What is urticaria?
Urticaria consists of itching and/or hives. Hives are pink swellings called “wheals” that can occur on any part of the skin. An individual hive will come and go within a 24 hour period. But, new hives may continue to develop as old ones fade. Hives can be as small as a pencil eraser or as large as a dinner plate and they can also join together to form larger swellings.
Is urticaria common?
Urticaria is very common. Ten to 20% of the population will have at least one episode in their lifetime. The condition usually spontaneously resolves in a few weeks to months. Occasionally, a person will continue to have urticaria for many years.
When hives form around the eyes, lips, or genitals, the tissue may swell excessively. Although frightening in appearance, the swelling usually goes away in less than 24 hours.
What causes urticaria?
Urticaria is caused by the release of histamine from mast cells. Mast cells are a type of cell in your body that lies along the blood vessels in the skin. So many things can cause your body’s mast cells to release histamine that it is often impossible to find out why histamine is being released and hives and/or itching is developing.
In the majority of cases, the cause of urticaria remains unknown. There are no specific tests to determine the cause of urticaria. Routine blood tests are most often of little or no value. If a cause of urticaria is identified, it is usually one of the following: foods, drugs, infections, insect bites, internal disease. Other causes can be pressure, cold, or sunlight.
The most common foods that cause hives are nuts, strawberries, chocolate, fish, tomatoes, eggs, fresh berries, and milk. Fresh foods cause urticaria more often than cooked foods. Food additives and preservatives may also be responsible.
Almost any prescription or over-the-counter medication can cause urticaria. Some of these include antibiotics (especially penicillin), pain medications, sedatives, and diuretics. Aspirin, antacids, vitamins, eye and ear drops or any other non-prescription item can be a potential cause of urticaria. Insulin injections and vaccines are another cause, as well as alcohol.
Many infections can cause hives. Viral upper respiratory tract infections are a common cause in children.
Certain people can develop hives from sunlight, cold, pressure, vibration or exercise, sweating, hot baths, blushing, or anger.