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Food allergy in under 19s: assessment and diagnosis


  • Food allergy is an adverse immune response to a food
  • Food allergy is one of the most common allergic disorders and is recognised as a major paediatric problem in western countries. Its prevalence has increased dramatically in recent decades
  • There is great variation in current practice for allergy care, and there are no agreed treatment pathways or referral criteria. Many people use alternative sources of support instead of NHS services, including non-validated tests and treatments

Key to terms

  • Food allergy can be classified into IgE-mediated and non-IgE-mediated allergy
  • IgE-mediated reactions are acute and often have a rapid onset
  • Non-IgE-mediated reactions are generally characterised by a delayed and non-acute onset
  • Mixed reactions involve a mixture of both IgE and non-IgE responses

Signs and symptoms of possible food allergy*

The skin

  • IgE-mediated
    • pruritus
    • erythema
    • acute urticaria (localised or generalised)
    • acute angioedema (most commonly in the lips and face, and around the eyes)
  • Non-IgE-mediated
    • pruritus
    • erythema
    • atopic eczema

The gastrointestinal system

  • IgE-mediated
    • angioedema of the lips, tongue and palate
    • oral pruritus
    • nausea
    • colicky abdominal pain
    • vomiting
    • diarrhoea
  • Non-IgE-mediated
    • gastro-oesophageal reflux disease
    • loose or frequent stools
    • blood and/or mucus in stools
    • abdominal pain
    • infantile colic
    • food refusal or aversion
    • constipation
    • perianal redness
    • pallor and tiredness
    • faltering growth plus one or more gastrointestinal symptoms above (with or without significant atopic eczema)

The respiratory system (usually in combination with one or more of the above symptoms and signs)

  • IgE-mediated
    • upper respiratory tract symptoms—nasal itching, sneezing, rhinorrhoea or congestion (with or without conjunctivitis)
    • lower respiratory tract symptoms (cough, chest tightness, wheezing or shortness of breath)
  • Non-IgE-mediated
    • lower respiratory tract symptoms (cough, chest tightness, wheezing or shortness of breath)


  • IgE-mediated
    • signs or symptoms of anaphylaxis or other systemic allergic reactions

Allergy-focused clinical history

  • Ask about:
    • any personal history of atopic disease (asthma, eczema or allergic rhinitis)
    • any individual and family history of atopic disease (asthma, eczema or allergic rhinitis) or food allergy in parents or siblings
    • details of any foods that are avoided and why
    • presenting symptoms and other symptoms that may be associated with food allergy (see ‘Signs and symptoms of possible food allergy’), including:
      • age at first onset
      • speed of onset
      • duration, severity and frequency
      • setting of reaction (for example, at school or home)
      • reproducibility of symptoms on repeated exposure
      • what food and how much exposure to it causes a reaction
    • cultural and religious factors that affect the child’s diet
    • who has raised the concern and suspects the food allergy
    • what the suspected allergen is
    • the child’s feeding history, including age of weaning and whether they were breastfed or formula-fed (if the child is breastfed, consider the mother’s diet)
    • details of previous treatment, including medication, for the presenting symptoms, and the response to this
    • any response to the elimination and reintroduction of foods

Allergy-focused clinical history

full guideline available from…
National Institute for Health and Care Excellence, Level 1A, City Tower, Piccadilly Plaza, Manchester, M1 4BT

National Institute for Health and Care Excellence. Food allergy in under 19s: assessment and diagnosis. February 2011
First included: February 2011.