Food allergy is an adverse immune response to a food. It can be classified into IgE-mediated and non-IgE-mediated reactions. The starting point for the guideline is a suspicion of food allergy, and the use of an allergy-focused clinical history will help to determine whether a food allergy is likely.
This guideline is the basis of NICE Quality Standard 118.
Assessment and Allergy-focused Clinical History
- Consider the possibility of food allergy in children and young people who have one or more of the signs and symptoms in Table 1, below. Pay particular attention to persistent symptoms that involve different organ systems.
Table 1: Signs and Symptoms of Possible Food Allergy
|Acute urticaria—localised or generalised||Atopic eczema|
|Acute angioedema—most commonly of the lips, face and around the eyes|
|The gastrointestinal system|
|Angioedema of the lips, tongue and palate||Gastro-oesophageal reflux disease|
|Oral pruritus||Loose or frequent stools|
|Nausea||Blood and/or mucus in stools|
|Colicky abdominal pain||Abdominal pain|
|Diarrhoea||Food refusal or aversion|
|Pallor and tiredness|
|Faltering growth in conjunction with at least 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)|
|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)|
|Signs or symptoms of anaphylaxis or other systemic allergic reactions|
|Note: this list is not exhaustive. The absence of these symptoms does not exclude food allergy|
- Consider the possibility of food allergy in children and young people whose symptoms do not respond adequately to treatment for:
- atopic eczema[A]
- gastro-oesophageal reflux disease (for information about gastro-oesophageal reflux disease see NICE’s guideline on gastro-oesophageal reflux disease in children and young people: diagnosis and management)
- chronic gastrointestinal symptoms, including chronic constipation.Someone with apparent symptoms of food allergy may be suffering from coeliac disease; for information about coeliac disease, see NICE’s guideline on coeliac disease: recognition, assessment and management.
- If food allergy is suspected (by a healthcare professional or the parent, carer, child or young person), a healthcare professional with the appropriate competencies (either a GP or other healthcare professional) should take an allergy-focused clinical history tailored to the presenting symptoms and age of the child or young person. This should include:
- any personal history of atopic disease (asthma, eczema or allergic rhinitis)
- any individual and family history of atopic disease (such as asthma, eczema or allergic rhinitis) or food allergy in parents or siblings
- details of any foods that are avoided and the reasons why
- an assessment of presenting symptoms and other symptoms that may be associated with food allergy, including questions about:
- the age of the child or young person when symptoms first started
- speed of onset of symptoms following food contact
- duration of symptoms
- severity of reaction
- frequency of occurrence
- 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 foods they eat
- who has raised the concern and suspects the food allergy
- what the suspected allergen is
- the child or young person’s feeding history, whether they were breastfed or formula-fed and the age of weaning
- the mother’s diet, if the child is currently being breastfed
- details of any previous treatment, including medication, for the presenting symptoms and the response to this
- any response to the elimination and reintroduction of foods.
- Based on the findings of the allergy-focused clinical history, physically examine the child or young person, paying particular attention to:
- growth and physical signs of malnutrition (for information about faltering growth see NICE’s guideline on faltering growth: recognition and management of faltering growth in children)
- signs indicating allergy-related comorbidities (atopic eczema, asthma and allergic rhinitis).
- Food allergy can be classified into IgE-mediated and non-IgE-mediated allergy. IgE-mediated reactions are often immediate and frequently have a rapid onset. Non-IgE-mediated reactions are generally characterised by delayed reactions.
IgE-mediated Food Allergy
- Based on the results of the allergy-focused clinical history, if IgE-mediated allergy is suspected, offer the child or young person a skin prick test and/or blood tests for specific IgE antibodies to the suspected foods and likely co-allergens
- Tests should only be undertaken by healthcare professionals with the appropriate competencies to select, perform and interpret them.
- Skin prick tests should only be undertaken where there are facilities to deal with an anaphylactic reaction.
- Choose between a skin prick test and a specific IgE antibody blood test based on:
- the results of the allergy-focused clinical history and
- whether the test is suitable for, safe for and acceptable to the child or young person (or their parent or carer) and
- the available competencies of the healthcare professional to undertake the test and interpret the results.
- Do not carry out allergy testing without first taking an allergy-focused clinical history. Interpret the results of tests in the context of information from the allergy-focused clinical history.
- Do not use atopy patch testing or oral food challenges to diagnose IgE-mediated food allergy in primary care or community settings.
Non-IgE-mediated Food Allergy
- Based on the results of the allergy-focused clinical history, if non-IgE-mediated food allergy is suspected, trial elimination of the suspected allergen (normally for between 2–6 weeks) and reintroduce after the trial. Seek advice from a dietitian with appropriate competencies, about nutritional adequacies, timings of elimination and reintroduction, and follow-up. (For people undergoing investigation for coeliac disease see NICE’s guideline on coeliac disease: recognition, assessment and management.)
Providing Information and Support to the Child or Young Person and their Parent or Carer
- Based on the allergy-focused clinical history, offer the child or young person and their parent or carer, information that is age-appropriate about the:
- type of allergy suspected
- risk of severe allergic reaction
- potential impact of the suspected allergy on other healthcare issues, including vaccination
- diagnostic process, which may include:
- an elimination diet followed by a possible planned rechallenge or initial food reintroduction procedure
- skin prick tests and specific IgE antibody testing, including the safety and limitations of these tests
- referral to secondary or specialist care.
- Offer the child or young person and their parent or carer, information that is relevant to the type of allergy (IgE-mediated, non-IgE-mediated or mixed).
- If a food elimination diet is advised as part of the diagnostic process, offer the child or young person and their parent or carer, taking into account socioeconomic status and cultural and religious issues, information on:
- what foods and drinks to avoid
- how to interpret food labels
- alternative sources of nutrition to ensure adequate nutritional intake
- the safety and limitations of an elimination diet
- the proposed duration of the elimination diet
- when, where and how an oral food challenge or food reintroduction procedure may be undertaken
- the safety and limitations of the oral food challenge or food reintroduction procedure.
- For babies and young children with suspected allergy to cows’ milk protein, offer:
- food avoidance advice to breastfeeding mothers
- information on the most appropriate hypoallergenic formula or milk substitute to mothers of formula-fed babies.Seek advice from a dietitian with appropriate competencies.
- Offer the child or young person, or their parent or carer, information about the support available and details of how to contact support groups. (See the information for the public on the NICE website for examples of organisations that provide information and support.)
Referral to Secondary or Specialist Care
- Based on the allergy-focused clinical history, consider referral to secondary or specialist care in any of the following circumstances.
- The child or young person has:
- faltering growth in combination with one or more of the gastrointestinal symptoms described in Table 1
- not responded to a single-allergen elimination diet
- had one or more acute systemic reactions
- had one or more severe delayed reactions
- confirmed IgE-mediated food allergy and concurrent asthma
- significant atopic eczema where multiple or cross-reactive food allergies are suspected by the parent or carer.
- The child or young person has:
- There is:
- persisting parental suspicion of food allergy (especially in children or young people with difficult or perplexing symptoms) despite a lack of supporting history
- strong clinical suspicion of IgE-mediated food allergy but allergy test results are negative
- clinical suspicion of multiple food allergies.
Alternative Diagnostic Tools
- Do not use the following alternative diagnostic tests in the diagnosis of food allergy:
- vega test
- applied kinesiology
- hair analysis.
- Do not use serum-specific IgG testing in the diagnosis of food allergy.
[A] For information about treatment for atopic eczema see NICE’s guideline on atopic eczema in under 12s: diagnosis and management.