15-30 kg → 300 mg q4w. Approved for moderate-to-severe AD failing standard topical therapy.
Atopic March — Prevention
30-50% of AD children develop food allergy → asthma → allergic rhinitis. Skin barrier hypothesis: barrier breakdown → transcutaneous allergen sensitization → systemic atopy.
Evidence-based prevention: aggressive AD control, avoid smoking, breastfeeding (mixed data), timely introduction of allergenic foods (LEAP, EAT trials). NOT proven: blanket low-allergy formula (without confirmed milk allergy), probiotics (mixed), Vitamin D supplementation in repleted children.
Infant Food Introduction — LEAP / EAT Trials Reversed Old Dogma
- Old paradigm (refuted): delay allergenic foods longer = better
- New paradigm (2015-2024): introduce peanut, egg, etc. at 4-6 months in moderate-risk infants → significantly lower allergy risk
LEAP trial (Du Toit, NEJM 2015): peanut allergy at 5 yo: 3.2% vs 17.2% (early peanut vs avoidance) — 81% reduction. EAT trial: early introduction of 6 allergenic foods at 3 months reduced multiple food allergies.
Practical guidance: introduce solids 4-6 months including allergenic foods; high-risk infants (severe AD or known allergy) — refer to allergy specialist for screening before introduction; one new food at a time, 48-hour observation; breastfeeding mothers don't need to avoid specific foods unless infant has confirmed allergy.
Summary — 5 Care Principles for Pediatric AD
- Daily liberal moisturization: within 3 min of bath, 2-3×/day — cheapest most effective treatment
- Aggressive acute treatment: appropriate-strength topical steroid, don't delay
- Proactive maintenance: low-strength TCS / TCI 2×/week to prone sites prevents flares
- Don't blindly avoid foods: introduce allergenic foods at 4-6 months unless confirmed allergy
- Don't endure moderate-severe disease: discuss Dupilumab / JAK with dermatologist when standard fails