Child Allergy — Food Allergies, Eczema & Allergic Conditions in Children — Symptoms, Causes & Treatment | MyMedicPlus

Allergies in children are immune system reactions to normally harmless substances (allergens). The 'atopic march' describes the typical progression in allergic children: atopic dermatitis (eczema) in infancy, food allergy in early childhood, followed by allergic rhinitis and asthma. Allergic conditions affect 30-40% of children globally, making them among the most common chronic childhood diseases. Food allergy affects 6-8% of children under 5 years (declining with age). The most common food allergens in children are milk, eggs, peanuts, tree nuts, wheat, soy, fish, and shellfish. The 'atopic march' — eczema in infancy progressing to food allergy, then allergic rhinitis, then asthma — reflects a shared underlying immune dysregulation rather than separate independent conditions. Prevention and early intervention in eczema may therefore reduce the subsequent risk of food allergy and asthma in genetically predisposed children. The incidence of paediatric allergic disease has doubled in the past 30 years in high-income countries, attributed to increased urban living, reduced microbial diversity, and changing dietary patterns — a global trend that demands updated clinical guidelines on early allergen introduction and environmental management.

Allergy risk in children is significantly increased by: family history of atopy (eczema, asthma, or food allergy in parents or siblings); male sex (higher rates of food allergy in early childhood); urban environment; early antibiotic use disrupting the gut microbiome; delayed introduction of allergenic foods (early introduction of peanut protein in infants reduces peanut allergy risk by 70-80% — LEAP trial); Caesarean section birth and reduced microbial exposure; exclusive formula feeding (breastfeeding is protective); vitamin D deficiency; and exposure to environmental tobacco smoke. The 'hygiene hypothesis' suggests reduced childhood infection exposure increases allergic disease. Skin barrier gene mutations, particularly FLG (filaggrin), are the single strongest genetic risk factor for atopic eczema — present in 30% of eczema patients — and also predispose to food allergy by allowing allergen sensitisation through disrupted skin rather than via the gut.

Food allergy in children: reactions typically occur within minutes to 2 hours of ingesting the allergen. Symptoms range from mild (hives/urticaria, itchy mouth, runny nose) to severe anaphylaxis (throat swelling causing stridor, severe breathlessness, collapse, and loss of consciousness — a medical emergency requiring immediate adrenaline injection). Atopic dermatitis (eczema): dry, itchy, inflamed skin — typically on cheeks, flexural creases (elbows, behind knees), and wrists. Allergic rhinitis: sneezing, itchy/runny nose, blocked nose, and itchy eyes. Asthma: cough (especially at night), wheeze, and breathlessness triggered by allergens, exercise, or respiratory infections. Contact urticaria (immediate hive-like reaction to skin contact with allergen — e.g., latex, cat dander, raw fruit) must be distinguished from true systemic IgE-mediated food allergy. Oral allergy syndrome (pollen-food allergy syndrome) causes itching and swelling in the mouth when eating raw fruit and vegetables cross-reactive with pollen — typically mild and does not indicate risk of systemic anaphylaxis.

Clinical history is the cornerstone: type of food/exposure, timing and nature of reaction, reproducibility, and any risk factors. Skin prick testing (SPT): small amounts of allergen extracts are applied to the forearm and the skin is pricked through the extract; a raised wheal (bump) indicates sensitisation. Specific IgE blood tests (RAST/ImmunoCAP): measure allergen-specific IgE antibodies; component-resolved diagnosis (CRD) identifies specific protein components to refine risk. Atopy patch testing for non-IgE-mediated food allergies. Oral food challenge (OFC): the gold standard for food allergy diagnosis — controlled supervised introduction of the food in escalating doses. Spirometry for children with suspected asthma. Referral to a paediatric allergist is recommended for anaphylaxis history, multiple food allergies, or complex presentations.

Food allergy: strict avoidance of the identified allergen remains the cornerstone. All children with confirmed food allergy or anaphylaxis risk should carry an adrenaline (epinephrine) auto-injector (EpiPen or Jext) and parents and carers must be trained in its use. Oral immunotherapy (OIT) for peanut allergy is now licensed (Palforzia) in children aged 4-17 — desensitises by gradually increasing peanut protein doses, reducing anaphylaxis risk from accidental exposure. Eczema (atopic dermatitis): regular emollient moisturisers (apply generously, 2-3x daily); topical corticosteroids for flares (mild hydrocortisone for face; moderate-potent for body); topical calcineurin inhibitors (tacrolimus, pimecrolimus) for sensitive areas; dupilumab (biologics) for severe refractory eczema in children aged 6+. Allergic rhinitis: non-sedating antihistamines (cetirizine, loratadine); intranasal corticosteroids. Allergen immunotherapy (sublingual or subcutaneous) for grass pollen or house dust mite allergy.

Anaphylaxis untreated leads to respiratory failure, cardiovascular collapse, and death within minutes — adrenaline must be administered immediately. Uncontrolled eczema causes sleep deprivation from itching (affecting 60-80% of children with atopic dermatitis), increased skin infection risk (Staphylococcus aureus colonises 90% of eczema skin and can cause impetiginisation), and significant impact on school performance and quality of life for child and family. Undiagnosed food allergy in school-age children risks accidental exposure and potentially fatal anaphylaxis in school settings. Severe, uncontrolled allergic disease in childhood may lead to persistent asthma and reduced lung function in adulthood.

Early introduction of allergenic foods (peanut butter, eggs, wheat) in infants aged 4-6 months who have eczema or egg allergy reduces the chance of developing food allergy (LEAP trial: 70-80% reduction in peanut allergy). Breastfeed for at least 4-6 months where possible. Do not smoke around children or during pregnancy. Create an allergen-free environment: house dust mite reduction (allergen-proof mattress covers, washing bedding at 60 degrees Celsius weekly), avoid known pet allergens in sensitised children. Provide schools and carers with an individualised Allergy Action Plan, spare EpiPen, and training. Seek regular review with a paediatric allergist as many food allergies (milk, egg, soy, wheat) are outgrown by school age — do not maintain unnecessary restrictions.

Call 999 (or emergency services) immediately if your child shows signs of anaphylaxis: throat swelling or hoarse voice (stridor), severe difficulty breathing or wheezing not relieved by an inhaler, collapse or loss of consciousness, pale or blue lips, or widespread hives combined with vomiting or sudden severe weakness. Administer the adrenaline auto-injector (EpiPen) immediately — do not wait for symptoms to worsen — then call 999. Take your child to A&E or see a doctor urgently if: a suspected allergic reaction causes vomiting, dizziness, or extensive swelling without breathing difficulty; eczema becomes infected (weeping, crusted, very red, or the child has a fever); the child has difficulty breathing associated with suspected allergic asthma. See your GP for non-urgent referral to a paediatric allergist if: your child has had any allergic reaction to food; eczema is difficult to control with standard emollients and mild topical steroids; you suspect a new food allergy or multiple food allergies; or you need guidance on introducing allergenic foods in a high-risk infant. All children diagnosed with food allergy should be reviewed by a paediatric allergist at least annually to reassess whether the allergy has been outgrown.