Food allergies in children

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In this article

  • what are they
  • symptoms
  • allergenic foods
  • how to diagnose
  • therapies
  • what to do in case of involuntary ingestion of an allergenic food
  • prevention

What are food allergies

A food allergy occurs when the immune system it reacts abnormally and excessively to details proteins found in some foods, which are generally hired without problems by the majority of people. This abnormal reaction usually appears shortly after ingesting the food in question and can have varying degrees of severity, from mild to moderate to severe. 


Symptoms can affect different parts of the body:

  • disorders gastrointestinal, such as nausea and vomiting, diarrhea and abdominal pain (these are the most common)
  • disorders of the skin, such as hives or swelling (also quite common)
  • disorders respirators such as rhinitis and bronchial asthma (more rare)
  • disorders circulators such as paleness, weakness, loss of consciousness (also rare but potentially serious, are usually preceded by other symptoms)

There can also be a terrifying generalized reaction, involving various organs: it is anaphylactic shock, which requires prompt intervention because it can be fatal. 

Read also: Children's dermatitis, how to recognize and treat them

The causes: foods that cause allergies

In theory, any food is capable of causing allergic reactions, but only a minority of foods are responsible for the majority of food allergies. In particular, these are:

  • cow milk
  • eggs
  • soy
  • wheat
  • nuts (walnuts, pistachios, hazelnuts, Brazil nuts)
  • peanuts
  • fish (cod, tuna, salmon, trout, sole, etc.)
  • crustaceans and molluscs (shrimps, mussels, etc.)

In most cases, the allergy affects only one food, but there may be situations where an individual is allergic to two or more foods. 

How is the diagnosis made

Diagnosis is based on the combination of various elements:

Clinical history

The first step is the analysis of the child's medical history, collecting information on symptoms, on the time interval between food intake and the appearance of some abnormal manifestation, on familiarity due to allergies, etc.

Prick Test result

This is a skin test using a series of allergenic extracts which are placed at various points drop by drop. The skin will react by forming a small wheal when it comes in contact with the substance the baby is allergic to.

Growth test

It is a blood test that looks for total IgE antibodies or specific IgE antibodies against the suspect food

Elimination diet and trigger test

The decisive test to prove that the food is indeed the cause of the symptoms is its exclusion from the diet: in practice, the suspect food is completely eliminated from the diet for two to three weeks, and if at the end of this period the symptoms are still present, it means that the excluded foods are not involved in the onset of symptoms. 

If, on the other hand, these have disappeared or are reduced, the food will have to be introduced again in an equipped hospital environment (trigger test): if the symptoms reappear, this is the unequivocal proof of food allergy.

Read also: Allergies and children, the complete guide

How food allergies are treated

In case of certain food allergy, lTherapy consists simply in avoiding the allergen, that is, the food responsible for the reaction. Of course, that's easier said than done: many ingredients are almost omnipresent in packaged products and for children who have to give up certain foods while their friends and companions can safely eat them there can be added psychological burden. 

For this reason, in addition to the pediatrician allergist, it may also be useful to involve the figure of a nutritionist and possibly a psychologist. Sometimes it may also be necessary to take supplements for items that may be missing, such as calcium or iron. 

The path to desensitization: the allergy vaccine

Many food allergies pass on their own in the first few years of life. If this does not happen, after the sixth year a path of desensitize (we also speak of specific immunotherapy or allergy vaccine) for the offending food. 

In practice: in appropriately equipped hospitals, the child is given a certain amount of "critical" food, for example egg or milk. If there are no side effects, the child will need to take that precise amount of food every day at home until the next hospital appointment, when an attempt is made to increase the dose. It is a long process, which can take years, with very individual reactions: in some cases there will be the total disappearance of the symptoms, in others a more or less marked attenuation. 

Read also: Allergy vaccines: how specific immunotherapy works

What to do in case of accidental ingestion

Symptoms caused by inadvertent intake of the allergy-causing food can be mild, moderate, or severe. If several disorders appear at the same time (for example) urticaria, swelling, rhinitis, it is necessary to intervene with emergency therapy (adrenaline with self-injectable syringe, available as an emergency kit, antihistamine and cortisone) and take the child to the emergency room, because there may be risk of anaphylactic shock.

How to prevent

Unfortunately, there isn't much that can be done to prevent food allergies, which depend on a combination of genetic and environmental factors. However, some measures may be helpful in the sense that they appear to reduce the overall risk of allergies:

  • breastfeed
  • avoid smoking during pregnancy and in the presence of a child
  • ventilate the rooms well to reduce humidity which facilitates the proliferation of allergens (this more for respiratory allergies)

Sources for this article

  • Food Allergy, materiale informativo dell'American College of Allergy, Ashtma and Immunology
  • Food Allergies in Children, information material from the site, by American pediatricians
  • information material on the web page of the Bambino Gesù Pediatric Hospital

Questions and answers

How long can a food allergy last?

Food allergies very often disappear over time. Other times, however, they can last for a lifetime, especially in the case of a nut allergy.

Can potentially allergenic foods be introduced during weaning?

The answer is yes: contrary to what was thought in the past, today science tells us that delaying the introduction of potentially allergenic foods does not reduce the risk of children developing those allergies.

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