Cholinergic urticaria is a relatively common disorder of the immune system characterized by an immediate skin reaction (hypersensitivity) to heat, emotional stress, and/or exercise. Symptoms of the disorder include the appearance of distinctive small skin eruptions (hives) with well-defined borders and pale centers, surrounded by patches of red skin (wheal-and-flare reaction). These red areas are typically intensely itchy (pruritus). Occasionally, cholinergic urticaria may be associated with systemic symptoms such as fever and/or difficulty breathing.
The symptoms of cholinergic urticaria may develop due to the reaction of specific immune system antibodies (IgE) to certain antigens, leading to a hypersensitivity response (Type I) and the wheal-and-flare reaction that is typical of cholinergic urticaria.
The symptoms of cholinergic urticaria occur in association with exercise, hot showers, sweating, and/or anxiety. Symptoms include the appearance of extremely itchy, small circular hives (pruritic urticaria) that have well-defined borders and pale (blanched) centers. Areas around these skin lesions become intensely red (wheal-and-flare reaction). Small hives occur most frequently on the upper back, upper arms, and/or neck and may last for minutes or up to an hour. Urticarial lesions may come together (coalesce) to form larger red areas, giving the skin a “blushed” appearance.
Some individuals with cholinergic urticaria may have swelling (angioedema) of the eyelids, lips, hands, and/or feet. A small number of people with cholinergic urticaria may also experience a variety of systemic symptoms including abdominal cramps, flushing, diarrhea, faintness, general weakness, asthma, and/or excessive sweating (hyperhidrosis).
Cholinergic urticaria is a disorder of the immune system characterized by a hypersensitivity reaction (IgE-mediated) to environmental factors that raise skin temperature and cause sweating. These include hot baths, warm rooms, exercise, and/or direct exposure to the sun. Other irritants in some cosmetics or drugs may also contribute to this hypersensitivity reaction. Eating hot foods, over-excitement, stress, and/or anxiety may also cause an episode of symptoms. Some scientists believe that some affected individuals may be hypersensitive to abnormally elevated levels of a substance in the body that transmits nerve impulses (the neurotransmitter acetylcholine).
The symptoms of cholinergic urticaria may develop due to the reaction of specific immune system antibodies (IgE) to certain antigens. This reaction causes the release of chemicals (i.e., Substance P or other neuropeptides), leading to the hypersensitivity response (Type I) and wheal-and-flare reaction that is typical of cholinergic urticaria.
Cholinergic urticaria is an immunological disorder that affects males and females in equal numbers. This disorder is fairly common; urticaria and angioedema affect about 20 percent of the general population at some time. Of these people, about 4 to 5 percent are believed to have cholinergic urticaria.
The symptoms of cholinergic urticaria begin most frequently between the ages of 20 and 39 years. Recurrent episodes of symptoms usually last for less than 6 weeks. However, when symptoms last for more than 6 weeks, they are considered chronic. Repeated episodes of hives may persist for months or years and then tend to improve on their own (spontaneously).
The diagnosis of cholinergic urticaria may be confirmed by a thorough clinical evaluation including specialized tests that induce the development of hives (urticarial wheals). About 30 percent of people with this disease develop hives when a cholinergic drug such as nicotine or acetylcholine is injected directly into the skin (intradermal). A heat challenge, such as immersing an arm in warm water or exercising while wearing warm clothing, may also help to confirm the diagnosis of cholinergic urticaria. During a systemic attack of cholinergic urticaria, the level of histamine may be elevated in the fluid surrounding the skin lesion (plasma histamine).
Hydroxyzine hydrochloride (Atarax) is the drug of choice for the treatment of cholinergic urticaria. The drug ketotifen, an H1 histamine- receptor antagonist, has been used to treat people with severe cases of cholinergic urticaria. Anticholinergic drugs are not usually effective at tolerable doses. Other common antihistamines such as benadryl may reduce skin redness and itching in some affected individuals. The application of benzoyl scopolamine cream to the skin (topical) may prevent the appearance of new skin lesions during an attack.
Some people with cholinergic urticaria may avoid episodes of symptoms by wearing protective clothing (e.g., a hat or long-sleeved shirt), applying sunscreens to exposed areas of skin, avoiding direct sunlight, and staying in a cool well-ventilated environment to minimize sweating. Repeated episodes of hives may persist for months or years and then tend to improve spontaneously. Other treatment is symptomatic and supportive.
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Second generation investigational antihistamines are also being studied for the treatment of cholinergic urticaria. Drugs such as cetirizine and acrivastine may help to decrease the severity of symptoms and to improve breathing difficulties that may occur in some rare cases. More studies regarding safety and long-term effectiveness are needed before these drugs may be recommended as a standard therapy for cholinergic urticaria.
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