Heatstroke vs. heat exhaustion: What's the difference?

Heatstroke and heat exhaustion are both conditions that can develop when you have spent prolonged periods of time in the heat. 

Heat exhaustion shows up when your body has lost a lot of water and salt due to increased sweating. If you have heat exhaustion and can cool down within 30 minutes, you typically won’t need emergency medical attention.

Heatstroke is a more severe condition that can occur when your body can no longer control its temperature. Your body temperature may go up to 106°F or higher within 10 to 15 minutes. You may also find that it is difficult for your body to cool down.

If you are concerned that you or someone you know may be experiencing a heat-related illness, it is important to seek medical help immediately.

Symptoms

Heat exhaustion and heatstroke symptoms can be similar, but heatstroke symptoms tend to be more severe. It is important to know that heat exhaustion may turn into heatstroke if it worsens.

Symptoms of heatstroke

Symptoms of heatstroke can include:

• high body temperature of around (104°F or higher)
• red, dry, hot, or damp skin or lots of sweating
• strong, fast pulse
• dizziness or confusion
• headache
• feeling sick
• seizures
• losing consciousness (passing out)
• anxiety

Whilst experiencing heatstroke, you may stop sweating, which can prevent your body from cooling down.

Heatstroke is a medical emergency. If it isn’t treated quickly, it can be fatal.

Symptoms of heat exhaustion

Symptoms of heat exhaustion include:

• lots of sweating
• pale, cold, and clammy skin
• weak, fast pulse
• feeling or being sick
• muscle cramps
• dizziness
• headaches
• fainting

If you have heat exhaustion, you should start to cool down and feel better within 30 minutes.

Treatment

Heatstroke is a medical emergency. You should call 911 straight away if you or someone you know may have heatstroke.

Treatment for heatstroke can include the following:

• sit the person in a cool place
• use cool cloths or a cool bath to lower body temperature
• do not try to give them water if they lose consciousness

Once in a hospital, a doctor will treat the heatstroke by ensuring you can breathe properly and that blood is moving through your body correctly. A doctor will then take steps to cool you down as quickly as possible.

In the case of heat exhaustion, you can usually take some steps yourself to cool down. This can include:

• moving to a cool place
• wearing loose clothes
• putting wet, cool cloths on your body or taking a cool bath
• sipping water

If you have heat exhaustion and your symptoms last longer than 1 hour or start getting worse, you should get urgent medical help.

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Prevention

The United Kingdom’s National Health Service (NHS) suggests that you can avoid heatstroke and heat exhaustion by:

• drinking regular cold drinks
• avoiding too much exposure to the sun 
• reducing how much alcohol you drink
• avoiding extreme exercise (especially in hot weather)
• wearing cool and light-colored clothing
• remaining in the shade during times of hot weather

It can be helpful to check in on older adults regularly when the weather is hot (especially if they don’t have air conditioning) and avoid leaving children in cars by themselves.

Risk factors

Some factors can make you more likely to develop heatstroke or heat exhaustion. These risk factors include:

• Age: Children and adults above 65 years old are more likely to develop heat-related conditions.
• Health conditions: If you have an underlying health condition like diabetes or a heart condition, you may be more likely to experience a heat-related illness.
• High temperatures: If you are in very high temperatures or humid environments, this can increase your risk of heat exhaustion and heatstroke. Suddenly going from a cool climate to a warm climate may also increase your risk of heat-related conditions.  
• Vigorous exercise: Intense exercise (especially in hot weather) can increase your risk of heat-related illnesses.
• Dehydration: If you are not drinking enough fluids or you are sweating a lot, you may be more at risk of heat exhaustion or heatstroke.
• Medications: Some medications, like diuretics or antidepressants, may change how your body reacts to heat.
• Alcohol: Alcohol can affect your hydration levels. It can also affect your judgment, and you may forget to take some of the steps that can protect you against heatstroke.

Summary

Heatstroke and heat exhaustion can both develop when your body gets too hot. Heat exhaustion can cause symptoms such as:

• sweating
• dizziness
• headaches
• nausea

You can usually manage heat exhaustion yourself by using different strategies, such as moving to a cool place or sipping water to cool down.

Heatstroke is a more serious condition that can develop when your body can no longer control its temperature and overheats. If you are concerned that you or someone else may have heatstroke, it is important to seek medical help immediately.

You can take steps to prevent heatstroke and heat exhaustion. It can help to make sure that you are drinking plenty of water, staying cool and out of the sun, and avoiding intense exercise in hot weather.

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