Investigations

Key Messages:

• Clinical history is an essential part of the diagnosis pathway for all cases of suspected food allergy
• Good first-line tests for IgE-mediated food allergy include skin prick tests and specific IgE blood tests
• Testing should be focused on the foods reported to cause symptoms
• Individuals who are pollen sensitised can have positive tests to pollen-related foods such as nuts, which may not be indicative of an allergy to peanuts or tree nuts
• Testing for individual allergens using component-resolved diagnostics is useful in pollen sensitised individuals, those with suspected co-factor induced allergy, and to assess the likelihood of resolution to milk or egg
• There are no validated tests for non-IgE-mediated allergy or non-immune-mediated food hypersensitivity, so a supervised 6-8 week exclusion of the suspected food(s) may be necessary
• Oral food challenges are the gold standard diagnostic test for food allergy

NICE guidance on the diagnosis of food allergy in children and young people gives a good overview of the diagnosis pathway for suspected food allergy. 

• https://www.rcpch.ac.uk/resources/allergy-care-pathway-food-allergy
• https://www.nice.org.uk/guidance/cg116

More recently, a quality standard has also been produced (NICE 2016).

• https://www.nice.org.uk/guidance/qs118

Unfortunately, there is no such standard or guideline specifically for adult-onset food allergy.