Patient Information Urticaria

Cork Emergency Departments

Urticaria

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Urticaria (hives) are pale red swellings of skin 'wheals' that occur in groups on any part of the skin. Each individual skin lesion tends to last for a few hours before fading without trace. New areas of involvement may develop as other areas fade.

Patches of urticaria can vary in size from as small as the end of a pencil to as large as a dinner plate and they may join together to form larger swellings.

Urticaria is almost always itchy but it may also cause a burning or stinging sensation.

Urticaria is caused by leakage of the small blood vessels in the skin. This is caused by the release of a chemical called histamine within the skin. Histamine is released from specialised cells which lie along the blood vessels within the skin. Allergic reactions, chemicals in foods, medications and contact with irritant substances can cause histamine release. It is often impossible to find out exactly why urticaria has developed.

Urticaria is very common; approximately 10%-15% of the population will have at least one episode in their lifetime. Urticaria usually goes away within a few days but it can persist for several weeks.

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When urticaria forms around the eyes, lips, the genitals or on extremities, the tissue may swell excessively. Although this may appear frightening the swelling does usually go away in less than 24 hours.

The most common foods to cause urticaria are nuts, chocolate, fish, tomatoes, eggs, fresh fruits and milk.

Almost any prescription or over the counter medication can cause urticaria. Some of the most commonly implicated medications are antibiotics, analgesics, anti-inflammatories and diuretics (water tablets).

Many infections can cause urticaria, amongst them the common cold virus.

In some cases urticaria can be brought on by exposure to certain foods, sunlight, cold, pressure, vibration, exercise and some viral infections.

For individuals affected by the 'physical' urticarias the problem will usually be recurrent whenever the physical precipitating factor is present.

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Treatment

• The usual first-line treatment for urticaria is a prescription of anti-histamines. 
• Anti-histamine medications block the release of histamine and hence inhibits the development of the rash and its symptoms

In some cases more complex treatments are required.

In cases where urticaria is a recurrent problem (often triggered by physical stimuli) avoidance of the precipitating stimulus is recommended although not always practicable.