Heat stroke is caused by prolonged exposure to high temperatures or by doing physical activity in hot weather. You are considered to have heatstroke when your body temperature reaches 104 F (40 C) or higher. High humidity, certain health problems and some medications increase your risk of heatstroke. So does being a young child or older adult.
Heat stroke is the progression of two worsening heat-related conditions. When your body overheats, you first may develop heat cramps. If you don’t cool down, you may progress to symptoms of heat exhaustion, such as heavy sweating, nausea, lightheadedness and feeling faint.
Heat stroke occurs if your body temperature continues to rise. At this point, emergency treatment is needed. In a period of hours, untreated heatstroke can cause damage to your brain, heart, kidneys and muscles. These injuries get worse the longer treatment is delayed, increasing your risk of serious complications or death.
Heat stroke symptoms include:
- High body temperature. A body temperature of 104 F (40 C) or higher is the main sign of heatstroke.
- A lack of sweating. In heatstroke brought on by hot weather, your skin will feel hot and dry to the touch. However, in heatstroke brought on by strenuous exercise, your skin may feel moist.
- Nausea and vomiting. You may feel sick to your stomach or vomit.
- Flushed skin. Your skin may turn red as your body temperature increases.
- Rapid breathing. Your breathing may become rapid and shallow.
- Racing heart rate. Your pulse may significantly increase because heat stress places a tremendous burden on your heart to help cool your body.
- Headache. You may experience a throbbing headache.
- Confusion. You may have seizures, hallucinate, or have difficulty speaking or understanding what others are saying.
- Unconsciousness. You may pass out or fall into a state of deep unconsciousness (coma).
- Muscle cramps or weakness. Your muscles may feel tender or cramped in the early stages of heatstroke, but may later go rigid or limp.
Heat stroke follows two less serious heat-related conditions:
- Heat cramps. Heat cramps are caused by initial exposure to high temperatures or physical exertion. Signs and symptoms of heat cramps usually include excess sweating, fatigue, thirst and cramps, usually in the stomach, arms or legs. This condition is common in very hot weather or with moderate to heavy physical activity. You can usually treat heat cramps by drinking water or fluids containing electrolytes (Gatorade or other sports drinks), resting and getting to a cool spot, like a shaded or air-conditioned area.
- Heat exhaustion. Heat exhaustion occurs when you don’t act on the signs and symptoms of heat cramps and your condition worsens. Signs and symptoms of heat exhaustion include a headache, dizziness or lightheadedness, nausea, skin that feels cool and moist, and muscle cramps. Often with heat exhaustion, you can treat the condition yourself by following the same measures used to treat heat cramps, such as drinking cool, nonalcoholic beverages, getting into an air-conditioned area or taking a cool shower. If your symptoms persist, seek medical attention immediately.
When to see a doctor
If you think a person may be experiencing heatstroke, seek immediate medical help. Call 911 or your local emergency services number.
Take immediate action to cool the overheated person while waiting for emergency treatment.
- Help the person move to a shaded location and remove excess clothing.
- Place ice packs or cold, wet towels on the person’s head, neck, armpits and groin.
- Mist the person with water while a fan is blowing on him or her.