Allergy: what is it, how does it arise and its symptoms? Types of allergies and allergens

An allergy is an exaggerated defensive reaction of the body to a certain external factor - called an allergen. The reaction can be both general and local. It depends mainly on the way the allergen enters the body of the individual.

Etiology, symptoms, types of allergies and allergens, diagnosis, treatment options and other interesting information can be found in the article.

What is an allergy?

Allergy is the name for a disease of the human immune system, in which there is an immunopathological reaction to a certain, for the allergic organism, negative stimulus from the external environment.

The substances (stimuli) in question are natural for a healthy individual and are generally not harmful to health. However, this does not apply to people suffering from allergies, as their immune system evaluates the substances in question as foreign or dangerous.

Allergies come in many forms, manifestations and symptoms, from milder local symptoms (sneezing, itchy eyes, stuffy nose), to whole-body or combined reactions, to anaphylactic shock.

An allergic hypersensitivity reaction occurs when a "harmful" stimulus enters the body. The stimuli that trigger the allergic reaction are called allergens.

When an allergic reaction occurs and an allergen enters the body, the body reacts by releasing increased amounts of histamine, which is then responsible for allergic adverse symptoms and manifestations.

The number of allergic people in the world is constantly increasing. At least 25% of the population of developed countries is allergic to a particular allergen.

The increase in allergies is still being studied by the scientific community, but is mainly attributed to lifestyle changes, nicotine smoking, inhalation of exhaust fumes, minimal physical activity, excessive exposure to stress, exhaustion and other other lifestyle factors.

The origin of allergies is not fully understood by the scientific community. However, allergies are caused by a pathology of the immune system, which reacts sensitively to various factors and substances.

Behind the immune system disorders are mainly genetic predisposition and external factors during the life of an individual. Examples of external factors are lifestyle or long-term exposure to certain substances at work.

A person can have an allergy to one particular allergen and to several independent allergens at the same time.

However, there is a concept of cross-allergy, which often arises from the similarity of individual allergens.

There are several forms of immune disorders and allergy is just one of them:

Immunodeficiency - an insufficient and weak immune system of the organism. It is manifested by frequent infections and insufficient response to treatment.

Autoimmune diseases - the body's own body fights against itself and evaluates its own cells as dangerous.

Immunoproliferation - the disease arises from excessive cell growth or exuberance. This includes mainly haematological or cancer diseases.

Allergy - hypersensitivity of the immune system. The body of an allergic person resists certain substances that are harmless to a healthy individual.

Classification of allergies and allergens

Allergens (substances that are evaluated as harmful by allergists) are divided mainly according to the way they enter the body.

Types of allergens:

• Inhalant allergens
• Food allergens
• Medicines and pharmaceuticals
• Insect bites
• Other and contact allergens

Inhalant allergens are behind the most well-known allergies. These are substances that a person inhales through the respiratory tract. They include pollen, dust, dust mites, grasses, herbs, molds, animal allergens and many other substances.

The most potent animal allergens are found in the saliva, glandular secretions and urine of animals. Microscopic particles also float in the air and settle on surfaces in the home. These are mainly cat, dog and rodent allergens.

Food allergens form a broad group of substances that cause adverse reactions in the body when consumed. Important food allergens include eggs, milk, wheat flour, nuts, soy, fish and various fruits.

Allergy sufferers may have different sensitivities to food allergens. Some react to as little as microgram quantities of allergens in food with the threat of an anaphylactic reaction, while others tolerate the quantities and react to larger amounts of allergen in food.

Drugs and medicines can cause adverse reactions in some allergic people. Allergens can be penicillin, neomycin and other types of antibiotics, barbiturates or local anaesthetics.

Insect bites - an allergic reaction can also be caused by being bitten or stung by a particular species of insect. The main insects represented in our area are the wasp, bee, hornet or bumblebee.

Other allergies include substances or stimuli that cause adverse reactions when in contact with the allergic person. These include allergies to sunlight, cold, latex and others.

The primary point for the diagnosis and symptoms of allergy is the causal link between the "harmful" stimulus and the allergic person's symptoms. It is contact with the allergen that triggers allergy symptoms, but if contact is eliminated, the unwanted allergy symptoms subside.

The exact symptoms and manifestations of the allergy depend on the medical condition, the method of penetration and the amount of allergen in the allergic person's system.

Often it is a common inhalation of an inhaled allergen, which may manifest itself as a full nose, sniffling or sneezing. Respiratory allergies may manifest themselves as coughing, chest tightness or wheezing when breathing.

Inhalant allergen may irritate the eyes by itching, redness or local swelling of the eyelid.

Skin irritation is often associated with redness, eczema, swelling, specific rashes or other undesirable skin manifestations.

Food allergens can cause local swelling of the oral cavity, nausea, vomiting, watery stools and other digestive problems.

If the allergen enters an individual's bloodstream, for example from an insect bite or sting, the subsequent symptoms can be dangerous. Increased shortness of breath, labored breathing or a drop in blood pressure may be present.

Decreased blood pressure, pallor and the presence of a cold sweat is also referred to as anaphylactic shock.

The clinical picture of an anaphylactic allergic reaction depends on the amount of the injected substance and the release of histamine from the site of involvement.

Vasodilation of the blood vessels, haemoconcentration, hypovolaemia, tachycardia (increase in heart rate), bronchoconstriction (narrowing of the bronchial tubes) and subsequently an increase in respiration and lung function occur within a short time.

Types of allergies by manifestation:

• Respiratory allergies (sniffles, stuffy nose...)
• Ocular allergic manifestations (redness, itching...)
• Skin allergies (rash, swelling, itching...)
• Gastrointestinal allergies (nausea, abdominal pain...)
• General allergies (weakness, fatigue, dizziness...)
• Anaphylaxis and anaphylactic shock

Respiratory and cardiovascular symptoms:

• Stuffy nose
• Sniffling and sneezing
• Itchy nose
• Coughing
• Difficulty breathing
• Whistling when breathing
• Pressure in the chest
• Changes in blood pressure

Ocular manifestations of allergy:

• Swelling of the eyelids
• Redness of the eyes
• Itchy and burning eyes
• Increased watery eyes
• Light-headedness

Gastrointestinal manifestations of allergy:

• Nausea and vomiting sensation
• Abdominal pain
• Diarrhea or constipation
• Vomiting
• Swelling of the mouth or tongue
• Indigestion

Skin manifestations of allergy:

• Swelling/edema
• Redness
• Rash
• Hives - urticaria
• Eczema
• Itchy skin

General manifestations of allergy:

• Fatigue and weakness
• Headache
• Nausea
• Dizziness
• Sweating
• Anaphylaxis

Allergies and specific allergens must be diagnosed by a specialist allergist (immunologist).

The first step is a basic examination by sight, touch, hearing and palpation. This includes taking a complete medical history, with an emphasis on family history, as well as talking to the patient about their clinical symptoms.

The physician determines the cause of the worsening of the reported symptoms.

The basis of the diagnostic procedure is the allergen skin test. It is performed on the forearm of a patient with a suspected allergy. Diluted drops of various allergens are applied to the skin.

The skin is gently irritated in the area of the allergen drop. The individual skin reaction is then evaluated for each allergen separately.

As part of the diagnosis, a blood sample may be taken from the patient to determine the level of specific allergen IgE antibodies. Individual allergens or a group of specific allergens may be examined.

If an immune system disorder other than allergy is suspected, laboratory tests are performed for immunodeficiency (defensive antibodies/cellular immunity), autoimmunity (autoantibodies), inflammatory parameters in the blood and antibodies in the context of an infection in the body or its duration.

Allergy testing usually includes functional tests (spirometry, lung function tests) or microbiological tests (culture of upper respiratory tract mucus, urine sample) and in some cases referral for imaging (CT, X-ray, MRI).

Spirometry is an uncomplicated examination to determine the condition, capacity and performance of the patient's lungs. It is a functional examination, especially in patients allergic to inhaled allergens.

The result of spirometry is a graph showing the volume of air inhaled and exhaled over time.

Prevention of allergy

Since allergy is mainly determined by a genetic factor, there is no prevention as such. However, with a suitable lifestyle, elimination of allergenic stimuli and adherence to regular treatment, allergy symptoms can be significantly eliminated.

The influence of the mother's lifestyle and environment is still being investigated as part of the primary prevention of allergy during pregnancy.

Elimination diets in the sense of eliminating potentially allergenic foods from the mother's diet have not shown direct evidence of a positive effect on the newborn. However, it is necessary for the mother to respect and supervise her own allergies during pregnancy and breastfeeding.

Breastfeeding has a beneficial effect on reducing the incidence of allergy in babies fully breastfed until the 4th-6th month.

In contrast, maternal smoking during pregnancy increases the risk of allergies and asthma in the child.

Secondary prevention at diagnosis of allergy involves maximal elimination of allergen stimuli and lifestyle modification.

In the context of food allergies, prevention is unequivocal, namely avoidance of allergen consumption and education about the composition of foods and food allergies.

Allergy sufferers to animal allergens are strongly discouraged from being near the animal in question in the home.

Allergic to dust, dust mites, moulds and other similar allergens are advised to modify their home and work environment.

Allergy prevention advice and tips:

• Wash and change bedding at least once every 2 weeks.
• Wash bedding at 60 degrees
• Use of non-irritating hypoallergenic laundry detergents
• Eliminating carpets, curtains and similar textiles
• Vacuuming and dusting at least once a week
• Cleaning and wiping wet dust
• Use of an air purifier in the home
• Application of protective window netting against insects and pollen
• Elimination of houseplant irritants
• Use of hypoallergenic cosmetic products

You can also find useful information about allergies in the article anaphylactic shock. You will also find information about what first aid is for a severe allergic reaction.