Allergies in children, symptoms and allergy tests

By Cristiano Antonino On Dec 22, 2022

Allergies in children: allergic diseases can occur at any age, from very early childhood. In Italy, in fact, they are among the most common chronic diseases among children and adolescents, with an explosion of cases in the last decade, so much so that the SIAIP, Italian Society of Pediatric Allergology and Immunology, speaks of 40% of children under 14 years of age suffering from some kind of allergy

What is meant by allergies and allergens

Allergy is a reaction of the immune system to a substance: the allergen is generally harmless to most people; however, in this case the body goes on to identify it as a foreign agent against which to implement a defense.

Allergens can be:

respiratory: certain substances with which one comes into contact by breathing (inhalants), such as, for example, pollen, animal dander, dust mites, mycophytes (molds), etc;
food: ingested foods. In infants and children, the most common are milk protein allergies, while in adults we often talk about, for example, fruits and vegetables;
drugs: the most common allergies are to antibiotics and anti-inflammatories that often result in a skin reaction such as hives;
insect venom: the venom of hymenoptera (bees, wasps, hornets);
contact: substances that cause an inflammatory reaction on contact with the skin such as metals, perfumes, rubber etc.

Our children: what are the most common allergies in childhood

Under one year of age, the most common childhood allergies are:

food (milk proteins and derivatives, eggs, honey, peanuts, tomatoes etc);
contact dermatitis (perfumes, dyes etc.).

In childhood in general, however, the most common allergies are to:

mites;
pollens and grasses;
molds and alternaria (a fungus that generates a certain mold);
animal (dog and cat) hair.

Remaining common, however, are also food allergies, for example, to milk and dairy products, peanuts, eggs etc.

Symptoms of allergies in children

Depending on the body districts affected, the symptoms that may appear depending on the type of allergy are:

lungs: asthma, cough and bronchospasm;
nose: rhinitis, itching, rhinorrhea (runny nose), nasal obstruction;
eyes: conjunctivitis, itching, tearing;
skin: eczema, urticaria, angioedema (deep tissue edema), swelling, atopic dermatitis;
gastrointestinal tract: vomiting, diarrhea, abdominal pain.

Among the most frequent symptoms in children and adolescents is definitely rhinitis, along with asthma and atopic dermatitis.

Symptoms of anaphylactic shock

During anaphylactic shock, or anaphylaxis, the immune system releases certain substances that can result in severe symptomatology that, if not treated immediately, can lead to death.

Sudden symptoms to pay special attention to in this case may be:

Angioedema and swelling;
itching of tongue and palate;
difficulty breathing and/or wheezing;
tachycardia, arrhythmia;
tingling in peripheral limbs;
nausea, vomiting;
diarrhea;
urticaria.

A considerable percentage of cases of anaphylactic shock in children and adolescents are caused by peanuts.

Allergies in children, diagnosis and allergy testing

A very important component of the allergy diagnosis process, as the doctor reminds us, is that of the medical history, so whether there are/have been other cases of allergies in the family or whether the allergic episodes can be traced back to certain situations such as, for example, taking certain foods/drugs, contact with one’s pet, etc.

This step is critical to:

figure out which allergens to include in any diagnostic tests to be performed;
identify any medications responsible for the allergic reaction. This is because that of medications is a vast category, so unfortunately, tests are available for only some of them.

When faced with a suspected allergy, the most common allergy tests that can be performed are:

prick test;
patch test;
IgE assay.

Prick tests

Prick tests or skin prick tests (SPT), from the English ‘prick’, ‘to prick’, are the most common tests for detecting food and respiratory allergies, which are performed by placing a drop of different allergenic substances on the skin of the forearms and then, as the word implies, pricking the skin underneath with a sterile lancet.

When faced with suspicion toward some specific allergens, testing is done with those, otherwise a generic selection of allergens can be used.

How they are performed

After placing a drop of allergenic extract for each allergen and, finally, a drop of histamine on the skin, small cuts are made at the affixed substances.

After a period of 15 to 30 minutes has elapsed, the physician assesses the presence of any erythematous reactions and swelling. If a pimple greater than 3 mm in diameter is formed, surrounded by a red halo, the diagnosis of allergy is positive.

Prick tests can be performed from the age of one year, in fact below that they are not reliable, taking into consideration, in any case, that under 3 years of age the reliability is not very high anyway.

The child’s skin should not be injured or have irritation, as this would affect their actual validity.

Any cortisone and antihistamine therapies should be discontinued at least a couple of weeks before performing the procedure.

Prick by prick

If the result of prick tests is negative, but symptomatology persists, prick by prick may also be used in the case of food, in which instead of the drop of extract, the lancet is dipped directly into the fresh allergen.

Patch tests

Patch tests, from the English word ‘patch,’ are another method for diagnosing, in this case, skin allergies due to contact with a particular substance (contact dermatitis).

As the word itself indicates, they involve the application to the skin of patches containing the allergenic substances.

On the upper back, which is the most sensitive area of the body, patches containing the allergens are placed, and 48 to 96 hours later they are removed (in this case, the timeline is longer than for prick tests because the skin reaction takes longer to occur).

If the area where 1 or more patches were placed is reddened or erythema occurs, the diagnosis is positive.

Cortisone and antihistamine therapies must be discontinued for at least a couple of weeks before the examination can be performed.

While the patches are attached, to prevent them from coming off, do not get them wet or engage in activities that promote sweating.

IgE assay

Another diagnostic method of allergies is the IgE antibody assay by blood sampling.

In some types of allergies (IgE-mediated allergies), in fact, the immune system that comes into contact with the allergen produces immunoglobulin E (IgE) antibodies.

Since it is possible to be allergic to multiple substances, the immune system will produce specific IgE for each of the allergens.

In relation to the measurement of IgE, there are 2 types of tests that can be performed:

specific IgE assay: depending on the type of test used, they are selected to evaluate the possible antibody response induced by the specific allergenic substances or, if no allergy suspicion could be formulated, a package of standard substances can be tested;
total IgE assay: in case the possible allergen(s) to be tested have not been identified, it may also be useful to assess only the presence of total IgE, which, if detected even at low levels, still go to signal the presence of an allergy to be identified later more precisely. This, therefore, also allows for a differential diagnosis with intolerance.

The IgE assay is the most reliable test among the 3 types indicated.

There is no need to suspend any antihistamine/steroid therapy in order to perform the test.

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Causes of allergies

The causes of allergies are still not entirely clear, but given also the presence in many allergy sufferers of a positive family history, it is hypothesized that underlying them are genetic components combined with environmental factors (smoke exposure, poor dietary habits etc.).

In particular, the incidence of environmental factors has been more emphasized in the last decade, due in part to the increasing prevalence of these diseases.

Difference between allergy and intolerance

The fundamental difference between allergies and intolerances lies in the fact that although intolerance also represents an abnormal reaction of the body toward a certain substance, in this case an immune reaction does not occur.

The symptoms may be similar to those of allergies, but there are different diagnostic procedures and therapies.

Among the most common intolerances are:

lactose intolerance, which can be diagnosed with a specific breath test;
celiac disease, which although classified as an intolerance, is in fact an autoimmune disease in which the immune system goes on to damage the intestinal villi. In this case, diagnosis can come through blood tests, intestinal biopsy, and genetic testing.

Does one recover from allergies?

The evolution of allergies is variable: in some cases, they change over the years from one form to another (e.g., transition from dermatitis to rhinitis); in others, they worsen or others regress or subside spontaneously.

There is no possibility, therefore, of establishing a general prognosis for everyone.

Treatment of allergies in children

Treatment for allergies in children varies depending on a number of factors and how severe the condition encountered is.

The main treatment strategies may include:

limiting exposure to the allergen by avoiding, depending on the type of allergy, the intake of foods, substances and medications that may contain it, or reclaiming the environment from substances such as dog/cat hair, mites etc;

antihistamines: the first therapeutic approach after the elimination of contact with the allergen is drugs that go to inhibit histamine, which is largely responsible for the inflammatory symptoms. Free, by now, of the side effects of drowsiness, these are available in various formats: eye drops, nasal sprays, creams, tablets etc;

cortisone and steroid drugs: they act by blocking the inflammatory process. Available, too, in various formats (creams, sprays, metered puffs, tablets, injectable solutions etc.) they should only be used with a doctor’s prescription and supervision as the specialist is able to establish the most suitable dosage for the child’s age, weight and characteristics;

immunotherapy: vaccines, taken orally, can also be given against some allergies. The principle is the same as for all vaccinations: a small dose of the specific allergen is given to the body, triggering a controlled immune response that will go on to protect the child from subsequent contact with it. For pollens, the vaccination cycle should be done in winter, so that they are already covered during the spring season;

adrenaline, or epinephrine: is a life-saving drug used in the presence of anaphylactic shock. It acts by inhibiting the activity of mediators that go into propagating the inflammatory state and reducing the severe symptomatology of anaphylaxis. Individuals with an established risk of anaphylactic shock are generally provided with adrenaline auto-injectors, which are otherwise administered in emergency rooms and urgent care centers.

Breastfeeding and allergy prevention in children

A number of scientific studies show that breast milk contains specific antibodies and substances that, when passed to the baby, somehow give him or her protection from various diseases including, for example, allergic diseases.

For the same reason, in breastfed babies who are allergic, for example, to certain foods, the mother may be required to follow a dietary regimen that goes to exclude them.

In addition, a second factor in preventing allergies may be the use on the baby’s skin of gentle, emollient products that are free of aggressive substances capable of triggering skin reactions.

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