There are several types of heat illnesses
1.Heat Cramps- cramps in the muscles, caused by loss of water and certain minerals. Generally found in a person exercising.
2. Heat exhaustion is the next more severe- it is where your body cannot produce enough sweat to release the heat from your body. this happens to a person exercising in the heat.
3.Heat Stroke is the most severe- your body cannot regulate the temperature of itself. Again it can be seen in someone exercising in a hot enviroment, or in the elderly or infirmed. They must be treated in the ER.