The Atopic March
Eczema (atopic dermatitis) is part of a broader pattern of atopic disease known as the atopic march. In susceptible individuals, atopic conditions tend to develop in a characteristic sequence:
- Eczema — often appears in infancy, affecting the face, scalp, and skin folds
- Food allergy — typically emerges in the first 1–2 years of life
- Allergic rhinitis (hay fever) — usually develops in childhood or adolescence
- Asthma — may follow, often triggered by the same allergens
Not every child follows this sequence, but the pattern reflects shared underlying mechanisms: impaired skin barrier function, abnormal immune responses, and IgE sensitisation that broadens over time.
How Allergens Trigger Eczema Flares
In atopic eczema, the skin barrier is disrupted — it is more permeable to allergens and irritants, and more prone to inflammation. Allergen exposure can trigger or worsen flares through two main routes:
- Direct skin contact: Exposure to allergens (pet dander, dust mite, pollen) through the damaged skin surface can provoke local inflammation.
- Systemic IgE-mediated response: Food allergens absorbed through the gut can trigger widespread skin inflammation in sensitised individuals.
In younger children, food allergens are particularly relevant — egg, milk, wheat, peanut and soy are the most common culprits. In older children and adults, aeroallergens (house dust mite, grass pollen, animal dander) become increasingly important drivers of flares.
Key Aeroallergen Components Tested by ALEX3
House dust mite
- Der p 1, Der p 2 — Dermatophagoides pteronyssinus
- Der f 1, Der f 2 — D. farinae
Grasses and pollens
- Phl p 1, Phl p 5 — timothy grass
- Bet v 1 — birch (cross-reactive)
Pet dander
- Fel d 1 — cat
- Can f 1 — dog
Moulds
- Alt a 1 — Alternaria alternata
- Cla h 8 — Cladosporium herbarum
When ALEX3 Testing Is Indicated in Eczema
Not all eczema patients need formal allergy testing. ALEX3 is most useful when:
- Eczema is poorly controlled despite regular emollients and topical steroids
- You or your child has a suspected food trigger (reactions to a specific food)
- Eczema is accompanied by other atopic features (rhinitis, asthma, recurrent hives)
- You want to understand which environmental allergens may be contributing to flares
Important: A positive IgE result does not automatically mean that allergen is causing your eczema — results must be interpreted in the context of your clinical history. Your GP will discuss with you what the results mean and whether avoidance measures are appropriate.
Book ALEX3 Allergy Testing
If you or your child has eczema that is proving difficult to control, ALEX3 testing at Lambert Medical can help identify allergic drivers and guide management. Our GP will review results with you in a follow-up appointment.