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Overview

Urticaria, or hives, is a relatively common skin condition that is characterized by red, itchy welts of various sizes. Between 10 and 20 per cent of the population have at least one outbreak of hives in their lifetime. In most cases, hives are harmless and can be easily treated with medications. In rare cases, they can be life threatening.

If you get a single attack of hives, there is a good chance it was caused by a viral infection. However, some people get repeated attacks that are triggered by a variety of allergens, including drugs, foods, insect bites, inhaled substances, or latex. Others develop hives in response to sunlight, cold, heat, stress, or exercise. A case of hives that lasts longer than 6 weeks is known as chronic urticaria. There is usually no discernable cause, other than the possibility that the person's immune system may be oversensitive.

Symptoms of hives include itching, followed by swelling and redness. Welts can remain for anywhere from several hours to 24 hours, then fade away, only to appear later in another area. They can be the size of a pea or join together to cover larger areas of the body and penetrate deeper into the skin. This condition is called angioedema. It may include severe swelling of the eyes, mouth, hands or genitals, which looks frightening but is usually easily treatable. In severe cases where a person is extremely allergic to a specific food or drug, normal breathing or swallowing can be blocked and emergency measures must be taken. There is also an inherited but rare version of this condition called hereditary angioedema which can cause swelling in the airways, such as the larynx, tongue and throat.

Antihistamines are used to relieve swelling and itching. Taking a bath or shower can also help make hives go away if they have been caused by skin contact with an allergen, such as pollen or animal dander. If the hives are caused by a known allergen, your doctor will tell you to avoid that allergen as much as possible. If swelling is severe, you may be prescribed a corticosteroid, which is taken orally. When swelling affects a person's ability to breathe, they need emergency treatment, which includes antihistamines and possibly an injection of epinephrine to open the airways.

Prevention

You can prevent hives by avoiding allergens that may trigger an attack.