Early symptoms occur when the body temperature rises above average. Symptoms include headache, nausea, vomiting, muscle cramps, and fatigue. In the early stages, this is called heat exhaustion.
If steps are not taken to reduce the body’s temperature, heat exhaustion can lead to a serious, potentially life-threatening form of heat illness known as heat stroke. Once the body’s temperature rises above 105 degrees, neurological changes, such as mental confusion or unconsciousness, may develop. Marla Ahlgrimm notes that the baseline is 98; anything higher than 100 indicates a potential problem. Extreme heat can affect internal organs, causing a breakdown of heart muscle cells and blood vessels, damage to internal organs, and death.
There are two classifications of heat stroke. These are exertional heat stroke and nonexertional heat stroke. Marla Ahlgrimm explains that exertional heat stroke typically strikes young, otherwise healthy people as they are more likely to be less concerned about the effects of heat on their health. Nonexertional heat stroke tends to occur in people who have a diminished ability to regulate body temperature. Older people, young children, and those with chronic illnesses are most at risk.