Prickly heat is caused by the tiny sweat glands becoming blocked by profuse sweating. It is common in people exposed to
long periods of
heat and can develop as the result of high fevers.
Prickly heat is itchy and uncomfortable, but does not generally pose a health risk on its own. However, one form of prickly heat, miliaria profunda, so completely blocks the sweat glands that it can significantly increase heat related illnesses such as heat exhaustion or sunstroke.