Understanding Eczema

What eczema is

Eczema, or atopic dermatitis (AD), is a chronic skin condition that causes dryness, itching, redness, and repeated flares. It affects roughly 15–25% of children in high-income countries (Langan et al., Lancet, 2020) and in most cases comes and goes rather than staying the same every day. It is one of the most common chronic conditions of childhood worldwide.

Why it happens

Eczema is shaped by several problems happening together:

• Skin barrier weakness: the outer layer of skin loses water easily and becomes dry; in some children this is partly genetic (loss-of-function mutations in the FLG gene, which encodes the protein filaggrin, are present in roughly 30% of children with AD in European populations — Palmer et al., Nature Genetics, 2006)
• Immune skewing: in eczema the immune system has a Th2/Th22 bias, meaning it overproduces certain inflammatory signals (notably IL-4, IL-13, IL-31, and TSLP) that drive inflammation and itch while suppressing normal barrier-repair responses
• Microbiome imbalance: the bacteria on eczema skin is often dominated by Staphylococcus aureus, which produces toxins, proteases, and superantigens that worsen inflammation; healthy skin has a more diverse bacterial community (Gallo & Horswill, J Invest Dermatol, 2024)
• The itch-scratch cycle: scratching damages the barrier further, allowing more irritants and bacteria in, which causes more inflammation and more itch

Many parents look for one hidden cause, but eczema is almost always a pattern problem driven by multiple interacting factors rather than a single trigger.

The atopic march

In susceptible children, eczema is often the first step in a sequence of atopic conditions:

1. Atopic dermatitis — usually appears first, often in infancy
2. Food allergy — can develop in the first 1-2 years; up to 35-40% of children with moderate-to-severe AD develop IgE-mediated food allergies
3. Asthma and allergic rhinitis — often emerge in later childhood

This progression is called the atopic march. It is important because it explains why eczema parents should be alert to signs of food allergy and respiratory symptoms, and why early-life interventions (such as structured early peanut introduction) have shifted from being discouraged to actively recommended in current guidelines. Not all children progress through every step, and having eczema does not guarantee later asthma.

Common signs in children

Children with eczema may have:

• dry, rough, or scaly patches
• red or darker inflamed skin (appearance varies with skin tone)
• itching, especially at night
• scratching that leads to broken skin
• oozing, crusting, or thickened skin during worse periods
• skin that looks different across body areas (face and cheeks in babies; elbows, knees, and creases in older children)

Sleep disruption is common and matters because tired children scratch more and cope less well. Sleep quality often tracks eczema severity more reliably than visual appearance alone.

Common myths

"There must be one exact trigger"

Not always. A child may flare because of a combination of dry skin, sweating, irritation, poor sleep, and a mild infection rather than one obvious exposure. Most flares are multi-factorial.

"If a product is natural, it is safe"

Not necessarily. Natural oils, herbs, or homemade treatments can still irritate skin or cause contact allergy. Coconut oil, for example, helps some children but worsens others. Essential oils are frequent irritants. "Organic" or "natural" baby products with long ingredient lists can be more problematic than simple petroleum jelly.

"Food causes eczema"

Usually not. While up to 35–40% of children with moderate-to-severe eczema develop food allergies, foods typically do not cause the eczema itself — the relationship primarily runs the other way (barrier disruption in early life facilitates food sensitisation through the skin). The 2025 AAP clinical practice guideline on atopic dermatitis emphasises that unnecessary elimination diets can cause nutritional harm in growing children and risk loss of tolerance to previously tolerated foods. If food allergy is suspected, structured evaluation with a clinician is much better than broad elimination on suspicion alone.

"If treatment helps, the diagnosis must be correct"

Not always. Some other skin problems can temporarily improve or worsen with eczema treatments. If the pattern is unusual or treatment keeps failing, the diagnosis may need to be reviewed.

"Steroid creams will thin my child's skin"

When used correctly at the right strength for the right duration, topical steroids do not cause skin thinning in children. Studies confirm this. The much bigger risk is undertreating eczema, which leads to worse flares, infection, and more suffering. See the section on steroid phobia for more detail.

The skin barrier in plain language

Think of healthy skin as a brick wall: skin cells are the bricks, and natural fats (ceramides, cholesterol, fatty acids) are the mortar. In eczema:

• The "mortar" is deficient, so water escapes (the skin dries out)
• Gaps in the wall let irritants and bacteria in
• The immune system overreacts to what gets through
• This triggers inflammation, which further damages the wall

This is why moisturisers work: they act as external "mortar" to temporarily seal the barrier. Products containing ceramides in a balanced lipid ratio (ceramides + cholesterol + free fatty acids, at roughly a 3:1:1 molar ratio) can be particularly helpful because they more closely mimic the natural lipid composition of healthy skin (Elias & Feingold, J Invest Dermatol, 2001; Chamlin et al., J Am Acad Dermatol, 2002).

Aqueous cream (crème aquatique) is not suitable as a leave-on moisturiser for eczema. It contains sodium lauryl sulphate (SLS), which damages the skin barrier and can worsen eczema in children. The NHS explicitly advises against its use as a leave-on emollient. Use it only as a soap substitute for washing if prescribed, not as a moisturiser.

When to rethink the pattern

Parents should ask for re-evaluation when:

• the rash keeps worsening despite careful treatment
• a product seems to make the skin consistently worse
• the distribution is unusual for eczema
• several family members are suddenly itchy (possible scabies)
• infection signs keep appearing
• the child fails to respond to 1-2 well-executed treatment cycles

Conditions that can sometimes be confused with eczema include:

Condition	Key differences from eczema
Allergic contact dermatitis	Unusual distribution; worsens with "treatment"; may relate to specific product ingredients
Scabies	Burrows visible; household contacts itchy; poor response to standard eczema therapy
Fungal infection (tinea)	Ring-shaped lesions; peripheral scale; resistant to steroid treatment
Psoriasis	Thicker, well-defined silvery plaques; different distribution
Seborrheic dermatitis	Greasy yellow scale; commonly scalp, eyebrows, behind ears

Key references

• Langan SM, Irvine AD, Weidinger S. "Atopic dermatitis." Lancet 396:345–360, 2020. — comprehensive review of pathophysiology and management.
• Palmer CN et al. "Common loss-of-function variants of the epidermal barrier protein filaggrin are a major predisposing factor for atopic dermatitis." Nature Genetics 38(4):441–6, 2006.
• Gallo RL, Horswill AR. "Staphylococcus aureus: The Bug Behind the Itch in Atopic Dermatitis." J Invest Dermatol 144(5):950–953, 2024.
• Bieber T. "Atopic dermatitis." New England Journal of Medicine 358(14):1483–94, 2008. — foundational review of Th2/Th22 immune mechanisms.
• Du Toit G et al. "Randomized trial of peanut consumption in infants at risk for peanut allergy (LEAP trial)." NEJM 372:803–813, 2015.
• AAP. "Atopic Dermatitis: Clinical Practice Guideline." Pediatrics, 2025.