Feb
2008
“Hives“, medically known as “Urticaria“, are red, itchy, raised areas of skin that appear in varying shapes and sizes ranging from a few millimeters to several inches in diameter. They can be round, or they can form rings or large patches. Wheals (welts), red lesions with a red “flare” at the borders, are another manifestation of hives. Hives can occur anywhere on the body.
Hives tend to change size rapidly and to move around, disappearing in one place and reappearing in other places, often in a matter of hours.
Swelling deeper in the skin that may accompany hives is called ‘angioedema‘. This may be seen on the hands and feet as well as on mucous membranes.
Hives are produced by histamine and other compounds released from cells called mast cells, which are a normal part of skin. Histamine causes fluid to leak from the local blood vessels, leading to swelling in the skin. In rare cases, hives are found to be medically serious, 80% are idiopathic, which means that no cause could be manifested. Some hives are caused by allergies to foods, medications, and insect stings.
In rare cases, including some hereditary, others caused by bee stings or drug allergy, ‘urticaria’ and ‘angioedema’ are accompanied by shock and difficulty breathing. This is called anaphylaxis.
Almost all hives fall into two categories:
- Ordinary Hives (ordinary urticaria ),and
- Physical Hives (physical urticaria).
Ordinary hives flare up suddenly and usually for no specific reason and go within few minutes and last less than six weeks. The hives that last more than six weeks are often called “chronic.”
In most cases of ordinary hives, no cause is known. Others may be triggered by viral infections or caused by medications, like morphine, codeine, aspirin, and other non-steroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen), cause the body to release histamine and produce’ urticaria’ through non-allergic mechanisms.
Chronic hives can last from months to years. Allergy testing and laboratory tests are hardly ever useful in such cases.
The term ‘physical urticaria’ refers to hives produced by direct physical stimulation of the skin. By far the most common form is “dermographia,” which literally means “skin writing.” In dermographia, raised, itchy red welts with adjacent flares appear wherever the skin is scratched or where belts and other articles of clothing rub against the skin.
Another common form of physically induced hives is called ‘cholinergic urticaria’. This produces hundreds of small itchy bumps. These occur within 15 minutes of physical exertion, or a hot bath or shower happening more often in young people. Few might be triggered by cold, water, and sunlight.
The goal of treating most cases of ‘ordinary urticaria’ is to relieve symptoms while the condition goes away by itself. The most commonly used oral treatments are antihistamines, which may cause drowsiness.
Many antihistamines are available without prescription, such as diphenhydramine (Benadryl) and chlorpheniramine (Chlor-Trimeton) which can cause drowsiness, so often taken at bedtime. Among the over-the-counter used drugs are Loratadine (Claritin, 10 milligrams), cetirizine (Zyrtec, 10 milligrams), Claritin-D, Zyrtec-D. They are less likely to cause drowsiness.
Antihistamines that require a prescription include hydroxyzine (Atarax, Vistaril) and cyproheptadine, fexofenadine (Allegra) and levocetirizine (Xyzal). Sometimes physicians combine these with other types of antihistamines.
Oral steroids (prednisone, montelukast), ultraviolet radiation, antifungal antibiotics, and other agents that suppress the immune system, and tricyclic antidepressants (Amitriptyline, Elavil, Endep), nortriptyline (Pamelor, Aventyl), doxepin (Sinequan, Adapin), and some more topical therapies are also used in certain cases of hives.
To determine the kind of hives one has to understand certain important facts about the immune system, basic characteristics and symptoms of hives, and about some of the rarer forms of this disease. However, it is always better and advised to consult the physician.
It is also important, however, to keep in mind that most cases of this common disorder represent either ‘ordinary urticaria’ or ‘physical urticaria’, which are annoying but not serious or allergic, and almost always temporary.
