Allergic diseases are a group of diseases caused by an individual’s hypersensitivity to certain foreign substances – allergens and occurring with the development of an IgE-mediated reaction of the immune system. The necessary conditions for the occurrence of allergies are high specificity (reaction strictly to certain antigens), sensitization (hypersensitivity to this allergen) and repeated exposure of the allergen to the body.

The term “allergy”, meaning “response, reaction to someone else” in Greek, was proposed by the Austrian pediatrician K. von Pirke in 1906. Over the past century, allergic diseases have acquired epidemic proportions, and the prevalence of allergies among adults and children continues to increase steadily. According to research, 35% of residents suffer from various allergic diseases in Western countries, in USA – from 17.5% to 30% of the population. These circumstances led to the allocation of a special medical discipline – allergology, which deals with the study of diseases associated with hypersensitivity reactions. The most common allergic diseases include allergic rhinitis, bronchial asthma, urticaria, atopic dermatitis.

The ethological classification of allergic diseases is based on the isolation of a causally significant allergen; within it, food, household, insect, medicinal, and infectious allergies are differentiated. According to the method of penetration into the body, aeroallergens, contact, oral, injectable allergens are distinguished. Taking into account the conditions in which an allergic reaction has developed, domestic, professional, seasonal allergies are distinguished. Depending on the predominant lesion of a particular organ system, the following groups of allergic diseases are distinguished: allergodermatoses (atopic dermatitis, eczema, urticaria, etc.), intestinal allergoses (allergic enterocolitis), respiratory (allergic rhinitis, allergic tracheobronchitis, bronchial asthma), acute allergic reactions (Quincke’s edema, anaphylactic shock).

The symptoms of various allergic diseases are caused by common pathogenetic mechanisms: the release of mast cell mediators and basophils into the tissues or into the blood, which cause characteristic vascular and smooth muscle reactions: edema, hyperemia, itching, hypotension, difficulty breathing.

In this case, the specific form of allergy depends on which organ or tissue the allergen comes into contact with immunoglobulin E, fixed on the cell surface. If this happens in the respiratory tract, a clinic of allergic rhinitis or bronchial asthma may develop, allergic conjunctivitis in the conjunctiva of the eye, urticaria in the surface layers of the dermis, Quincke’s edema in the subcutaneous tissue, etc. Since allergic diseases have extremely diverse manifestations, allergists work closely with dermatologists, pulmonologists, otolaryngologists, gastroenterologists, ophthalmologists, nutritionists and doctors other specialties.

The specific diagnosis of allergic diseases consists in collecting an allergological history, conducting allergy testing (allergy tests and provocative tests), determining general and allergen-specific IgE, if necessary, performing functional studies (spirometry with samples, peak flowmetry). After identifying the causal allergen, it is necessary to take immediate measures to eliminate it, i.e. completely exclude contact with the substance that provokes an allergic disease.

To this end, it may be necessary to change eating habits, abandon the use of certain cosmetics, get rid of upholstered furniture and carpets in the house, stop taking certain medications, change the scope of professional activity, etc. Modern principles of treatment of allergic diseases provide for specific hyposensitization (ASIT) by introducing allergens into the body in gradually increasing doses. After a full course of ASIT, persistent remission can be achieved in 70-80% of cases. Various groups of drugs are used for non-specific therapy of allergic diseases: antihistamines, cromons, corticosteroids, bronchodilators, etc. From non-drug methods, acupuncture, climatotherapy, homeopathy, phytotherapy are used.

The section “Allergic diseases” of this medical handbook provides information on the most common violations of immunological reactivity. These materials competently tell about modern views on the causes and features of the course of allergic diseases, as well as approaches to their diagnosis and treatment

cold allergy

Cold Allergy

Cold allergy is a hypersensitivity reaction in response to exposure to low temperatures with the appearance of rashes on the skin like contact dermatitis, urticaria. The main symptoms are redness of open areas of the skin, the appearance of blisters and erosions, peeling, cracks, itching. Diagnostics includes the collection of anamnesis, clinical examination of the…

arthus phenomenon

Arthus Phenomenon

Arthus phenomenon is a kind of local hypersensitivity reaction, the peculiarity of which is the formation of immune complexes in the blood and damage to the microcirculatory bed of various tissues and organs. Most often there is a form of pathology that occurs after the administration of drugs. Its symptoms are sharp redness, pain, swelling…

serum sickness

Serum Sickness

Serum sickness is a systemic allergic reaction that develops during sensitization to foreign proteins entering the body with serums, vaccines, blood components, and medications. The disease is manifested by polymorphic rash, angioedema, enlarged lymph nodes, fever, in severe cases – anaphylactic reaction. Diagnosis involves a thorough collection of anamnesis, analysis of clinical symptoms and laboratory…

heiner syndrome

Heiner Syndrome

Heiner syndrome is a rare allergic disease of childhood characterized by an abnormal reaction of the body to cow’s milk proteins. Symptoms include damage to the respiratory system (cough, shortness of breath, hemoptysis), underweight in infants and other signs of lag in physical development, dyspeptic disorders. Diagnosis is made by microscopic examination of sputum and…



Pseudoallergy is an increased reactivity to certain substances entering the body, with the development of clinical signs characteristic of a true allergy. At the same time, there are no immunological reactions that occur with allergies, and the inflammatory process develops due to a violation of histamine metabolism, inadequate activation of complement and other mechanisms. For…

food allergy

Food Allergy

Food allergy is one of the most common allergic conditions caused by intolerance to compounds in some foods. The manifestations of the disease are diverse: skin symptoms (rashes, itching, urticaria), gastrointestinal disorders (dyspeptic disorders), sometimes systemic anaphylactic reactions are possible. Diagnosis is made by setting up skin allergological tests, studying the patient’s anamnesis and food…

angioneurotic edema

Angioneurotic Edema

Angioneurotic edema is an acute disease characterized by the appearance of a clearly limited angioedema of the skin, subcutaneous tissue, as well as the mucous membrane of various organs and systems of the body. The main causal factors are true and false allergies, infectious and autoimmune diseases. Angioedema occurs acutely and passes within 2-3 days.…

acute allergic reactions

Acute Allergic Reactions

Acute allergic reactions are pathological conditions that arise due to hypersensitivity of the body to allergens penetrating from the outside and are characterized by the sudden development of localized or generalized allergic reactions. Localized forms include urticaria, angioedema, laryngospasm and bronchospasm, systemic – anaphylactic shock and common toxic-allergic dermatitis. Manifestations of an acute allergic reaction…

non–allergic rhinitis with eosinophilic syndrome

Non-Allergic Rhinitis with Eosinophilia Syndrome

Non-allergic rhinitis with eosinophilia syndrome (NARES) is an inflammatory disease of the nasal mucosa, non-IgE-mediated, associated with the influence of non-specific non-allergic and non-infectious triggers: meteorological, chemical, medicinal. The main clinical manifestations of non–allergic rhinitis with eosinophilic syndrome are difficulty in nasal breathing, runny nose, unexpressed sneezing. Concomitant allergic diseases are not detected, allergological tests…

drug induced dermatitis

Drug induced Dermatitis

Drug-induced dermatitis is an inflammatory skin change that occurs with the external, internal or parenteral use of a particular medication. Such dermatitis is most often caused by an allergic reaction to a drug. It is manifested by the appearance of areas of hyperemia, swelling, peeling; itching, burning and wetness of the affected areas of the…