cholinergic urticaria [Gk, chole + ergon, to work; L, urtica, nettle] , an abnormal and usually temporary vascular reaction of the skin, often associated with sweating, in susceptible individuals subjected to stress, strong exertion, or hot weather. The condition is characterized by small, pale, itchy papules surrounded by reddish areas. It is caused by the action of acetylcholine on mast cells. Compare urticaria.
