What are Hives?
Hives are red, very itchy, swollen areas of the skin. Hives arise suddenly and may leave quickly in 1-2 hours, or can last as long as 24 hours. They often appear in clusters, with new clusters appearing as other areas clear. Physicians refer to hives as urticaria. Over 20% of the population has suffered an eruption of hives at some point in their lives.
What Causes Hives?
Often hives are a side effect from eating certain foods or taking medications. Foods likely to cause hives include nuts, tomatoes, shellfish, and berries. Medications often responsible for producing hives are penicillin, sulfa, anticonvulsant, phenobarbital, and aspirin.
What are Some Other Causes of Hives?
A common form of hives is dermatographism, which occurs in 5% of the population. The hives are caused by a constant stroking or rubbing of the skin, and often occur after scratching, or when tight-fitting clothes rub the skin.
Cholinergic urticaria (hives) is the medical profession's term for hives that can develop after activities which increase the body's temperature. Activities that can cause this include a warm bath, shower, jacuzzi or hot tub use, exercise, a fever, or emotional stress. It has been estimated that 5% - 7% of patients who have hives experience cholinergic urticaria.
Cold-induced hives occur after exposure to cold wind or water. Hives may appear on limbs and generally on any exposed area. Cold water or liquids can provoke symptoms on the lips or in the mouth.
Solar hives are caused by exposure to sunlight or to a sunlamp, and a reaction can occur within one to three minutes.
Exercise is another cause of hives. Some individuals affected can also develop lung obstruction and/or lose consciousness. Such a severe reaction is called exercise-induced anaphylaxis.
Sometimes hives will occur in individuals recurrently without an obvious cause. This is called chronic urticaria (hives). While mainly a nuisance and not associated with other serious internal disease, the exact mechanism for this condition is not known, and the hives usually disappear on their own.
What is Angioedema?
While hives develop on the skin's surface, angioedema is a swelling of the deeper layers of the skin. It most often occurs on the hands, feet and face. If the angioedema occurs in the throat, normal breathing or swallowing can be blocked, and emergency measures must be taken. This is a rare occurrence, since most angioedema causes swelling of the lips or eyes with no long-lasting effects. Hives and angioedema may appear together or separately on the body. Angioedema usually lasts one or two days and may reoccur with or without hives over an indefinite period of time.
Hereditary angioedema is a rare inherited disease which can be fatal in some cases, and in this respect differs from other types of chronic angioedema. Swelling can occur in the airways such as the larynx, tongue and throat, as well as on the face and other extremities. Swelling in the stomach area has led to severe pain and surgery for what was thought to be appendicitis. It has been demonstrated that a blood protein deficiency is the cause of this inherited illness.
How Can Hives Be Treated?
Avoiding the foods, drugs, or other provoking factors is recommended whenever possible. Antihistamines such as hydroxyzine, diphenhydramine, pyrilamine, terfenadine, cimetadine, and ranitidine are used to treat recurrent episodes. Use of these medications is recommended only under the guidance of your allergist.
Hydroxyzine is especially effective for the treatment of cholinergic urticaria. Cyproheptadine is used to treat cold-induced hives. If the hives do not respond to the antihistamines, many allergists will utilize corticosteroid medications such as prednisone, which are given in conjunction with the antihistamines. Most patients will improve with steroid treatment, but if possible, steroids should be avoided for chronic use. Nevertheless, some patients, especially those with chronic hives, may require them. After a suitable interval, the individual can then discontinue use of the steroid medications, since long-term therapy is not recommended. At that time, continued treatment with antihistamines is suggested until medication for the hives is no longer necessary.
In severe, acute cases where angioedema is involved, adrenalin injections may be necessary to alleviate the swelling. Hereditary angioedema can be very effectively treated with special hormone medications.
Your allergist can provide you with more information on hives.
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