Heat exhaustion occurs when your body loses excess water and salt, typically through sweating. On the other hand, heat stroke is a serious medical emergency that occurs when your body is unable to control its internal temperature.
As the weather gets warmer, we tend to spend more time outside under the hot sun. It’s important to know the difference between heat stroke and heat exhaustion.
Knowing the signs and symptoms of these two conditions could save your life or that of a loved one.
Symptoms related to heat stroke or heat exhaustion can be very serious. Muscle cramping may be the first sign of a heat-related illness. Other symptoms
| Symptom | Heat exhaustion | Heat stroke | What to do |
|---|---|---|---|
| general weakness | X | take a cool shower or use a cold compress to decrease body temperature | |
| elevated body temperature above 104°F (40°C) | X | call 911 for emergency treatment | |
| increased heavy sweating | X | hydrate with water or sports drinks | |
| rapid and strong pulse or heart rate | X | move to a shaded or cool area | |
| hot, red, dry, or moist skin | X | use a cold compress or cold, wet cloth to help lower body temperature | |
| loss or change of consciousness | X | circulate air to speed up cooling | |
| a weak but faster pulse or heart rate | X | move to a shaded or cool area | |
| nausea or vomiting | X | seek medical treatment if vomiting continues | |
| possible fainting, lightheadedness, dizziness | X | lie or sit down | |
| pale, cold, clammy skin | X | remove any extra layers or unnecessary clothing, like shoes or socks |
Keep in mind that heat stroke can be much more serious than heat exhaustion and requires immediate medical attention to prevent complications.
Both heat stroke and heat exhaustion are caused by your body’s inability to cool itself.
Sweat is your body’s natural way to cool you down. If you overexercise or work strenuously in hot weather or a heated room, your body may have difficulty producing enough sweat to keep you cool.
Other causes of heat exhaustion and heat stroke include:
- dehydration
- wearing heavier, tight clothing
- consuming alcohol
If you’re experiencing heat exhaustion for an extended period of time, it can lead to heat stroke. Heat stroke can come on quickly if it’s very hot or you’re overexerting yourself. That’s why it’s important to begin treatment at the first signs of heat exhaustion.
When does it become a medical emergency?
If you can cool down within 30 minutes, heat exhaustion isn’t typically considered an emergency.
But if you’re unable to lower your body temperature or if you experience any of the following symptoms, you should call 911 and seek immediate medical attention:
- seizure
- having a body temperature above 104°F (40°C)
- confusion
- loss of consciousness
- not sweating, even though you feel hot
- shortness of breath
- fast breathing
- excessive nausea or vomiting
Certain factors can increase your risk for heat exhaustion and heat stroke, though anyone can develop either condition.
The following factors can increase your risk for heat sensitivity:
- Age. Infants and children under the age of 4 and adults aged 65 and older are at increased risk for heat-related illnesses. That’s because your ability to regulate temperature is more difficult at these ages.
- Prescription medications. Some medications used to treat high blood pressure or heart conditions may reduce your ability to stay hydrated. Dehydration can cause heat exhaustion and heat stroke.
- Obesity. Your body retains more heat when you weigh more. It can also be more difficult to cool your body down if you are overweight or obese.
- Sudden temperature changes. When you rapidly move from a colder to a warmer climate, like going on vacation in a hotter location, your body may not be able to adjust to the warmer weather. You may have more difficulty regulating your body temperature as a result.
- A high heat index. The heat index is a measurement that factors in humidity along with the outdoor temperature to determine how hot it feels to you and your body. If the humidity is high, your sweat evaporates more slowly, making it harder to cool down. If the heat index is above 91°F (32.8°C), focus on prevention methods.
Taking your temperature can be beneficial if you’re experiencing any symptoms of heat-related illness. A temperature above 100°F (38°C) may indicate heat exhaustion, while a temperature above 104°F (40°C) is a sign of heat stroke.
However, this may be impractical if you’re outdoors and away from your home.
What to do if you’re experiencing heat illnessConsider these immediate actions:
- Seek medical attention immediately if you believe you’re having heat stroke.
- Leave the hot environment — going indoors, finding a cooler, shady place out of the sun and heat as much as possible.
- Drink water to hydrate. Avoiding any sugary or otherwise sweetened beverages that may not help with hydration.
- Tell someone how you’re feeling and call for help if you can’t manage on your own.
Your doctor will likely be able to diagnose heat exhaustion or heat stroke based on your symptoms, but they may decide to run tests to confirm the diagnosis or check for complications:
- A blood test may be used to check your sodium or potassium levels to help determine if you’re dehydrated.
- A sample of your urine may be taken. Dark yellow urine may be a sign of dehydration.
- Muscle function tests may be performed.
- Your doctor runs tests to check your kidney function.
- X-rays and other imaging tests can be used to determine if you have any internal organ damage.
If you begin experiencing symptoms of heat exhaustion, try to find a cooler location if possible. For example, if you’re outside, look for a shady area. If you’re indoors, remove a layer of clothing or turn on the air conditioning.
You may also want to lie down, or, if that isn’t possible, stop strenuous activities. That may help your body regulate temperature.
Drink water or a sports drink to help rehydrate yourself. Sports drinks have electrolytes, which your body loses through excessive sweating.
If you’re nauseated or start vomiting, seek help from a medical doctor right away.
A heat stroke is considered a medical emergency. Call your local emergency services immediately if you suspect that you’re having a heat stroke.
Your doctor may place you in a bath of cold ice water to lower your temperature quickly. They may also mist your skin with water, place ice packs on you, or wrap you in a special cooling blanket.
If the cold causes you to shiver, your doctor may prescribe medications to stop it. This might increase your body temperature.
With treatment, you can fully recover from heat exhaustion. Early intervention can also stop it from progressing to a medical emergency.
One of the main ways to prevent heat-related illnesses like heat exhaustion and heat stroke is to keep your body temperature cooler.
This is particularly important when you’re working or doing activities outside in the heat or sun.
Prevention tips
Here are some prevention tips:
- Stay hydrated. Drink 2 to 4 cups of water every hour when you’re doing activities outside in the heat or direct sunlight. Your body needs more water than usual when working in a hot environment because you’ll lose more fluids through sweating.
- Avoid alcohol or caffeinated beverages if you’re doing strenuous activities, especially in the heat. Caffeine increases your risk of dehydration.
- Stay inside in a temperature-controlled or air-conditioned environment. Try to avoid doing activities outside during the hottest parts of the day and in direct sunlight.
- Wear lighter clothing. Light-colored, loose, lightweight clothing for outdoor activities in the heat. A wide-brimmed hat will keep the sun from your face and help you stay cooler.
- Take cooler baths or showers on a hot day to help cool you down.
- Take frequent breaks when working or exercising in the heat. This includes activities like hiking or playing sports.
- Never leave children, infants, adults, or pets in a closed, parked car. The temperature inside a closed car can become very high, even if the outside temperature is mild. That can lead to heat-related illnesses.
- Planning ahead for hot-weather activities can help reduce your risk of heat exhaustion and heat stroke.
Heat exhaustion occurs when your body loses excess water and salt, typically through sweating.
Heat stroke is a serious medical emergency that occurs when your body is unable to control its internal temperature.
You can treat both and prevent heat-related illnesses to avoid them becoming more serious medical emergencies. You can also take several simple steps to avoid both of these.