Hives are reddish pink swellings or “wheals” that occur in crops on any part of the skin. Each wheal lasts a few hours before fading away, leaving no trace. New hives may continue to develop as old ones fade. They can vary in size from as small as a pencil eraser to as large as a dinner plate and may join together to form larger swellings. Hives are usually very itchy, but may also burn or sting.A natural chemical substance called Histamine is released from cells called “mast cells” which are found in the skin. A number of different things including allergic reactions, chemicals in foods, or medications can cause histamine release.
Hives usually disappear within a few days to a few weeks. Occasionally, a person will continue to have hives for many years. When hives form around the eyes or lips, the tissue may swell excessively. The term Angioedema is used to describe this type of swelling.
Acute Urticaria
Hives are classified according to how long the attacks last. The term “acute urticaria” is used for hives lasting less than six weeks. With this type of hives, the cause can usually be identified and eliminated. The most common cause of hives are certain foods, drugs or infections. Insect bites and certain internal diseases may also be responsible. Other causes can be physical stimuli, including pressure, cold and sunlight.
Foods
The most common foods that cause hives are nuts, chocolate, fish, tomatoes, eggs, fresh berries and milk. Fresh foods cause hives more often than cooked foods. Food additives and preservatives may also be responsible occasionally. Hives may appear within minutes or up to two hours after eating offending food(s).
Drugs
Almost any drug (medicine) or over-the-counter medication can cause hives. Common offending drugs include antibiotics, (Penicillin), pain medications (Aspirin), sedatives, tranquillisers and diuretics. Antacids, vitamins, eye and ear drops, laxatives, vaginal creams or any other non-prescription item can be a potential cause of hives. If one has an attack of hives, it’s important to tell one’s doctor about all of the medicines that one takes to assist him/her in finding the cause.
Infections
Certain infections can cause hives. Viral upper respiratory tract infections are a common cause in children. Other viruses such as Hepatitis B may also cause hives. Bacterial and fungal infections occasionally cause hives.
Chronic Urticaria
Bouts of hives lasting more than six weeks are called Chronic Urticaria. The cause of this type of hives is usually much more difficult to identify than that of Acute Urticaria. Your doctor will need to ask numerous questions in an attempt to find the possible cause. Since there are no specific tests to determine the cause of hives, testing will vary depending on one’s medical history and findings on clinical examination by the doctor.
Physical Urticarias
Certain people can develop hives from sunlight, cold, pressure, vibration or exercise. Hives due to sunlight are called Solar Urticaria. Reaction to the cold is more common. Hives appear when the skin is warmed after exposure to cold. If the exposure to cold is over large areas of the body, large amounts of histamine may be released which can produce wheezing, flushing, generalised hives and fainting. Cholinergic urticaria is tiny bumps surrounded by a white or red halo which come on with exercise, heat or emotion. These bumps itch intensely. Anything which raises the skin temperature can cause these tiny hives – sweating, sunlight, hot baths, blushing or anger.
The most common of the physical urticarias is called Dermatographism. Hives form from firmly stroking or scratching the skin. These hives may be very itchy.
Cold Urticaria [read more]
Treatment
The ideal treatment for hives is to determine cause and then eliminate it. Unfortunately, this is not always an easy task. While investigating the cause of hives, or when a cause cannot be found, antihistamines are usually prescribed by your dermatologist to provide some relief. Antihistamines work best if taken on a regular schedule to prevent hives from forming.
Antihistamines have previously been prescribed to take at night. But because of the side-effect of causing drowsiness, new less-sedating antihistamines are now available. The advantage of these new antihistamines is that they can be taken during the day without causing drowsiness.
Copyright Allergy Society of South Africa
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