It is important to make a distinction between allergy and food intolerance.
Food allergies act the same way other allergies do: a first phase of sensitisation, followed by a second phase of allergic reaction caused by contact with the allergen.

Intolerance is an adverse reaction or a hypersensitivity to some substances ingested.
In allergies immunoglobulins play a key role, while T lymphocytes are involved in   intolerance.
Depending on the kind of intolerance, it is possible that a small quantity of non tolerated food can be assumed by a subject without a reaction being triggered. On the contrary, if the issue is food allergy, even a tiny amount of food may trigger an allergic reaction.
Food allergies can cause severe symptoms and even anaphylactic shock.
Most frequent allergens are some kind of proteins contained in:

  • Shellfish
  • PeanutsNuts
  • Milk
  • Eggs
  • Fish

Many patients suffering from allergic rhinitis may be severely affected by fresh fruit and vegetables, as well as certain types of nuts and spices. An allergic reaction may include  typical symptoms as itching and tingling mouth.
In some patients, an allergic syndrome of this type, also called oral allergy syndrome (OAS), may cause swelling of the throat and anaphylactic shock. OAS is an example of cross-reactivity. The proteins found in fruit and vegetables can cause a reaction because they are very similar to those found in certain pollens.
Cooking fruit and vegetables before eating them can help avoid allergic reactions. Cooked fruit and vegetables do not usually cause any cross-reactivity.
Below are some examples of allergies frequent cross-reactivity between pollen and fruit/vegetables.
If you are allergic to birch tree pollen you could also be allergic to:

  • Apple
  • Carrot
  • Celery
  • Hazelnut
  • Peach
  • Pear
  • Raw potato

If you are allergic to ragweed pollen you could also be allergic to:

  • Bananas
  • Melons
  • Watermelon
  • Tomatoes

If you are allergic to mugwort  pollen could also be allergic to:

  • Apples
  • Carrots
  • Celery
  • Kiwi
  • Peanuts
  • Spices (cumin, parsley, coriander, anise, fennel).

Prevent allergies

The only way  to avoid for sure any allergic reactions is to avoid food that contain allergens. However, despite all precautions, it is  possible to enter in contact with allergens accidentally. In everyday life, it is very important to minimize the risk of inadvertent assumption of incriminated food.

  • Do not give anything for granted! Carefully read labels to make sure a certain food does not contain traces of what you are allergic to.-
  • If in doubt, refuse! It is not always easy to identify all the ingredients, e.g. when it comes to a dinner out, so better not risk. Not everybody understand how serious an allergic reaction is.
  • If the allergic person is a child, all relatives, teachers and the baby-sitter must be involved.

Make it clear to all the people who are part of the every day life of your son how important it is that the child avoid contact with any foods that can cause him an allergic reaction and teach them what to do in case of an emergency.