The Core Distinction
Eczema (atopic dermatitis) and psoriasis are both chronic inflammatory skin conditions, but they are mechanistically distinct. Getting the diagnosis right is critical — because the approaches differ:
| Eczema (Atopic Dermatitis) | Psoriasis | |
|---|---|---|
| Primary defect | Filaggrin gene mutation → barrier dysfunction → IgE sensitisation | T-cell dysregulation → keratinocyte hyperproliferation → accelerated turnover |
| Appearance | Weepy, crusting, intensely itchy; flexural creases | Well-defined plaques with silver scale; extensor surfaces |
| Age of onset | Usually infancy/childhood; often persists | Any age; typically late teens onward |
| Trigger mechanism | Barrier disruption → allergen penetration → immune response | Stress, injury (Koebner), infection, certain medications |
Eczema: The Barrier-First Protocol
The fundamental defect in atopic dermatitis is a filaggrin gene (FLG) mutation — filaggrin is a structural protein essential for stratum corneum barrier integrity. Without adequate filaggrin, the barrier becomes permeable to allergens and irritants, triggering the Th2-dominant immune response that characterises atopic dermatitis.
- First priority: Restore and maintain the barrier continuously
- Apply ceramide-rich emollients immediately after bathing ("soak and seal")
- Use only fragrance-free, hypoallergenic products — fragrance is the primary eczema sensitiser
- Avoid known triggers: dust mites, pet dander, certain food allergens in sensitised individuals
- Medical management: Topical corticosteroids (TCS) for flares; dupilumab (IL-4/IL-13 blocker) for moderate-severe — requires dermatologist
Psoriasis: Managing Hyperproliferation
Psoriatic skin turns over in 3–5 days (vs 28 days for normal skin) — driven by activated T-cells releasing TNF-α, IL-17, and IL-23. This creates the thick, scaly plaques characteristic of the condition.
- Keratolytics: Salicylic acid (2–10%) physically removes scale build-up
- Vitamin D analogues (Rx): Calcipotriol inhibits keratinocyte proliferation and promotes differentiation
- Coal tar: Anti-proliferative and anti-inflammatory; messy but effective for scalp psoriasis
- Biologics (Rx): Secukinumab, ixekizumab (anti-IL-17), ustekinumab (anti-IL-23) — for moderate-severe systemic disease
Both conditions benefit from: Stress management (cortisol exacerbates both), consistent emollient use between flares, fragrance-free skincare, and identifying individual triggers through a structured elimination approach.
For the gut-skin connection in eczema, see Gut-Skin Axis. For the stress-skin link, see Psychodermatology.