Heat Stroke (Hyperthermia)

What Is It?

The human body usually can regulate its temperature. When the body gets too hot, it uses several strategies to cool down, including sweating. But if a person spends too much time in the heat without taking in enough fluids, the body's cooling processes can't work properly. When the body becomes dehydrated, it can no longer cool itself by sweating. When this happens, body temperature can rise high enough to make the person sick.

The first symptoms of heat illness occur as the body temperature climbs above normal, and can include headache, nausea, vomiting, muscle cramps and fatigue. These early symptoms sometimes are called heat exhaustion. If steps are not taken to reduce body temperature, heat exhaustion can worsen and become heat stroke.

Heat stroke is a serious, potentially life-threatening form of heat illness. The body temperature rises to 105 degrees Fahrenheit or higher and you develop neurological changes, such as mental confusion or unconsciousness. At these high temperatures, body proteins and the membranes around the cells in the body, especially in the brain, begin to be destroyed or malfunction. The extreme heat can affect internal organs, causing breakdown of the heart muscle cells and blood vessels, damage to internal organs, and death. There are two main causes of heat stroke:

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