Heat exhaustion happens when your body overheats and can’t cool itself down. It usually results from physical activity in hot weather. Symptoms include dizziness, confusion and nausea. They usually improve by drinking water and resting in a cool place. Untreated, heat exhaustion can lead to heatstroke, a life-threatening condition.
Heat exhaustion happens when your body overheats (gets too hot) and can’t cool itself down. Your body can overheat during exercise or any physical activity, especially in hot, humid weather.
During physical activity, your body loses fluids through sweat. If you don’t replace those fluids by drinking water or other liquids, you can become dehydrated. Dehydration can also put you at risk for heat exhaustion.
Symptoms of heat exhaustion can include dizziness, headache, nausea, muscle cramps and others. Treatment includes removal from the heat, rest and fluids. Untreated, heat exhaustion can lead to heatstroke, which can be a life-threatening condition.
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Heat exhaustion and other types of heat illness (hyperthermia) are more common than you might think. Heat exhaustion from exercise happens more often on hot, humid days. Risk factors of heat exhaustion include:
Symptoms of heat exhaustion may develop slowly or appear suddenly. Before heat exhaustion symptoms appear, you may develop a red rash (heat rash) or heat cramps. These painful muscle cramps can affect any muscle, but they usually happen in the arms or legs.
Heat exhaustion symptoms may include:
Usually, your sweat cools your skin and acts like an air conditioner for your entire body. When you’re active (especially in hot weather), your body works hard to regulate its core temperature. Heat exhaustion happens when your body temperature rises too high and your body can’t cool itself down.
During physical activity, your body loses fluids and electrolytes through sweat. Electrolytes are minerals (such as sodium and potassium) that help your body work the way it should. If your body loses too much fluid and sodium (salt) and you don’t replace them, you become dehydrated. Dehydration can lead to heat exhaustion.
Usually, healthcare providers diagnose heat exhaustion with a physical examination. Your provider will examine you, take your temperature and ask about your recent activity. If your provider thinks you may have heatstroke, they may order blood and urine tests.
If you or someone you know has signs of heat exhaustion, it’s important to take action right away. You should:
To prevent heat exhaustion, you should:
Heat exhaustion symptoms usually go away after drinking fluids and resting in a cool place. It’s essential to get to a cool place and replace fluids as soon as possible to prevent serious complications.
Untreated, heatstroke can result from heat exhaustion. Heatstroke is a serious, life-threatening condition. It can cause brain damage, organ failure and death.
If you or your child has signs of heat exhaustion that don’t get better after about an hour of fluids and rest, you need immediate medical care.
Get help right away if you or someone you know:
A note from Cleveland Clinic
Heat exhaustion is a serious type of heat illness. Untreated, it can lead to severe health problems and death. If you or your child has signs of heat exhaustion, it’s essential to rest in a cool place and drink plenty of water. Seek immediate medical care if symptoms don’t get better after about an hour. To prevent heat exhaustion, stay hydrated, especially if you’re exercising in hot weather. Listen to your body if you feel thirsty or weak, and take breaks to let your body rest.
Last reviewed by a Cleveland Clinic medical professional on 03/03/2021.
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