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Types of food reactions

  • True food allergies: mediated by specific IgE against the specific food. This type of allergy is capable of triggering severe reactions (anaphylactic shock)
  • Oral Allergy Syndrome (OAS)
    • fruit-pollen OAS (best known : apple-birch tree): patients suffering from birch tree allergy may suffer from prurit and oedema in the mouth/throat, even going as far as an anaphylaxy, when their mucous membrane of the mouth is in contact with fresh fruit such as apples. Cause of this reaction is to be found in the similarity of pollens and fruits’ allergens (crossed reaction).
    • fruit-latex OAS: crossed reaction between latex and kiwis, bananas, avocados, etc. (see more in latex article)
  • Food intolerance: are not mediated by IgE. Intolerance to gluten or glucose is caused by deficit in digestive enzymes for instance.


Generally speaking, all foods can cause a rash. However, some are more allergenic than others: crustaceans, shellfish, some fish, umbelliferae (celery), peanuts, soy, dairy products (especially in children), eggs, some exotic fruits like pineapple, kiwi and avocado.

Symptoms range from simple itching in the mouth, vomiting, to severe anaphylactic reaction with urticaria-angioedema, breathing difficulty and shock (lowered blood pressure, fainting).


Diagnosis is based on anamnesis (patient’s history) due to the rapidity of the reaction. Diagnosis is then confirmed by skin prick-tests, IgE blood tests, and eventually an oral provocation test

Commercial extracts for skin testing are not well standardized (dubious quality), therefore our tests are prepared with fresh food.

Sometimes, the offending food is not easy to detect, for example, peanuts can be hidden in a salad dressing. This requires a more complex investigation.


  • strict avoidance of the allergen
  • always carry emergency kit and allergy passport 

Eviction: reading labels on processed foods is essential. If in doubt, or in the absence of such a list, it is better to abstain. Beware of the so-called “hidden food” (eg crushed peanuts in spaghetti sauce).

Emergency kit and allergy passport are useful in case the food is consumed inadvertently

Newborns and babies whose eczema worsens if they consume milk, a strict avoidance of milk must be carried out when starting on foods. Immune and digestive systems of the newborn gradually come to maturity. It will be possible to reintroduce the food under medical supervision at a later stage.

Prevention in infants

Breastfeeding is encouraged (should be preferred to bottles)

To prevent and detect at an early stage babies’ allergies, it is recommended to gradually introduce foods, one at a time. It is recommended to introduce fish only after the age of 2 ½ years, hazelnuts and almonds after 3 years and simply avoid peanuts.


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