Testing for food allergy
Alternative diagnostic tools not recommended.
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 to diagnose food allergy.
Testing for IgE-mediated food allergy: skin prick test for specific IgE antibodies
Offer a skin prick test and/or blood tests for specific IgE antibodies to the suspected foods and likely co-allergens.
Base choice of test on:
- the clinical history and
- the suitability, safety for, and acceptability 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
Tests should only be undertaken by healthcare professionals with the appropriate competencies to select, perform and interpret them.
Only undertake skin prick tests where there are facilities to deal with an anaphylactic reaction.
Interpret test results in the context of clinical history.
Do not use atopy patch testing or oral food challenges to diagnose IgE-mediated allergy in primary care or community settings.
Testing for non-IgE-mediated food allergy: elimination test
Try eliminating the suspected allergen (normally for between 2-6 weeks), then reintroduce. Seek advice from a dietitian with appropriate competencies about nutritional adequacies, timings of elimination and reintroduction, and follow-up.
Taking into account socioeconomic, cultural and religious issues, offer information on:
- what foods and drinks to avoid
- how to interpret food labels
- alternative sources of nutrition to ensure adequate nutritional intake
- the duration, safety and limitations of an elimination diet
- oral food challenge or reintroduction procedures, if appropriate, and their safety and limitations
If allergy to cow’s milk protein is suspected, offer:
- food avoidance advice to breastfeeding mothers
- information on appropriate hypoallergenic formula or milk substitute to mothers of formula-fed babies
Seek advice from a dietitian with appropriate competencies.
Consider 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 signs and symptoms of possible food allergy
- 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