Every Thing You should know about HIVES (Urticaria)
Hives (medical name: urticaria) is a common skin reaction to a wide variety of inciting agents. The rash consists of swollen, itchy wheals caused by the dilation of blood vessels and the escape of fluid from these vessels into the skin. The involved skin is usually bright red. The wheals may be very small or form large plaques; large areas may have bizarre, irregular outlines. Swelling of the soft tissues of the lips, face, or hands may produce large, thick areas that are slower to resolve. Itching is prominent and may be severe. Individual wheals almost always clear within one day, and frequently resolve within an hour or two. New wheals may continually arise, though.
Urticaria can be caused by medications, infections, food, nerves, or physical agents. Insect bites and stings often produce wheals or wheal-like bumps. Often, the exact cause cannot be determined, even after extensive investigation. Here we are primarily concerned with urticaria due to physical agents; physical urticaria occurs predominantly in young adults. The wheals subside within thirty minutes in all types, with the exception of pressure urticaria.
The following types of physical urticaria are described in this article.
1 . Dermographism
2. Pressure Urticaria
3. Cholinergic Urticaria (heat and exertion) 4. Aquagenic Urticaria
5. Cold Urticaria
6. Solar Urticaria
7. Direct Heat Urticaria
DERMOGRAPHISM
The term dermographism literally means "skin-writing", and in this condition one can literally write on the skin. Dermographism is the most common form of physical urticaria, affecting about 4 percent of young adults.! It mayor may not be associated with itching. Whealing occurs at the site of a scratch or scrape within 5 or 10 minutes, and usually fades in ten to fifteen minutes. The wheals may be induced by minor trauma, such as pressure from clothing, chair seats, clapping the hands, or enthusiastic kissing. Dermographism can occur after exercise or in association with widespread insect bites. This condition usually lasts for several months, and clears in many within one or two years.
PRESSURE URTICARIA
Pressure urticaria is fairly rare. It is characterized by deep, often painful swellings that develop four to six hours after pressure has been applied to the skin. The swelling lasts for eight to twenty four hours. Typically, it appears on the soles of the feet after standing for long periods.
CHOLINERGIC URTICARIA
After dermographism, cholinergic urticaria is the most common form of physical urticaria. Cholinergic urticaria may develop in response to exercise, heat, or emotional stress-sweating is the common denominator. Exercise is the most frequent precipitating factor and generally must be continued until sweating occurs for the wheals to appear. Usually there are bright red patches with scattered, small bumps. The small size of the wheals-a few millimeters in diameter-is characteri$tic. The rash appears within a few minutes and is gone withi11 thirty minutes. Intense itching is the rule, and sometimes occurs without the wheals.
AQUAGENIC URTICARIA
Aquagenic urticaria is rare. It resembles cholinergic urticaria in appearance but is produced by contact with water.
COLD URTICARIA
Cold urticaria is the third most common form of physical urticaria, after dermographism and cholinergic urticaria. In athletes, however, it is said to be the most common type of physical urticaria.2 The rash often begins abruptly, sometimes after an illness, or occasionally after venomous stings, infections, stress, or injections. Cold urticaria can be associated with underlying disease and one rare form is inherited. The disease is generally more common in females.
Minor degrees of whealing from cold exposure are common, while severe cases requiring medication are not. Usually only a few minutes of contact with cold are necessary. The wheals develop after the skin is rewarmed and fade after a period of thirty to sixty minutes. Itching without whealing can occur; this reaction most commonly results from immersion in cold water or contact with cold surfaces. Mucous membranes such as the mouth, tongue, and throat may be involved. In severe episodes, fainting may occur from generalized reactions and some swimmers have drowned.
Severe cold is often not required to produce whealing. Theimportant factor is a relative drop in temperature rather than a particular degree of cold. Exposure to cool winds or the evaporation of water from the skin may be sufficient to provoke whealing. However, some individuals observe facial swelling only after exposure to bitterly cold winds.
SOLAR URTICARIA
Solar urticaria is rare. The wheals develop within three minutes of sun exposure and begin to fade in fifteen to thirty minutes. Itching is usually associated. Exposed areas such as the face, forearms, and backs of the hands are often less sensitive than areas that are covered. If large areas of the body are involved, dizziness, wheezing, or collapse may result.
DIRECT HEAT URTICARIA
Rarely, wheals appear at the site if heat is directly applied to the skin.
Treatment and Prevention Guide for HIVES
Antihistamines have been used with variable success in treating the physical urticarias. In most cases they are useful, though the best ones require a prescription. They may be particularly helpful if taken one hour or more before engaging in an activity that is expected to produce whealing. If possible, one can avoid exposure to the physical agents which produce the urticaria. Persons with severe cold sensitivity should avoid swimming in cold water.
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