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.