The term urticaria refers to an allergic reaction of the skin, which is manifested by the discharge of pustules (often described as petals or candelas) and is accompanied by intense itching (itching). Etymologically, the term urticaria is derived from the word kneidi, which in ancient Greek means nettle. Contact of the skin with nettle causes itching and, locally, the appearance of bumps. For this reason, the condition is referred to as urticaria.

The rash of urticaria is transient, clearly circumscribed, raised in relation to the surface of the skin, temporarily subsiding on pressure. It has a pale center and is formed in the upper layers of the skin and leaves no marks when it subsides. Sometimes, it is accompanied by angioedema, i.e. swelling, usually of the lips, eyelids and ear flaps. It is migratory in nature, i.e. the rashes complete a cycle of ecchymosis- recurrence within a few (<24) hours and then appear and disappear, in the same way, in other parts of the body.

While the acute form of urticaria lasts, by definition, up to 6 weeks, the chronic form requires a duration of rash flares and remissions of more than 6 weeks. The 6 week time limit has been arbitrarily set, but is intended to help in the classification and etiological investigation of urticaria.

Unlike acute urticaria, which is a common condition, with 15-25 % of the general population experiencing at least one episode during their lifetime, chronic urticaria affects only 1 % of the population. That is, 1 in 10 who develop acute urticaria eventually develops into the chronic form. It mainly affects adults, roughly equally between men and women. However, chronic urticaria is not associated with an increased likelihood of developing allergic diseases and anaphylaxis, compared to the general population.

In chronic urticaria there is repeated exposure to the causative, triggering agent responsible for the condition. The symptomatology continues to reproduce as long as the underlying cause is not identified and treated. However, in reality, the culprit is identified in only 50% of cases.

Categories of chronic urticaria:

1. Autoreactive or autoimmuneComprises about 40% of chronic urticaria. It is a result of the interaction of the body's defences (autoantibodies) with elements of the body itself. It is usually found in patients suffering from an autoimmune disease. An indispensable element in the diagnostic approach is the performance of an autologous serum skin test.

2. SecondaryThis accounts for about 10% of cases of chronic urticaria. It is associated with the coexistence of conditions such as thyroiditis, chronic hepatitis, parasitic infections, chronic sinusitis, Helicobacter pylori infection. In general, chronic infections from bacteria, viruses, parasites or fungi may be responsible for the development of chronic urticaria.

3. Idiopathic:Diagnostic approach and clinical reasoning fail to identify the exact cause in about 50% of cases of chronic urticaria. In these cases the urticaria is classified as idiopathic.

In general, it should be understood that chronic urticaria is an unpredictable condition, with periods of flares and remissions, which may disappear as suddenly as it appeared.

4. Natural causes:The influence of physical factors, such as mechanical irritation, heat, cold, pressure and, less frequently, sunlight and contact with water, can be associated with symptomatology of chronic urticaria. Collectively these are referred to as natural hives.

It should be clarified that foods very rarely cause chronic urticaria and strict diets of avoidance of certain foods are often mistakenly followed. On the other hand, it is a fact that some foods have histamine or tyramine in increased content. Histamine is the main substance that causes the bumps, hence we take antihistamines to treat it. Therefore, eating large amounts of foods containing histamine will aggravate hives or may reduce the effect of antihistamines, but in no case are these foods responsible as allergens for hives.

The treatment of chronic urticaria, in principle, involves the identification and treatment of the underlying irritant or condition that may, etiologically, be associated with urticaria. In cases where no triggering agent is found, the treatment of choice is the administration of antihistaminic drugs, particularly those of the so-called second generation. These are safe drugs, which often need to be given in high doses and over a long period of time in order to control the symptoms.

If antihistamines are not enough, drugs that can be added are antileukotrienes (also safe drugs) and cyclosporine (has side effects). Corticosteroids can bring about remission (not cure) of the condition, but their short and limited administration during flare-ups is preferred due to adverse effects. Recently, a specific drug called omalizumab (Xolair) has been approved for the treatment of chronic urticaria with excellent results. Its possible administration is only on the recommendation of a specialist doctor.

The great importance of the therapeutic approach lies in the fact that chronic urticaria seriously affects the quality of life of patients. The very frequent psychological burden further exacerbates the appearance of new rashes, as nervous mechanisms 'activated' by stress also play an important role in the appearance of bumps.

Tasos Konstantinopoulos
ALLERGIST