different kinds of heat illness
Heat-Related Illnesses (Heat Cramps, Heat Exhaustion, Heat Stroke) Exposure to abnormal or prolonged amounts of heat and humidity without relief or adequate fluid intake can cause various types of heat-related illness. Children and teens adjust more slowly than adults do to changes in environmental heat. They also produce more heat with activity than adults, and sweat less.
Heat-related illnesses produce a high body temperature because the body cannot transfer heat effectively or because external heat gain is excessive. Heat-related illnesses include: Heat rash (prickly heat), which occurs when the sweat ducts to the skin become blocked or swell, causing discomfort and itching.
1 Heat tetany (hyperventilation and heat stress), which is usually caused by short periods of stress in a hot environment.  Heat syncope (fainting), which occurs from low blood pressure when heat causes the blood vessels to expand (dilate) and body fluids move into the legs because of gravity.