Heat exhaustion is a result from a loss of water and salt in the body, according to Johns Hopkins Medicine. It occurs in conditions of extreme heat and excessive sweating without adequate fluid and salt replacement. It occurs when the body is unable to cool itself properly and, if left untreated, can progress to heat stroke.
What to do: Move to a cooler place, hydrate with water or a sports drink, and rest. If symptoms persist, seek medical attention.
Heat stroke is the most severe form of heat illness. It occurs when the body’s heat-regulating system is overwhelmed by excessive heat. It is a life-threatening emergency and requires immediate medical attention.
What to do: Call for emergency help immediately. While waiting for medical assistance, move the person to a cooler place, remove excess clothing, and apply cool, damp cloths to the body.

