Our immune system is one of the most important in allowing us to survive, since thanks to it we are able to fight infections and problems derived from the invasion of microorganisms and substances with harmful potential from the environment.

However, such a system sometimes reacts disproportionately and wrongly to stimulations that are in principle not dangerous, to which we acquire allergy. And what causes them or the type of reaction they generate can vary greatly.

That is why we can talk about a wide variety of types of allergies , which can be classified according to various criteria. Throughout this article we will show some of the main typologies, as well as indicating some of the most frequent ones.

What is an allergy?

We call allergy to a process of biological origin through which contact or consumption of a certain substance or element triggers a massive reaction of our immune system, which identifies this element as a toxic or harmful substance to be expelled .

This is a response generated by a hypersensitivity of our organism towards the stimulus in question, which is called an allergen, and which causes our white blood cells to synthesize antibodies to fight against this element . However, it should be borne in mind that to speak of allergy properly, we must be dealing with a reaction generated by immediate contact with some type of exogenous substance, while otherwise we would be dealing with other types of hypersensitivity or disorder (although very similar).

Exposure to this allergen generates a reaction on the part of our immune system that is disproportionate and excessive in relation to the real danger that the stimulus in question may pose, either because the stimulus to which we react or allergen is in fact harmless to us or because the body’s reaction is disproportionate to the real danger that it represents (such as the venom of a bee).

Reactions to such exposure can generate a wide variety of effects on the organism that can range from mild (these being the most common) to fatal (in cases of anaphylaxis not treated in time), being a health problem of the first order that although it is usually underestimated can have severe consequences or generate difficulties in the daily lives of those who suffer them.

In turn, allergies are one of the most common problems, being the usual cause of some very common conditions in the majority of the population and it is estimated that up to 40% of the population could suffer from some type of allergy. As for what can generate it, we can find a great variability of substances and stimuli (some more frequent than others) that our immune systems can identify as dangerous, as well as the type of reaction or the route by which it can reach us. This is why we can talk about various types of allergies.

1. Types of allergies according to the route of contact

One possible way of classifying allergies is to be found in the environment through which the allergen comes into contact with the body. In this sense we find three main groups of allergies .

1.1. Inhalation allergies

This is understood as the type of allergy in which the allergenic substance is introduced into our organism through the inhalation of air, by respiratory or nasal route . These are usually small particles of substances such as pollen, dust or mites.

1.2. Contact allergies

This type of allergy is produced when direct contact at a physical level with a substance generates an allergic reaction. It is common for it to generate symptoms on a dermatological level and is frequent for example in allergy to animals.

1.3. Allergies by ingestion

Ingestion allergies are all those in which the immune system reacts virulently when it identifies a substance we have consumed as a pathogen. It is one of the types of allergy that usually has the greatest potential to generate severe damage and anaphylaxis . We usually talk about allergies to food or drugs.

1.4. Inoculation allergies

Similar to the previous one, in this case we are talking about substances that are introduced into our interior through routes such as intravenous. These are usually allergies to medications (including anesthetics) or drugs that are not consumed orally. It is probably the most dangerous of all, given that the allergen is introduced directly into the circulatory system and the reaction can be widespread throughout the body or in parts relevant to survival.

2. According to your symptomatology

Another way of classifying allergies can be found if we use as a differentiating criterion the type of symptoms generated by exposure to the allergen. In this sense, we can find mainly the following types of allergies.

2.1. Respiratory

Respiratory allergies are one of the most frequent types of allergies that exist, being understood as those that generate an affectation at the level of the breathing process . Generally, the problems are found in the lungs or in the airways, making it difficult for the subject to breathe normally and causing problems such as coughing, bronchial problems, asthma or wheezing. It is usually caused by inhalation allergies, although it is not essential.

2.2. Cutaneous/dermatological

Along with respiratory allergies, they are the most common type of allergic reaction. It is common in contact allergies, but also often occurs in allergies by ingestion or inoculation. In this case the most common type of symptom is the appearance of some type of skin rash, ulcer, sore, hives, eczema or itch . This is the case with many dermatitis.

2.3. Nasals

One of the most visible is the type of allergic reaction that causes sneezing, runny or itchy nose. Often confused with colds or flus, it usually proceeds in the same way as the respiratory symptoms of inhaling the allergen.

2.4. Eyepieces

Conjunctivitis, tearing and eye spike are allergic reactions at the eye level that often occur when allergens come into contact with our eyes .

2.5. Digestives

Other types of allergic reactions are digestive reactions, which can lead to diarrhea, vomiting, bloating, or other gastrointestinal problems. Food allergies are common, although they also appear in other types of allergy.

3. Three common varieties according to time or place of exposure

In addition to the above types of allergies, we can also find three very common varieties depending on the type of situation, time or specific place where contact with the allergen usually occurs.

3.1. Seasonal allergy

Seasonal allergies are a well-known and very common type of allergy, in which the stimulus to which you are allergic has a tendency to appear at some time or period of the year . One of the most obvious examples is pollen allergy, which tends to cause more difficulties in the spring.

3.2. Food

Food allergies are a group of allergies that have the particularity that the allergen in question is a product or substance that can generally be consumed by humans and that can be nutritionally beneficial , but that in the person in question triggers a dangerous reaction with the potential for death.

There may have been a period of time when the subject could eat the product in question normally, before he acquired an allergy. These include allergies such as those to nuts and shellfish.

3.3. Medicinal products

This type of allergy refers to the presence of an extreme and adverse reaction by the immune system to substances that are a priori designed to cure us or help us overcome some type of illness or disease. It is one of the most dangerous types and requires extreme care when choosing and administering drugs , as it can aggravate the patient’s situation or even cause death.

3.4. Occupational

We call occupational allergy the type of disorder or allergic alteration generated by some type of stimulus from our occupation or work environment. This type of allergy may appear through any contact route or manifest itself in different ways, although the most common is its appearance through the respiratory or skin route, and what is defining is that it is generated by some substance specific to the workplace .

An example could be the appearance of an allergy in workers who handle chemicals or food in factories or during research, being in continuous contact with the allergens.

Some of the most common

As we have said, there is a wide variety of stimuli that can trigger an allergy, since allergy depends on what and how our own immune system is hypersensitive to : there are ones as common as allergy to grasses to others as unusual as allergy to semen or even water. To conclude this article, we will look at four of the most common allergies.

Pollen

One of the most common allergies, generally of a seasonal nature, is the allergy to the pollen of certain plants . It usually causes nasal problems, headaches and problems in breathing normally.

To mites

A small creature highly frequent in places like our beds and sheets, it usually generates respiratory and nasal problems. It is also often associated with dust .

Food

While we are including a fairly broad category here, we felt it necessary to include it given the high prevalence of food allergies in general. We highlight allergy to nuts, allergy to seafood, allergy to dairy products (important not to be confused with intolerance, which is not the same thing) or allergy to exotic fruits.

To animal dander

Causing respiratory problems and also with the possibility of generating dermatological problems, the allergy to dandruff of animals with hair is one of the most common. Fortunately for those who, despite being allergic, want to take care of a pet, there are animals whose fur or lack of it makes it difficult for dandruff or other allergenic substances to exist.

Bibliographic references:

  • Gaitano Garcia, A. (n.d.). Allergy for nursing. Basic manual of allergology.

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  • Pawankar, R.; Canonica, G.W.; Holgate, S.T. and Lockey, R.F. (2011). WAO White Paper on Allergy. Executive Summary. World Allergy Organization.