If your body has to work extremely hard to cool you, you can develop a heat exhaustion. During heat exhaustion, the body's core temperature is usually less than 104 degrees Fahrenheit, but blood pressure is low and the heart is not pumping the blood as efficiently as it should.
At this stage, the body still does what it should. "They will be very tired and sweat a lot and thirsty – so these natural defenses against heat and dehydration will still work," says Peter Shearer, MD, Deputy Director of the Emergency Department at Mount Sinai Hospital in New York City.
Heat exhaustion does not necessarily lead to heat exhaustion ̵
Heat stroke causes a malfunction of the central nervous system. It can also damage the brain, heart, liver, kidneys, spleen and muscle tissue. "Your body loses the ability to regulate heat, and at that point, it's much harder to reverse yourself," Dr. Shearer.