Urticaria is the medical term for hives — pale, red swelling or “wheals” that occur in groups on any part of the skin and usually last a few hours before fading without a trace. New areas of hives may develop as old areas fade. The hives can range in size from as small as a pencil eraser to as large as a dinner plate and may join together to form larger areas of swelling. Hives are usually itchy, but may also burn or sting.
Hives are very common. Between 10 and 20 percent of people have at least one episode in their lifetime. Hives are formed by the release of a chemical called histamine into the skin. Allergic reactions, chemicals in foods or medications can cause histamine release but sometimes the cause is impossible to find. Hives usually go away within a few days or weeks, but occasionally last for many years.
When hive form around the eyes, lips or genitals, swelling can be excessive and frightening; however, the swelling usually subsides within 24 hours.