Allergic reactions

Allergic reactions are hypersensitivity of the body's immune system when it comes into contact with an irritant. According to statistics, allergic reactions occur in approximately twenty percent of the world's population, with about half of the cases occurring in areas with poor ecology.

The incidence of allergic reactions increases approximately two to three times every ten years. The deterioration of the environmental situation and stress play a significant role in this. The most common factors that can provoke an allergic reaction include cosmetics and medications, household chemicals, poor nutrition, insect bites, dust, pollen, and animal hair. Clinical manifestations of allergies can be localized on any part of the body, including the nose, lips, eyes, ears, etc. To identify the allergen, skin scarification tests are performed with the intradermal introduction of a small amount of the suspected allergen. During drug treatment of allergic reactions, contact with the allergen is completely excluded.

[ 1 ]

Causes of allergic reactions

The cause of an allergic reaction is an acute response of the immune system to irritants, leading to the release of histamines. Allergies can occur when an allergen comes into direct contact with the skin, when inhaled, consumed with food, etc. The most common allergens include animal hair, bee stings, fluff, dust, penicillin, food, cosmetics, medications, pollen, nicotine smoke, etc. The causes of allergic reactions also include digestive disorders, inflammatory processes in the intestines, and the presence of worms. Any pathologies of the gastrointestinal tract, liver, and kidneys significantly increase the risk of allergic reactions. In small children, the cause of allergies can be the refusal to breastfeed and the transition to artificial feeding. The causes of allergic reactions can be the following:

• Unfavorable environmental conditions.
• Frequent acute respiratory viral infections.
• Hereditary predisposition.
• Chronic obstructive pulmonary diseases.
• Skin hypersensitivity.
• Nasal polyps.

[ 2 ]

Mechanism of allergic reaction

The detailed mechanism of development of an allergic reaction is as follows:

Primary contact with an allergen.

Formation of immunoglobulin E. At this stage, specific antibodies accumulate and are produced, which bind only to the irritant that causes their formation.

Attachment of immunoglobulin E to the membrane of mast cells containing mediators of allergic reactions - histamines, serotonin, etc.

The body acquires a specific increased sensitivity to an allergen. During the period of increased sensitivity (sensitization), immunoglobulins E bound to the membrane of mast cells accumulate in the body. Clinical manifestations of allergy are absent during this period, and antibodies accumulate. The reaction of antibodies and antigens causing allergy does not yet occur at this stage.

Secondary contact with the allergen and the formation of immune complexes on the mast cell membrane. The allergen binds to antibodies and an allergic reaction occurs.

Release of allergy mediators from mast cells, tissue damage.

The effect of mediators on organs and tissues. At this stage, blood vessels expand, their permeability increases, smooth muscle spasm occurs, nerve stimulation and mucous secretion occur.

Clinical manifestations of allergies include skin rashes, itching, swelling, shortness of breath, lacrimation, etc.

Unlike immediate reactions, delayed-type allergies are caused not by antibodies, but by increased sensitivity of T cells. In such cases, only those cells on which the immune complex of antigens and sensitized T lymphocytes have been fixed are destroyed.

Pathogenesis of allergic reactions

All types of allergic reactions are a consequence of a disturbed response of the body's immune system. The pathogenesis of allergic reactions consists of an acute and a delayed period. When the body is hypersensitive to a substance, there is excessive secretion of immunoglobulin E instead of immunoglobulin M upon the first contact with the antigen or immunoglobulin G upon repeated contact. The body's sensitivity increases during the process of binding of immunoglobulin E secreted upon the first contact with crystallizing fragments of immunoglobulin on the surface of mast cells and basophilic granulocytes. Upon the next contact, histamine and other mediators of inflammatory reactions are released and external signs of allergy appear. The period of delayed hypersensitivity occurs after the activity of mediators of the inflammatory reaction has weakened and is caused by the penetration of different types of leukocytes into its epicenter, which replace the affected tissues with connective tissue. As a rule, the period of a delayed allergic reaction occurs four to six hours after the acute reaction and can last for one to two days.

Stages of allergic reactions

Immune stage. Begins from the moment the immune system first comes into contact with the allergen and continues until the onset of increased sensitivity.

Pathochemical stage. Occurs during secondary contact of the immune system with the allergen; at this stage, a large number of bioactive substances are released.

Pathophysiological stage. At this stage, the functions of cells and tissues are disrupted and they are damaged by bioactive substances.

Clinical stage. Is a manifestation of the pathophysiological stage and its completion.

Manifestation of allergic reactions

Allergic reactions may manifest in the cardiovascular, digestive and respiratory systems, as well as in the skin. The main manifestations of allergic reactions, depending on the type of allergy, are skin rashes, redness and painful tickling irritation of the skin, eczema, erythema, eczematides, swelling and redness of the oral mucosa, digestive system disorders such as abdominal pain, diarrhea, vomiting, nausea. The patient may have watery eyes, a wheezing cough, a runny nose, wheezing in the chest, headaches, and redness of the eyelids. Allergic manifestations can be concentrated in virtually any part of the body, including the face, lips and eyes. Allergic manifestations are divided into respiratory, food and skin. Respiratory manifestations of allergic reactions affect various parts of the respiratory tract. These include allergic year-round and seasonal rhinitis (hay fever), allergic tracheobronchitis, and bronchial asthma. The main symptoms of allergic rhinitis are itching and nasal congestion, frequent sneezing, watery nasal discharge, lacrimation, and general deterioration in health. With allergic tracheobronchitis, a dry cough occurs, most often at night. One of the most severe forms of respiratory allergic reactions is bronchial asthma, accompanied by asthma attacks. The manifestations of food allergies can be quite varied. Often these are lesions of the skin, respiratory organs, and gastrointestinal tract; eczema and neurodermatitis may occur. Most often, food allergic manifestations are localized on the bends of the elbows and knees, on the neck, face, and wrists. Skin allergic reactions manifest themselves in the form of urticaria, Quincke's edema, and atopic dermatitis. Urticaria is characterized by a rash and swelling of a certain area of the body, which, as a rule, does not cause itching and goes away within a short time. Quincke's edema is an extremely dangerous form of allergy. In addition to a skin rash, there is pain, swelling, and itching; swelling of the larynx causes an attack of suffocation. Atopic dermatitis is characterized by inflammation of the skin, which can be combined with rhinoconjunctivitis and bronchial asthma.

Local allergic reaction

A local allergic reaction may manifest itself in the skin, gastrointestinal tract, mucous membranes, and respiratory tract. A local allergic reaction on the skin is characterized by its dryness, hypersensitivity, itching, redness, rash, and blistering. Skin manifestations of allergy may change their location, moving to different areas of the skin. An example of a local allergic reaction is atopic or contact dermatitis. A local allergic reaction may manifest itself in the gastrointestinal tract, and its symptoms are usually abdominal pain, nausea, and diarrhea. When allergy symptoms are localized in the eye area, the patient complains of lacrimation, swelling and redness of the eyelids, burning, and painful, tickling irritation in the eye. Such symptoms occur, for example, with allergic conjunctivitis. From the respiratory system, signs of a local allergic reaction are rhinitis or nasal congestion, dry cough, sneezing, wheezing in the chest, difficulty breathing (for example, with allergic rhinitis or bronchial asthma).

Allergic reaction on the skin

An allergic reaction on the skin, or allergic dermatitis, is characterized by an acute inflammatory process on the surface of the skin and is divided into the following types:

Contact allergic dermatitis occurs only in people who have immune cells specific to a substance — T-lymphocytes. The cause of such an allergy can be, for example, a completely harmless substance that does not cause any symptoms in a healthy person. However, it should be noted that contact allergic dermatitis can also occur when in contact with aggressive agents that are part of various medications, dyes, detergents, etc.

Toxic-allergic dermatitis is characterized by acute inflammation of the skin surface, sometimes of the mucous membranes, developing under the influence of toxic-allergic factors that enter the body through the respiratory or digestive system, as well as through injections into a vein, under the skin and into a muscle. Consequently, the effect on the skin is not direct, but hematogenous.

Atopic dermatitis (diffuse neurodermatitis). The main symptoms are itching and rashes on the skin, including the face, armpits, elbows and knees. This form of allergy can be the result of genetic predisposition and have a recurrent course. There are suggestions that factors such as infectious pathologies, poor hygiene, climate change, food allergens, dust, and chronic stress also play a role in the development of atopic dermatitis.

Fixed erythema is characterized by the formation of one or more round spots about two to three centimeters in size, which after a few days first acquire a bluish tint and then brown. A blister may form in the middle of such a spot. In addition to the skin surface, fixed pigmented erythema can affect the genitals and the oral mucosa.

[ 3 ], [ 4 ], [ 5 ]

Allergic reactions in dentistry

Allergic reactions in dentistry may occur when a patient is given a medication. Clinical symptoms of such reactions may include swelling and inflammation at the injection site, hyperemia and painful tickling irritation of the skin, conjunctivitis, nasal discharge, urticaria, swelling of the lips, difficulty swallowing, coughing, and in the most severe cases, anaphylactic shock, loss of consciousness, or asthma attack. To provide first aid to a patient, any dental office should have such medications as prednisolone, hydrocortisone, adrenaline, euphyllin, and antihistamines.

[ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ]

Allergic reaction to anesthesia

An allergic reaction to anesthesia, or more precisely, to an anesthetic solution, is relatively common, due to the presence in its composition, in addition to the anesthetics themselves, of preservatives, antioxidants and other substances. Clinical manifestations of an allergic reaction to anesthesia are divided into mild, moderate and severe. Mild allergies are characterized by itching and reddening of the skin, and subfebrile temperature may be observed for several days.

Moderate allergy develops within a few hours and can be life-threatening for the patient. Severe reactions include Quincke's edema, accompanied by an attack of asphyxia, and anaphylactic shock. Anaphylactic shock can develop within minutes after anesthesia, sometimes it appears instantly and can occur even with the introduction of small doses of anesthetic. After the introduction of anesthetic, tingling, itching on the skin of the face, arms and legs, a feeling of anxiety, loss of strength, heaviness in the chest, pain behind the breastbone and in the heart area, as well as in the abdomen and head are felt. If a mild allergy to anesthesia occurs, an antihistamine is administered intramuscularly, for example, a 2% solution of suprastin. In case of moderate allergy, the introduction of antihistamines is combined with symptomatic treatment. In case of a sharp deterioration in the condition, glucocorticoids are administered intramuscularly or intravenously. First aid for anaphylactic shock consists of administering a solution of adrenaline hydrochloride (0.1%) to the site of anesthesia.

[ 11 ], [ 12 ], [ 13 ], [ 14 ]

Allergic reactions during pregnancy

Allergic reactions during pregnancy increase the risk of a similar reaction in the fetus. If a pregnant woman develops an allergy, taking various medications can affect the blood supply to the fetus, so their choice should be agreed with the attending physician to minimize the risk of negative effects. To prevent food allergies, it is advisable to prescribe a hypoallergenic diet with the exclusion of foods that most often cause allergic reactions. Taking vitamin and mineral complexes is also recommended. Pregnant women should avoid inhaling tobacco smoke, regularly ventilate the room and prevent dust accumulation, and contact with animals should also be limited. Allergic reactions during pregnancy can occur against the background of hormonal changes in the body and, as a rule, pass at twelve to fourteen weeks. A mandatory condition for any allergic reactions is the exclusion of contact with the allergen.

[ 15 ], [ 16 ], [ 17 ], [ 18 ]

Allergic reactions in children

One of the most common allergic reactions in children is atopic dermatitis. It should be noted that incorrect treatment tactics for the disease can lead to the development of a chronic form. The main symptoms of allergic dermatitis include rashes on various parts of the body, accompanied by itching. The main cause of such conditions is genetic predisposition. Among the allergic factors that can provoke atopic dermatitis in infants and young children, hypersensitivity to cow's milk protein and egg white is noted. In older children, atopic dermatitis can be caused by dust, animal hair, fungus, plant pollen, worms, synthetic clothing, temperature and humidity changes, hard water, stress and physical activity, etc. In addition to itching and rash, redness of the skin is noted, it becomes dry, thickens and peels. A complication of atopic dermatitis can be fungal infection of the skin and mucous surfaces.

[ 19 ], [ 20 ], [ 21 ], [ 22 ]

Allergic reaction to vaccination

An allergic reaction to a vaccination may manifest itself in the form of urticaria, Quincke's edema, Lyell's syndrome, serum sickness, anaphylactic shock. In case of hypersensitivity to antibiotics or egg white, there is a high probability of developing an allergy to the measles, rubella, mumps vaccine, and in case of yeast intolerance - to the hepatitis B injection. An allergic reaction to a vaccination in the form of urticaria is accompanied by itching and skin rashes, and usually develops from several minutes to several hours after the injection. In case of Lyell's syndrome, a rash, blisters appear on the body, and the skin begins to itch.

Such a reaction may develop within three days after the vaccine is administered. In case of an allergic reaction to the vaccine, serum sickness may develop one to two weeks after its administration, combining the symptoms of urticaria and Quincke's edema, accompanied by fever, enlarged lymph nodes, spleen, and joint pain.

Serum sickness can have a negative effect on the functioning of the kidneys, lungs, gastrointestinal tract, and nervous system. Anaphylactic shock in an allergic reaction to a vaccination can occur rapidly or within three hours, and is, along with Quincke's edema, an extremely life-threatening condition, accompanied by a sharp drop in blood pressure and an attack of asphyxia. In cases of such reactions, anti-shock therapy is administered.

[ 23 ], [ 24 ], [ 25 ], [ 26 ]

Allergic reaction to Mantoux

An allergic reaction to Mantoux may occur with an allergy to tuberculin. In addition, a reaction to a tuberculin injection is one of the forms of allergic reactions, since it is, for the most part, an allergen, not an antigen. But the process of interaction between tuberculin and the immune system remains not fully understood. The results of the Mantoux test may be affected by food or drug allergies, allergic dermatitis, as well as any other types of allergic reactions. Also, factors affecting the test results include past infections of various kinds, chronic diseases, immunity to non-tuberculous mycobacteria, and the patient's age. An allergic reaction to Mantoux may be the result of excessive sensitivity of the skin, an unbalanced diet in children, and may occur during menstruation in females. Helminthic invasion, adverse effects of environmental factors, and violations of tuberculin storage conditions can also affect the test results.

[ 27 ], [ 28 ], [ 29 ], [ 30 ], [ 31 ], [ 32 ], [ 33 ]

Types of allergic reactions

1. Anaphylactic reactions (mild, moderate and severe).

The affected area is the skin, mucous membranes, upper respiratory tract, bronchi, gastrointestinal tract, cardiovascular system, and central nervous system. Mild anaphylactic reactions are characterized by tingling in the extremities, itching, swelling of the eyelids, nasal mucosa, oral cavity, etc. Symptoms usually appear within two hours after contact with the allergen and persist for one to two days. Moderate anaphylactic reactions usually begin in the same way as mild ones and last one to two days. Bronchospasm, shortness of breath, cough, urticaria, eczema, etc. may occur. Severe anaphylactic reactions are an extremely life-threatening condition, usually develop rapidly, and begin with symptoms typical of mild reactions. In a matter of minutes, severe bronchospasm occurs, the larynx and gastrointestinal mucosa swell, breathing becomes difficult, blood pressure drops sharply, heart failure and shock occur. The faster the anaphylactic reaction develops, the more severe it is.

2. Humoral cytotoxic reactions This type of reaction is carried out, like the first, by humoral antibodies. However, in cytotoxic reactions, the reactants are IgG and IgM. The second type of reactions include hemolytic anemia, autoimmune thyroiditis, a decrease in granulocytes in the blood caused by taking medications, a decrease in platelets, etc.
3. Immune complex type of reactions

Immune complex reactions occur, as in the second type, with the participation of IgG and IgM. However, in this case, antibodies interact with soluble antigens, and not with those on the surface of cells. Examples of such reactions are serum sickness, some forms of allergy to drugs and food products, autoimmune diseases, glomerulonephritis, allergic alveolitis, etc.

4. Delayed reactions

Examples of this type of reaction are contact dermatitis, tuberculosis, brucellosis, mycosis, etc. Cytotoxic T-lymphocyte interacts with a specific antigen, releasing cytokines from T-cells, which mediate the symptoms of delayed hypersensitivity.

Toxic-allergic reaction

An acute toxic-allergic reaction may occur when administering any medication and manifest itself as urticaria, erythema, epidermal necrosis with subsequent detachment from the dermis. The pathogenesis of a toxic-allergic reaction consists of the development of nonspecific generalized vasculitis, which causes four degrees of disease severity. At the first and second degrees of severity, the patient is treated in the allergology, therapy or dermatology department, at the third and fourth degrees - in the intensive care unit. Clinical manifestations of a toxic-allergic reaction, depending on the severity, may include an increase in body temperature, lesions of the skin, mucous membranes, liver and pancreas, urinary system, cardiovascular and central nervous system.

Immediate allergic reactions

Immediate-type allergic reactions usually appear within twenty to thirty minutes after secondary contact with the antigen and are associated with the production of antibodies. Immediate-type allergic reactions include anaphylaxis, atonic disease, serum sickness, acute necrotic hemorrhagic inflammation, and diseases of the immune complexes (IC). The immune response to allergens, which in the case of immediate-type hypersensitivity may be dust, plant pollen, food, medication, microbial, or epidermal factors, leads to the production of antibodies (Ab) of the immunoglobulin E or G class and increased sensitivity of the body. When the allergen enters the body a second time, it combines with antibodies, which leads to cell damage and the subsequent formation of a serous or other inflammatory process. Depending on the mechanisms of damage and the clinical picture, several types of immediate-type allergic reactions are distinguished: mediator (subdivided into anaphylactic and atopic), cytotoxic, and immune complex.

[ 34 ], [ 35 ], [ 36 ], [ 37 ], [ 38 ], [ 39 ], [ 40 ]

Delayed-type allergic reactions

Delayed-type allergic reactions are caused by T-lymphocytes and lymphokines, caused by infectious agents, chemicals, including medications. The immune reaction is associated with the formation of T-lymphocyte effectors, which produce lymphokines that affect cells containing antigens on their surface. Clinical forms of delayed-type hypersensitivity include tuberculin and trichophytosis infectious allergy, contact allergy, some forms of drug allergy and autoimmune diseases. Skin tests and test tubes (cell type) are used for diagnosis.

[ 41 ], [ 42 ], [ 43 ], [ 44 ]

Allergic reaction such as urticaria

An allergic reaction such as urticaria is characterized by the appearance of blisters on the skin and mucous membranes upon contact with an irritant. The causes of such reactions are quite varied, which is why it is not always easy to identify the allergen. An acute allergic reaction such as urticaria is usually associated with taking medications, food, infections and insect bites. Chronic urticaria is associated with pathologies of internal organs and dysfunction of the nervous system. Physical urticaria can occur when the skin is exposed to direct sunlight, heat, cold, vibration and compression. With an allergic reaction such as urticaria, signs such as the formation of blisters on the skin or mucous membranes are noted, characterized by swelling, compaction, various sizes and outlines, often with a pale zone in the middle. In acute allergic reactions such as urticaria, the onset of the disease is usually rapid, with severe painful tickling irritation of the skin, burning, rash in various places, and urticaria. Varieties of allergic reactions such as urticaria include giant urticaria (Quincke's edema), chronic recurrent urticaria, and solar urticaria. In acute forms of the disease caused by taking certain medications or food, laxatives, antihistamines, calcium chloride, and calcium gluconate are indicated. In severe cases, corticosteroids and adrenaline solution are administered. For external treatment, 1% menthol solution, salicylic acid solution, or calendula are used. In cases where the allergen cannot be detected, the patient is prescribed absolute fasting for three to five days under strict medical supervision.

[ 45 ]

Treatment of allergic reactions

Treatment of allergic reactions is primarily based on completely limiting the patient's contact with the irritant. During specific immunotherapy, the patient is given a vaccine containing a specific antigen, gradually increasing the dosage. The result of such treatment can be either a decrease in the severity of the disease or a complete elimination of hypersensitivity to the irritant. This method is based on stimulating the release of immunoglobulin G, which binds antigens before they combine with immunoglobulin E, thereby blocking the development of an allergic reaction. Medicinal products belonging to the group of antihistamines, as well as adrenaline, cortisone, and euphyllin also have the ability to neutralize the activity of inflammatory reaction mediators. Such drugs help relieve allergy symptoms, but cannot be used for long-term therapy. Enterosorbents are used as part of the therapy for allergic reactions to food or drugs. Antihistamines used in the treatment of allergic reactions are divided into first, second, and third generation groups. With each subsequent generation, the number and intensity of side effects and the likelihood of addiction decrease, and the duration of the effect increases.

• 1st generation antihistamines – fenistil, diphenhydramine, tavegil, diazolin, dramamine, diprazine, suprastin.
• 2nd generation antihistamines – Allergodil, Claritin, Zodak, Cetrin.
• 3rd generation antihistamines - lordestin, erius, telfast.

First aid for allergic reactions

First aid for allergic reactions consists primarily of immediately stopping contact with the allergen. If the allergy is caused by food, it is necessary to immediately wash out the stomach. If more than sixty minutes have passed since eating, you should take a laxative or give an enema. You can stop allergens from entering the blood with activated carbon or other sorbents. It should be noted that taking sorbents with other medications at the same time prevents the absorption of the latter, so sorbents are not taken with other medications. If an allergic reaction is caused by an insect bite, the first step is to remove the sting. To relieve swelling, ice should be applied to the affected area for about thirty minutes, and a tourniquet can also be applied over the bite site. For allergies associated with inhalation of dust, pollen, wool, etc., you should immediately take a shower, rinse your eyes and nasal passages in order to cleanse the skin and mucous membranes of allergen particles. To suppress allergy symptoms, it is necessary to take an antihistamine (claritin, suprastin, cetrin, loratadine, zodak, etc.).

[ 46 ], [ 47 ], [ 48 ]

How to relieve an allergic reaction?

The main task in eliminating allergy symptoms is to completely eliminate contact with the irritant. If the patient has difficulty breathing, self-medication should never be attempted, an ambulance should be called immediately. If an allergic reaction occurs after an insect bite, such as a bee, you should try to pull out the sting, then the affected area should be treated with soap and ice or other cold should be applied, such as a compress.

To reduce swelling, you can apply a thick mixture of soda and water to the damaged area of skin. If the allergy is caused by food, first wash the stomach and give a cleansing enema to eliminate the allergen. If you are allergic to cosmetics, immediately wash the skin with water. Hydrocortisone ointments help reduce itching and irritation of the skin. To relieve an allergic reaction, you need to take an antihistamine, if there are no contraindications to its use (cetrin, claritin, zodak, suprastin, etc.).

Nutrition for allergic reactions

Nutrition for allergic reactions must be balanced and complete. In case of allergies, it is not recommended to abuse sugar and sugar-containing products; you can use its substitutes. If you are prone to allergies, you should control the consumption of proteins, fats and carbohydrates, it is recommended to reduce salt intake. Spicy and hot dishes, seasonings, smoked foods, fatty meat and fish should also be limited or completely excluded. It is recommended to include cottage cheese and fermented milk products in the diet. It is recommended to steam, boil or bake food, but not fry it. This to some extent helps to slow down the absorption of allergens by the intestines. In addition to the main diet, vitamin and mineral complexes are prescribed, as well as calcium preparations. At the same time, products containing oxalic acid, which slows down the absorption of calcium, are excluded. Some types of fish, such as tuna or herring, contain histamine, which helps to increase allergic reactions. In case of food allergies, an elimination diet is prescribed, completely excluding the consumption of the allergen product; for example, in case of an allergy to egg whites, it is forbidden to eat eggs and any products containing them in one form or another.

Prevention of allergic reactions

Prevention of allergic reactions primarily consists of eliminating contact with the allergen, if one has been identified. For preventive purposes, it is also possible to prescribe a specially designed dietary table containing products that are balanced in energy value and hypoallergenic. To prevent allergens from entering the body, as well as to prevent repeated allergic reactions, it is necessary to correct nervous conditions, avoid stressful situations, spend more time outdoors, give up bad habits, and lead a healthy lifestyle. To prevent the development of allergic reactions, it is also recommended to perform special breathing exercises, strengthen the body with the help of hardening or physical education.