Urticaria is classified as more common skin conditions. Many of us, or at least someone we know, has experienced characteristic skin changes, which appear as pale red spots, which appear quickly and disappear rapidly. Dermatologists define urticaria as monomorphic (ie only one form changes manfiests) skin disease that is characterized by the appearance of wheals as primary efflorescences.
The mechanism of allergic urticaria occurrence
Urticaria occurs as type I allergic reaction, which means that the allergic reaction starts by binding antigens with antibodies. Antibody that binds to an antigen is typically attached to the surface of inflammatory cells such as mast cells and basophils which contain active chemical substances (e.g., histamine, serotonin, bradykinin). Chemically active substances mainly act so as to induce proliferation of capillaries, leading to the release of red blood cells from the capillaries (hence the redness) and “leak” of plasma through the capillaries.
Direct causes of hypersensitivity reactions
Those may be antibiotics (e.g., penicillin, sulfonamides) , vaccines, hormones (e.g. insulin), sedatives, house dust and many others. Other factors should be considered if they are present, such as diseases of the digestive system, local infection and even psychological factors.
In chronic urticarias, it is more difficult to find the cause of the changes than it is the case with the acute form of the disease.
How common is this disease?
This disease is one of the most common skin diseases, and is especially present with women of childbearing age. The changes are especially frequent if there is genetic predisposition, and these patients may have other signs of allergic hypersensitivity (e.g., asthma).
Appearance of wheals is typical, which quickly arise and disappear quickly, after which new wheals appear elsewhere. Wheal is a change in the skin with raised edges above the skin surface, and is differentiated from the surrounding skin with increased hardness (it cannot be folded) and color (pale red). The shape and size of rash is very different. The main subjective symptom of urticaria is itching that is not relieved by scratching but by pressure and kneading the wheals. Changes, in addition to the skin, can occur in other places. Edema of the glottis and larynx is especially dangerous, as it can lead to obstruction of the upper airways. Besides that, asthmatic seizures, edema of the joints and increased body temperature may occur.
Some of wheals are quickly formed and just as quickly disappear or reappear elsewhere. With changes lasting up to a month, the state is called acute, while changes that persist over a long period are called chronic.
The diagnosis is based on anamnesis, that is, on the characteristic and recognizable clinical presentation and prick tests. Radioimmunosorbent tests (RIST) are also occasionally considered.
Treatment of acute urticaria
Prior to the start of drug therapy it is necessary to remove the main cause – the antigen, if we know what it is. Antihistamines are the drug of choice, while in more severe conditions corticosteroids may be given. As a means to reduce exudate (i.e. swelling) calcium preparations may be consumed.
Systemic therapy is much more important than local one.
Treatment of chronic urticarias
Occasionally the disease requires a more complex treatment. The primary treatment is similar as in acute forms of the disease: before the start of drug therapy it is necessary to remove the main cause – the antigen, if we know what it is. Antihistamines are the drug of choice, while in more severe conditions corticosteroids may be given. As a means to reduce exudate (i.e. swelling) calcium preparations may be consumed.
Since it is suspected that a common cause of chronic forms of the disease lies in disorders related to the digestive tract, specific therapy attempts to alter the composition of the existing flora in the intestine with antibiotics and antimycotics. In addition, a diet can be recommended so that food that is the initial cause of the allergic reaction is avoided.
The prognosis is good in most cases, because the disease is not threatening with major complications, and only rarely acute risk of death can occur mainly from suffocation.