There are three heat-related illnesses that hot weather exposure can produce. Heat stroke is life threatening. The victim's temperature control mechanisms stop working. The body temperature can rise so high that brain damage and death may occur if the body is not cooled quickly. First aid is to cool the person down as quickly as possible and call for medical help.
Heat exhaustion is less dangerous than heat stroke.
It typically occurs when people work in a warm, humid place where body fluids are lost through heavy sweating. First aid is to get the person in a cooler place, place him or her on their back with feet elevated. Heat Cramps are muscular pains and spasms due to heavy exertion. Heat cramps usually involve the abdominal muscles or the legs. It is generally thought that the loss of water and salt from heavy sweating causes cramps.