Causes

Heatstroke can occur as a result of:

• Exposure to a hot environment. In a type of heatstroke, called nonexertional (classic) heatstroke, being in a hot environment leads to a rise in core body temperature. This type of heatstroke typically occurs after exposure to hot, humid weather, especially for prolonged periods. It occurs most often in older adults and in people with chronic illness.
• Strenuous activity. Exertional heatstroke is caused by an increase in core body temperature brought on by intense physical activity in hot weather. Anyone exercising or working in hot weather can get exertional heatstroke, but it's most likely to occur if you're not used to high temperatures.

In either type of heatstroke, your condition can be brought on by:

• Wearing excess clothing that prevents sweat from evaporating easily and cooling your body
• Drinking alcohol, which can affect your body's ability to regulate your temperature
• Becoming dehydrated by not drinking enough water to replenish fluids lost through sweating