Cholinergic urticaria is a subcategory of physical urticaria ( hives) that is a skin <span style = 'background-color: #dae8f4'>rash</span>
brought on by a hypersensitive reaction to body <span style = 'background-color: #dae8f4'>heat</span>
. Symptoms follow any stimulus to sweat such as exercise (sometimes called exercise-induced urticaria), heat
from the sun (which could also indicate solar urticaria), saunas, hot showers.
The visible hives (sometimes called heat
bumps) appear as a multitude of small 2-3 mm welts typically surrounded by patches of red skin.