Note from the National Guideline Clearinghouse (NGC): This guideline was developed by the Centre for Clinical Practice at the National Institute for Health and Clinical Excellence (NICE). See the "Availability of Companion Documents" field for the full version of this guidance.
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 the table below. Pay particular attention to persistent symptoms that involve different organ systems.
Table: Signs and Symptoms of Possible Food Allergy
|Immunoglobulin E (IgE)-Mediated
|Acute urticaria – localised or generalised
|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
||Loose or frequent stools
||Blood and/or mucus in stools
|Colicky abdominal pain
||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:
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 general practitioner [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 (see the first recommendation and the table above), 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, including the age at which they were weaned and whether they were breastfed or formula-fed – if the child is currently being breastfed, consider the mother's diet
- 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
- Signs indicating allergy-related comorbidities (atopic eczema, asthma and allergic rhinitis).
Food allergy can be classified into immunoglobulin E (IgE)-mediated and non-IgE-mediated allergy. IgE-mediated reactions are acute and frequently have a rapid onset. Non-IgE-mediated reactions are generally characterised by delayed and non-acute 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.
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 (see "Non-IgE-Mediated Food Allergy," above), 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.
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 the first recommendation and the table above
- 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
- 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 immunoglobulin G (IgG) testing in the diagnosis of food allergy.