Hyperthermia is the general name given to a variety of heat-related illnesses in which your body has become too hot. Examples of hyperthermia are heat exhaustion and heat stroke caused by a prolonged exposure to the sun or very high temperatures. Heat stroke can be life threatening and requires immediate medical care. A person with heat stroke usually has a body temperature above 104 degrees Fahrenheit. Other symptoms include confusion, combativeness, bizarre behavior, faintness, staggering, strong and rapid pulse, and possible delirium or coma. High body temperature is capable of producing irreversible brain damage. Fatigue, nausea and dizziness are some symptoms of hyperthermia, or overheating. Weakness, nausea and vomiting are other common symptoms of the condition.