Information on Urticaria

Urticaria, commonly referred to as hives, is the most frequent dermatologic disorder seen in the ED. It appears as raised, well-circumscribed areas of erythema and edema involving the dermis and epidermis that are very pruritic. Urticaria may be acute (lasting less than 6 wk) or chronic (lasting more than 6 wk). A large variety of urticaria variants exist, including acute immunoglobulin E (IgE)–mediated urticaria, chemical-induced urticaria (non-IgE-mediated), urticarial vasculitis, autoimmune urticaria, cholinergic urticaria, cold urticaria, mastocytosis, Muckle-Wells syndrome, and many others.

Urticaria refers to a group of disorders affecting adults and children, in which red patches and weals occur in the skin. The release of chemicals such as histamine from mast cells in the skin causes small blood vessels to leak and results in tissue swelling. The weals can be a few millimetres or several centimetres in diameter, coloured white or red, often surrounded by a red flare, and frequently itchy.

Causes

Urticaria is very common, especially in people who have experienced other allergic reactions. The eruptions usually occur in batches. Release of histamine and other chemicals into the bloodstream, associated with the allergic response, causes the itching, localized swelling, and other symptoms. Many substances, called allergens, can trigger the allergic response.

Symptoms

Raised red and white patches appear on the skin. They are accompanied by burning,intense itching, and stinging. Rubbing and scratching usually aggravate the condition. The outbreak of urticaria is sudden and the disease may affect any part or the entire body. The eruptions may be as small as pin heads or as large as a rupee. The eruption may fade in a few minutes or an hour in one place, but may appear in another.

Diagnosis

Usually its appearance, or a description of it, will be enough for your doctor to make the diagnosis. In the vast majority of people no cause can be found, though your doctor will ask you questions to try to identify one. There is no special test that can reliably identify the cause of urticaria, but some tests may be done if your answers suggest an underlying cause.

Treatment

The best treatment for urticaria is to find and eliminate the cause whenever possible. Antihistamines are prescribed to provide relief and work best if taken on a regular schedule to prevent hives from forming. There are many antihistamines available. No one antihistamine works for everyone. The dermatologist may use combinations to control the urticaria. In severe cases, an injection of epinephrine (adrenalin) may be needed. Cortisone may also bring dramatic relief, but its use must be limited to short periods of time.

Often it is handled just with limiting one's exposure to triggers such as strenuous exercise or heat. For some, the reaction can be limited by making sure to wear light breathable clothing allowing the body to remain cool. Also, gradually warming the body with light exercise first can help limit the effects in some people. Since an attack can often be felt coming on, it can sometimes be halted by rapid cooling, such as applying cold water or an ice pack to the skin.