Why we develop allergies and why some go away on their own

Allergy is one of the most frequent chronic immunological disorders in the world today and can begin in the first months of life or appear unexpectedly during adulthood. On the occasion of World Allergy Day, we will see why it occurs so suddenly.

They occur because immune system reacts against a substance that for most of the population is harmless.

Allergies are caused by a huge variety of substances, both biological and synthetic. The most common sources of sensitization are pollens, food, mites, animal skin, insect poisons and drugs.

When the immune system works well, our defenses attack invading microorganisms, such as viruses and bacteria, and destroy them. But in the case of allergy, the immune system misidentifies proteins that are present in the skin of a pet or in a food in perfect condition.

It recognizes them as a danger to the body and, from there, organize “their defenses”. It can happen in the same way in pollen.

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Peanuts, fish are some of the foods that can cause allergies.

Although there is a clear hereditary component, allergy may start unexpectedly with an annoying dermatitis. We can also feel a reaction to a food or a seasonal respiratory allergy.

The atopic character is part of the genetic card of an individual. Therefore, it can appear when one least expects it, so: Welcome to the allergy club!

Why do we develop allergies?

A pollen or food is allergenic because it contains protein which, complete or in fragments in most cases, are capable of activate cells and molecules of the immune system. So, they trigger the bothersome allergy symptoms.

In order to stimulate the immune system, they have to pass through the layers of epithelial cells that line our airways and our digestive system.

This cellular structure is not a simple retaining wall, though too. But it is a dynamic structure that establishes an authentic molecular, cellular and immunological conversation once an allergen passes through it.


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Antibiotics or overuse of drugs can influence the development of allergies.

This cell layer is completed with a layer of bacteria that live with us and that account for 2% of our body weight, our microbiota.

When we alter this structure, by a treatment with antibiotics or excessive consumption of drugs such as anti-inflammatories, can increase the permeability to substances such as allergens. In this way, it could trigger or even aggravate the allergy in that individual.

Allergy Treatments

Allergy treatments base their strategies on periodically administering increasing amounts of an extract containing the molecule to which they are allergic to the patient.

The goal is to achieve a gradual loss of sensitization. Ultimately, what is intended is to increase the detection threshold of your immune system.

However, although the cure for allergies such as pollen can be definitive, the hallmark of atopic is not easily lost and many of these symptoms can mysteriously reappear.

And so, suddenly, one day in May, an individual may experience a sensation of itching and watering of the eyes due to an allergy to pollen or a pet. The immune system is constantly changing.

Why do some allergies go away on their own?

However, many allergic individuals with age leave behind all the associated symptoms or even replace them with others linked to new substances.


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In many cases, the allergies that we develop as children disappear as adults.

In cases in which the symptoms that we suffer during our childhood and youth age disappear, specialists attribute it to a desensitization of the patient to allergens to which it has been exposed in a natural way. That is, it has been losing reactivity against them.

Getting used to the presence of foods in the diet, that is, desensitizing them, is one of the therapeutic strategies that are being developed successfully today for many childhood allergies, such as those of eggs, peanuts or milk.

In the last decade, the results of clinical studies carried out with this type of treatment have shown that a high percentage of children with allergies to these foods have been cured.

However, on many occasions, the serious symptoms that originate require the avoidance of the allergenic substance or a controlled desensitization treatment, the so-called specific immunotherapy, under the supervision of a specialist.

However, despite the fact that allergies seem to be disappearing for many individuals, the reality is that during the next few years living with the allergy will be something habitual for most of the world’s population.

A future with more allergies

This natural tendency for allergic symptoms to disappear, in many cases in the adult population, is being prevented precisely by certain environmental conditions and often for the excellent quality of life of our developed countries.

Girl with a cat

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Pets help pollen stay in the air longer.

There are several reasons. On the one hand, in the case of respiratory allergies, due to the increasingly frequent presence of pets in our homes or polluting particles in the environment.

These are true vehicles for keeping pollen grains suspended in the air. The appearance, as a consequence of climate change, of new botanical species in our drought-resistant fields and gardens.

All of this has led to an increase in the frequency of respiratory allergies.

On the other hand, the high threshold of hygiene, the abuse of antibiotics and chronic problems triggered by food intolerances they have caused the loss of tolerance that a good state of our mucous membranes and our immune system would suppose.

This pathology currently affects the 25% of the population. With the current rate of growth, it is expected that within two decades the percentage of the affected population could reach 40%. For this reason, there is already talk of considering it as one of the pandemics of the 21st century.

* María Teresa Villalba Diaz is Professor of Biochemistry and Molecular Biology, Complutense University of Madrid, Spainña.

* This artThe article was published on The Conversation and reproduced here under the Creative Commons license. Click here if you want to read the original version.

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