Decreased sweating; Anhidrosis
An abnormal lack of sweat in response to heat may be harmful, because sweating allows heat to be released from the body. The medical term for absent sweating is anhidrosis.
Anhidrosis sometimes goes unrecognized until a substantial amount of heat or exertion fails to cause sweating.
Overall lack of sweating can be life threatening because the body will overheat. If the lack of sweating happens in a small area only, it is usually not as dangerous.