Cholinergic urticaria is a type of skin rash that is triggered by sweating. The rash begins as a patch of tingling warm skin, and itchy red bumps develop within about half an hour. Cholinergic urticaria can be uncomfortable and aggravating, but it usually does not cause serious health problems. Taking oral antihistamines, wearing breathable clothing, and avoiding activities that cause excess sweating can help to reduce the frequency and severity of outbreaks.
Acute skin irritation related to cholinergic urticaria is considered a hypersensitivity reaction, similar to an allergic response. When sweat and heat are present on the skin, the body's immune system releases histamines that trigger inflammation. Potentially any activity or situation that causes sweating can cause a rash on a hypersensitive person. Hot weather, intensive exercise, constrictive clothing, and hot baths are common triggers.
The condition is most often seen in people between the ages of 10 and 30, but cholinergic urticaria can potentially arise at any age. Certain factors can increase the likelihood of developing skin rashes, such as being obese, living in a hot climate, and having severe asthma and allergies. In addition, many people who suffer from cholinergic urticaria have chronic skin problems such as eczema. Even without treatment, the condition usually decreases in severity and eventually goes away on its own over the course of several years.
Most people who have cholinergic urticaria develop rashes on their arms and chests. Rashes elsewhere on the body are possible but uncommon. When sweating occurs, a small patch of skin typically becomes warm and red. It may start to itch, tingle, or burn within minutes, and small hives begin to emerge. Individuals with severe hypersensitivity may experience headaches, chest pain, and breathing problems as their rashes worsen. In most cases, symptoms begin to disappear after about an hour as a person rests and cools off.
A person who experiences frequent skin rashes should visit a dermatologist to discuss treatment options. A doctor can ask about symptoms and perform allergy tests to determine if treatment for nasal allergies or asthma is needed. Most patients are prescribed antihistamines to take during acute attacks or daily as a preventive measure against cholinergic urticaria. In addition, topical creams may be prescribed to ease burning and itching.
A dermatologist can also help patients identify their triggers and learn how to avoid them. Changing or reducing exercise routines may help reduce the risk of recurring skin problems. Light, breathable, non-constricting clothing can help keep sweat off of the skin. It is not always possible to prevent all triggers, especially if a person lives in a hot climate, but taking all possible precautions against cholinergic urticaria can significantly reduce the frequency of episodes.