Clinical Definition

Heat exhaustion is a reaction to prolonged exposure to high temperatures. It develops due to a depletion of electrolytes and dehydration without adequate replenishment. It is characterized by weakness, prostration and tachycardia. If heat exposure is allowed to continue, the condition may progress into heat stroke.

In Our Own Words

Normally, your body has a number of ways of cooling itself even in hot weather, which keeps the core temperature from rising. Heat exhaustion is a sign that your body is running out of tricks to keep cool, and it can develop as a result of continued exposure to heat if fluids lost through sweating are not replaced at adequate levels.

Sweating depletes the body of water and salt. When water consumed does not replace the fluid lost, the body may produce heat faster than it is released, and heat exhaustion may develop. Along with water, salt is also lost in sweat and needs to be replaced if excessive perspiration occurs. If the body’s cooling mechanisms continue to be overwhelmed, heat exhaustion can progress into heat stroke, which is a life threatening medical emergency.