Food Allergy
Reproducible adverse immune reaction to a specific food protein, ranging from mild to anaphylactic.
Overview
True food allergy affects ~6–8% of children and 2–3% of adults. IgE-mediated reactions occur within minutes to 2 hours and can cause anaphylaxis. Non-IgE-mediated reactions cause delayed gastrointestinal or skin symptoms. Cow's milk, egg, peanut, tree nut, soy, wheat, fish, shellfish and sesame account for most reactions.
Symptoms
- • Hives, angioedema, itch within minutes to 2 hours of food
- • Vomiting, abdominal pain, diarrhoea
- • Wheeze, throat tightness, hoarse voice
- • Hypotension, collapse — anaphylaxis
- • Eczema flare or chronic diarrhoea in non-IgE forms
Risk factors
- • Personal or family atopy
- • Eczema in infancy (especially severe)
- • Delayed introduction of allergens in infancy
Causes
- • IgE-mediated: peanut, tree nut, milk, egg, shellfish, fish, sesame, wheat, soy
- • Non-IgE-mediated: FPIES, allergic proctocolitis, eosinophilic oesophagitis
- • Pollen–food syndrome (oral allergy) with raw fruits and vegetables
🚨 Red flags — seek urgent care
- • Airway swelling, wheeze, hypotension — anaphylaxis: adrenaline now
- • Repeated severe reactions
- • Reactions to trace exposure
When to seek care
- • Suspected reproducible reaction to a specific food
- • Any reaction with breathing difficulty, throat or facial swelling
- • Children with severe eczema and suspected food trigger
Diagnosis
- • Detailed allergy-focused clinical history is the cornerstone
- • Skin-prick testing and/or specific IgE — interpret with clinical context (sensitisation ≠ allergy)
- • Oral food challenge in specialist allergy clinic when diagnosis uncertain
- • Component-resolved diagnostics for nut and shellfish allergies
- • Do NOT use unvalidated tests (IgG, hair analysis, kinesiology)
Treatment
- • Strict avoidance of the implicated allergen
- • Adrenaline auto-injector × 2 prescribed for any history of anaphylaxis or risk features
- • Antihistamine for mild reactions only
- • Written personalised emergency action plan; staff training in schools
- • Oral immunotherapy (peanut, milk, egg) in specialist centres for selected children
Prevention
- • Early introduction of peanut and egg from 4–6 months (LEAP/EAT evidence)
- • Optimise eczema management in infancy
- • Read food labels; alert restaurants
Complications
- • Anaphylaxis with fatal outcome (rare but preventable)
- • Nutritional deficiency from over-restriction
- • Anxiety, social isolation, reduced quality of life
Prognosis
Milk and egg allergies usually resolve in childhood; peanut, tree nut, fish, shellfish often persist into adulthood.
Education & self-care
Food allergy is serious but very manageable with the right diagnosis, written action plan and access to adrenaline. Avoid unproven tests — they cause unnecessary restriction.
Frequently asked questions
Are food intolerances the same as allergies?
No. Intolerances (e.g. lactose) involve digestion, not the immune system, and don't cause anaphylaxis.
Can my child outgrow peanut allergy?
Around 20% do, but resolution should only be confirmed by a specialist with allergy testing or supervised challenge.
How is a true food allergy diagnosed?
A clear history of reproducible reactions within minutes to hours of a specific food, supported by skin-prick tests, specific IgE blood tests, and, where uncertain, a supervised oral food challenge.
Are food intolerances the same as allergies?
No. Intolerances (e.g. lactose) are not immune-mediated and do not cause anaphylaxis. IgE tests are not useful for them, and broad 'food sensitivity' panels are not recommended.
Can a child outgrow a food allergy?
Milk and egg allergies often resolve by school age. Peanut, tree-nut, fish and shellfish allergies more commonly persist into adulthood, but specialist immunotherapy is an option for some.