Food Allergy

Food Allergy 

  • General points – The most common food allergens for children are milk, egg, peanut, tree nuts, soy, fish, shellfish, wheat, kiwi fruit and sesame
  • Further guidance for milk and egg allergy are given below as these are relatively common food allergies with distinctive natural histories
  • Take an allergy-focused history, noting -
  • Speed of onset of symptoms following contact with suspected food (reactions after 2 hours extremely unlikely to be IgE mediated)
  • Which food(s) ingested, and how much of that food caused the reaction?
  • Symptoms and signs in relation to the food exposure, always note

severity – particularly whether airway or circulation involved (anaphylaxis). Often a dose – response relationship, but can be unpredictable, subsequent reactions not always worse

  • Whether reaction has been reproducible (has child had that food since with no reaction – if they have they are not allergic to that food)
  • Feeding history, including whether breast or formula fed / weaning and any timings of feed changes vs symptoms
  • Allergic co-morbidities (esp. asthma, eczema, rhinitis) present?
  • Family history of current / past atopy –

But family history of food allergy is not an indication for referral

 Based on history, decide which type of allergy you suspect –

IgE – mediated or non-IgE mediated


  • IgE-mediated symptomshave acute onset (usually minutes to not more than 2 - 4hrs post exposure) and include one or a combination of urticaria, angioedema, rhino-conjunctivitis, wheeze, stridor, repetitive and copious vomiting, collapse

  Any airway involvement or circulatory compromise = anaphylaxis even if no rash

Refer any child who has had a significant IgE-mediated reaction to a small amount of food, or anaphylaxis


  • Non-IgE-mediated symptomshave delayed/non-acute onset and  include exacerbation of atopic eczema, worsening of gastro – oesophageal reflux or reproducible abdominal upset (vomiting, loose stools) after that food
  • Reassure parents that not a dangerous allergy
  • Try a trial of elimination of suspected allergen for 2-4 weeks
  • If child does not improve, allergy unlikely; treat for the reflux / constipation / eczema bearing in mind commonality of these conditions without food allergy being presen, and re-introduce the food
  • For a diagnosis and treatment plan specific to non – IgE milk allergy, see section on milk below.
  • If child does improve then worsens on re-introduction of food, make the diagnosis and advise avoidance. Paediatric dietitian referral recommended if doubt about nutritional adequacies of diet or timings of food re-introduction
  • Consultant – led Paediatric allergy clinic referral if child has faltering growth on serial weights (rare) or multiple foods responsible on trial elimination / re-introduction

Differential diagnosis of food allergy


IgE – mediated

Chronic spontaneous urticaria – itchy urticarial rash, not always related to food, but acidic foods can also flare this condition. Some 10-40% have angioedema too. See separate section.


Non IgE – mediated

Gastro-oesphageal reflux

Constipation (Idiopathic)

Chronic diarrhoea (consider Toddler Diarrhoea)

Lactose intolerance (see separate section)

Eczema, not food – related



Guideline updated by Simon Bedwani, Consultant Paediatrician, Royal Cornwall Hospital, November 2018.


Review Date                14/08/2019

Next Review Date        14/08/2020

GP Sifter                      Dr Rebecca Harling



Version No. 2.1