Food Allergy

Association, mostly; cause, sometimes. Food allergy and Atopic Dermatitis travel together in infancy and the toddler years, and both have been linked to an impaired skin barrier. Current evidence suggests the arrow mainly runs from eczema to food allergy rather than the other way round: raised water loss through the skin and early eczema usually come before food sensitisation (Papapostolou 2022), which fits the Dual-Allergen Exposure Hypothesis. A 2025 JACI: In Practice review says IgE “has a marginal role in most patients” with AD, but that the faulty skin barrier puts them at greater risk of developing food allergy (Braun et al. 2025). In a minority of young children, a food does make the eczema worse (“food-triggered AD”). This happens either through immediate IgE reactions (hives, swelling, vomiting within about 2 hours) or through delayed eczema flares 6–48 hours after eating (Chang et al. 2016).

Skin Barrier Dysfunction [causes] Food Allergy Atopic Dermatitis [precedes] Food Allergy Food Allergy [worsens] Atopic Dermatitis Food Allergy [relates] Th2 Immune Response

How common is it in children with moderate–severe eczema? Foods are a proven trigger in about 20–30% of moderate-to-severe childhood AD. Food triggers matter more in children under 5, while airborne allergens matter more in older children and adults (Chang et al. 2016, citing earlier challenge studies). A 2024 review puts the overall figure at about 40% of AD patients having food allergy (Medicina 2024). In a US tertiary allergy clinic, 298 children (mean age 1.8 years) were referred for “food-triggered eczema”. Allergists judged 61% to have probable food-triggered AD, 32% to have an unclear link and 6% to have eczema unrelated to food. Milk (57%), egg (31%) and soy (21%) were the foods most often blamed (Chang et al. 2016). This was a referred, selected group, so these figures are higher than in the general toddler population. Most toddlers with mild eczema have no relevant food allergy.

Conflict: [Chang et al., JACI Pract, 2016] says foods trigger ~20–30% of moderate–severe childhood AD. [Medicina review, 2024] says ~40% of AD patients have food allergy, and [Kohl, 2026, cited in Herbal and Home Remedies for Eczema] says 30–40% of children with moderate-to-severe AD have IgE-mediated food allergy. [Braun et al., JACI Pract, 2025] says IgE has “a marginal role in most patients”. The figures may measure different things (proven trigger vs any co-existing allergy vs sensitisation). Unresolved — add to open_questions.

Food Allergy [relates] Atopic Dermatitis Food Allergy [part-of] Atopic March

When to suspect it (NICE CG57). NICE CG57 (rec 1.4.1.2) advises considering food allergy only in: (a) children with eczema who have had immediate symptoms after eating a particular food; or (b) babies and young children with moderate or severe eczema that has not been controlled by optimum management, especially with gut problems (colic, vomiting, altered bowel habit) or faltering growth. NICE tells parents that most children with mild eczema do not need allergy tests (1.4.1.5). It advises against high-street or internet allergy tests (1.4.1.6). It recommends referral for specialist investigation when moderate or severe eczema comes with suspected food allergy (1.10). For bottle-fed babies under 6 months with uncontrolled moderate–severe eczema, NICE recommends offering a 6–8 week trial of extensively hydrolysed or amino-acid formula. It also advises against goat’s or sheep’s milk and partially hydrolysed formulas (1.4.1.7–1.4.1.9). The 2010 NIAID guideline, summarised by the American Academy of Dermatology, is similar. It suggests evaluating children under 5 with moderate–severe AD for milk, egg, peanut, wheat and soy allergy only if the AD persists despite optimised treatment, or if there is a reliable history of an immediate reaction.

NICE CG57 [regulates] Food Allergy American Academy of Dermatology [regulates] Food Allergy Food Allergy [relates] Oral Food Challenge

Testing pitfalls: sensitisation is not allergy. Children with eczema often have high total IgE. As a result, Skin Prick Testing and blood specific-IgE tests often come back “positive” to foods the child eats without any problem. Their positive predictive value is low, so guidance says to test only when there is a matching immediate reaction such as hives or angioedema, not for eczema alone (Braun et al. 2025; Chang et al. 2016). The NIAID 2017 expert panel “does not recommend food allergen panel testing” because of poor positive predictive value, “which could lead to misinterpretation, over diagnosis of food allergy, and unnecessary dietary restrictions” (Togias et al. 2017). Skin prick tests alone cannot diagnose food allergy, and intradermal tests should not be used (NIAID 2010 via AAD). The reference standard is a supervised Oral Food Challenge. The 2022 AAAAI/ACAAI Joint Task Force review found no credible difference in outcome between test-guided and empiric elimination (Oykhman et al. 2022). In other words, a positive test did not identify the children who would benefit from cutting a food out.

Skin Prick Testing [relates] Food Allergy Oral Food Challenge [defines] Food Allergy Food Allergy [relates] Elimination Diets

What this means for parents. Most experts now aim to “control AD while retaining these foods in the diet” (Braun et al. 2025). Cutting foods out on the strength of a positive test, or on suspicion alone, risks new and sometimes severe IgE allergy and nutritional harm (see Elimination Diets). Eating allergenic foods early helps build tolerance (see LEAP Trial, EAT Trial). Parents online often frame food as the “root cause”. The commonest replies in parent threads, including from parents whose children have confirmed allergies, are “treat the eczema first” and “eczema likely causes food allergies, not the other way round” (Reddit r/moderatelygranolamoms, r/BabyLedWeaning; evidence: anecdotal). Some parents do report clear egg- or dairy-linked flares, which then faded by around age 1–2 (evidence: anecdotal).

Elimination Diets [causes] Food Allergy Emollient Therapy [relates] Food Allergy

Connections

• Emollient Therapy — infant emollient use may raise risk, source: Cochrane 2022
• Atopic Dermatitis — co-occurs in infancy; first step of the atopic march; ~40% of AD patients have food allergy per some reviews, source: Medicina 2024
• Skin Barrier Dysfunction — raised TEWL and eczema usually precede food allergy; AD predisposes to FA rather than vice versa, source: Papapostolou, J Clin Med 2022
• Dual-Allergen Exposure Hypothesis — skin exposure sensitises, early oral exposure tolerises, source: Papapostolou 2022
• Th2 Immune Response — IgE sensitisation via Th2 cells, source: Papapostolou 2022
• Herbal and Home Remedies for Eczema — peanut-oil skin creams linked to peanut allergy; elimination diets can create new allergy, source: Lack 2003; Kohl 2026
• Colloidal Oatmeal — percutaneous oat sensitisation in AD children (APT+ 32% of oat-cream users vs 0%), source: Boussault 2007
• NICE CG57 — recs 1.4.1.2–1.4.1.11: when to suspect food allergy, no routine/high-street testing, formula trials, source: NICE CG57
• Skin Prick Testing — low positive predictive value in AD; test only with concordant immediate reaction, source: Braun 2025; NIAID 2017
• Oral Food Challenge — diagnostic reference standard, source: Chang 2016; NIAID 2017
• Elimination Diets — slight benefit at best; can create new IgE allergy (19%), source: Oykhman 2022; Chang 2016
• American Academy of Dermatology — summarises NIAID: evaluate only if AD uncontrolled or immediate reaction, source: AAD
• LEAP Trial — early peanut feeding prevents peanut allergy in eczema infants, source: Du Toit 2015
• EAT Trial — early multi-allergen introduction; per-protocol benefit, source: Perkin 2016
• Atopic March — food allergy is an early step, source: Medicina 2024
• Dupilumab — lowers food-specific IgE but no proven tolerance, source: Grześk-Kaczyńska IJMS 2026
• Tree Nut Allergy — 3.3% challenge-confirmed by age 6 in HealthNuts, source: McWilliam 2019
• When to Refer — allergy referral criteria, source: NICE CG57; AAD/NIAID
• BEEP Trial — infant emollients did not cut food allergy by age 5 (15% vs 14%), source: Bradshaw, Allergy 2023