The main link in therapy is to reduce the effect of histamine on skin tissue – this can significantly reduce swelling and itching. For this, it is necessary to block the H1-histamine receptors, this is achieved using antihistamines. Currently, preference is given to antihistamines of the second (loratadine, cetirizine) and the third (levocetirizin) generation.
These drugs are very effective in acute forms of allergic urticaria, as well as dermographic and solar pseudo-allergies. However, in chronic forms of urticaria and types with a delayed manifestation of symptoms (some types of lesions from pressure), the effectiveness of antihistamines is greatly reduced.
For the treatment of chronic forms of pathology, as well as for the prevention of exacerbations in the recurrent nature of allergic urticaria, preparations-stabilizers of basophil membranes (ketotifen fumarate) and calcium antagonists (nifedipine) are used. They significantly increase the threshold of activation of mast cells, thereby hampering the development of skin manifestations. If there is a suspicion that the development of the disease is due to a decrease in the activity of the immunity, then immunomodulatory drugs are additionally prescribed. In identifying systemic pathology, which is accompanied by an allergic urticaria, a scheme for its treatment is developed.
In addition to prescribing drugs, a hypoallergenic diet plays a significant role in the treatment of this condition in order to reduce the load on the human immune system. In addition, after determining the provoking factor (food or physical nature with pseudo-allergy), it is necessary to take measures to exclude him from the patient’s life or minimize his effects on the body. In cases where allergic urticaria is of a rapid nature and leads to angioedema or anaphylactic shock, urgent life-saving measures are necessary (injections of epinephrine and steroids, hospitalization).
Allergic urticaria (urticaria)– skin disease, manifested by the development of pruritus, erythematous rashes and usually provoked by food or other allergies. Such a condition is extremely common, according to medical statistics, at least 10-20% of the population of the Earth at least once in their lives experienced symptoms of this pathology. In the overwhelming majority of cases, allergic urticaria is acute and after treatment (sometimes spontaneously) disappears, leaving no marks on the skin or mucous membranes. The chronic form of the disease, according to some dermatologists, should be placed in a separate nosological group, as it is due to autoimmune and hereditary factors. In addition to the true allergic form, there is the concept of “pseudo-allergic urticaria”, which is caused by various physical factors.
Allergic urticaria can affect a person at any age, however, the prevalence of children is observed in the age distribution of patients. This is due to the immaturity of many immunological processes, which is why allergy to various factors easily occurs. Chronic type of allergic urticaria more often develops in female adults – in this case, it is often impossible to identify the cause of the disease, therefore it is often also called idiopathic urticaria.
By itself, this pathology does not pose a threat to human life, but it can be complicated by angioedema or anaphylactic shock. These conditions require emergency medical care to save the life of the patient.
Causes of Allergic Urticaria
The causes that cause skin manifestations are different in various forms of allergic urticaria. This is usually a reagin type of hypersensitivity (type 1 allergy) mediated by type E immunoglobulins. Allergens for this type of allergic urticaria are food components, plant pollen, household dust, some drugs and other factors.
In this case, the skin manifestations are just one of the symptoms of food or other allergies. In some cases, such skin disorders can also cause type 2 allergies – this is mainly the case with blood transfusions. Intravenous administration of certain drugs with the development of an intolerance immunocomplex reaction can also cause allergic urticaria.
It is noticed that some infectious diseases, endocrine disorders, disorders of the psycho-emotional sphere increase the likelihood of developing allergic urticaria. This is especially true for idiopathic, or chronic forms of pathology.
The pathogenesis of the development of skin disorders in this case is poorly understood; both immune and non-immune mechanisms of tissue tissue basophil activation are assumed. Therefore, in the presence of allergic urticaria of unspecified etiology, a complete examination of the patient’s body is performed in order to detect latent and chronic diseases and disorders.
Pathogenesis of allergic urticaria
The main cause of skin disorders in allergic urticaria is mass degranulation of tissue basophils (mast cells). The composition of the granules of these cells includes histamine, heparin, leukotrienes and a number of other biologically active compounds that can significantly change the metabolic processes in tissues. They mainly lead to the expansion of blood vessels, increase the permeability of their walls, cause an accumulation of tissue fluid, stimulate the pain receptors of the skin, which leads to the appearance of itching.
In most cases, such reactions in case of allergic urticaria are local in nature and affect only a certain area of the skin or, more rarely, the entire surface of the body. However, sometimes such a massive release of active compounds can lead to general reactions such as anaphylactic shock and angioedema.
In case of pseudo-allergic urticaria, the pathogenesis is largely similar – there is a massive activation of tissue basophils of the skin with the release of biologically active compounds. However, the causes and mechanisms of this process are somewhat different – it may be congenital or acquired instability of the membranes of mast cells, their abnormal reaction to various physical or humoral factors.
In addition, in some cases of pseudo-allergic urticaria, the patient is found to have an increased sensitivity of the skin tissue to histamine and other components of basophil granules. Therefore, even a small excretion of these substances can lead to a clinical picture of urticaria.
Classification of allergic urticaria
As mentioned above, all forms of allergic urticaria are divided into two types – acute and chronic. The border between them is rather arbitrary – it is believed that with an acute form of rash and itching it lasts no more than 6 weeks, whereas if they bother the patient for longer, a diagnosis of chronic allergic urticaria is made.
In addition, it is important to differentiate the true allergic urticaria from pseudoallergy, in which the activation of mast cells occurs without the participation of immune mechanisms.
There are many varieties of this state – for example, the following types of mechanical pseudoallergy include:
- Dermographic urticaria ( urticarous dermographism) – triggered by simple physical pressure on the skin (clothing stitches, for example). In the pathogenesis of dermographic urticaria, non-immune mechanisms of mast cell activation most often play the role.
- Cold urticaria – this type of temperature urticaria in recent years is becoming more common. It has been found that in patients with this pathology during cooling, the level of certain platelet factors increases and the stability of the mast cell membrane decreases. Against the background of increased sensitivity of skin tissues to histamine, this can lead to the development of erythematous rashes and itching, both with local exposure to cold and when eating cold foods and drinks.
- Thermal urticaria – is a rather rare variant of urticaria. Just as in the case of urticarial dermographism, non-immune mechanisms of mast cell activation play a major role in the development of this type of disease – their degranulation occurs when the temperature rises.
- Solar urticaria (photoallergy) – a provoking factor in this case is sunlight. In patients with this type of urticaria, there is an increased sensitivity of the skin to histamine, therefore, the degranulation of even a small number of mast cells leads to noticeable disorders.
- Vibration urticaria is a rather rare form, often showing signs of occupational disease (in construction workers, in production). In this case, the degranulation of basophils is due to mechanical shaking of the tissues.
- Aqua urticaria – has not previously been attributed to mechanical varieties of urticaria, but in recent years there have been indications that the physical effect of water jets is a provoking factor in this case. Activation of mast cells of the skin occurs by a non-immune mechanism and is rather weak, but with increased sensitivity of tissues to histamine, this leads to the development of erythema and itching.
In addition to mechanical factors, an imbalance of the cholineric vegetative nervous system can provoke the development of urticaria. This causes the development of so-called cholinergic urticaria. In addition to erythematous rashes and pruritus typical for this pathology, in this case there are also disorders of sweating, regulation of skin temperature. This type of urticaria is often provoked by a person’s emotional experiences.
In addition, pigment urticaria, having the character of an autoimmune pathology, is close to this skin disease. When it in the skin tissue accumulates an increased number of basophils, which can easily be activated by various factors.
Symptoms of allergic urticaria
Despite the huge variety of types of urticaria, and factors that can provoke it, the symptoms of the disease are quite monotonous and differ only in their severity. One of the first manifestations is the development of pruritus and redness of the skin.
Such phenomena can be both local and widespread, located symmetrically (with cholinergic type pseudoallergic urticaria) or, more often, asymmetrically. Very quickly (from several minutes to several hours) blisters of various sizes (0.2–5 cm) appear at the site of redness, which can merge with each other. An important diagnostic sign of allergic urticaria is painless blistering.
In most cases, these skin manifestations are resolved within 24 hours, leaving no traces behind them – provided that there is no repeated exposure to the provoking factor. Sometimes, with severe forms of allergic urticaria, the increase in symptoms occurs so rapidly that the rash on the skin develops into angioedema.
Preservation of skin manifestations and the development of new lesions indicates a continuation of the action of the provoking factor, which, in this case, may have an endogenous nature (as in the case of idiopathic urticaria).
Diagnosis of allergic urticaria
In clinical dermatology, the definition of this disease is made using a significant number of diagnostic techniques due to the large number of pathological forms. On examination, painless erythematous rashes, protruding above the skin surface, of various sizes and localization are detected.
Diagnosis of the acute form of allergic urticaria, especially if it is accompanied by any allergy, is made on the basis of the patient’s allergic history and determination of the level of immunoglobulin E in the blood. long-lasting rash there is a slight eosinophilia. By allergy tests you can identify the source of allergies and adjust the patient’s diet to prevent further attacks of the disease.
In those cases, if the rash does not disappear within 24 hours on the background of a hypoallergenic diet and exclusion of provoking physical factors, it is necessary to examine the lymph nodes, prescribe a general and biochemical blood test, conduct a urine test. All this will allow to identify the pathology, which may have become a triggering factor for the development of allergic urticaria, or to recognize the pseudo-allergic form of this condition in a timely manner.
Likewise, it should be done if the patient has a fever – the urticaria itself does not cause hyperthermia, but some infectious diseases can cause both symptoms.
Each type of pseudo-allergic urticaria (dermographic, cold, solar, etc.) is diagnosed by a metered exposure to a provoking factor. To do this, use a dermograph, ice cube, ultraviolet radiation with different wavelengths and other tools. Evaluation of the results, depending on the type of urticaria, the severity of symptoms and other factors is done in a few minutes or hours, the maximum period is 48 hours. A positive result of the test will be the development of erythematous rashes and pruritus in the study area.
Forecast and prevention of allergic urticaria
The prognosis of acute urticaria in most cases is favorable – the rash disappears within a day, leaving no marks on the skin. In the absence of repeated exposure to a provoking factor, the disease often never again disturbs a person. However, in the case of chronic forms of allergic urticaria, the prognosis largely depends on its type, severity, patient compliance with all the requirements of a dermatologist or allergist and the correctness of the prescribed treatment.
Such persons should always adhere to a hypoallergenic diet (eliminate eggs, chocolate, seafood and a number of other products from the diet). It is extremely important to identify the cause of skin disorders to minimize its impact. If the urticaria was provoked by another disease, then the prognosis largely depends on the success of its treatment.