What Are Signs and Symptoms of Heat Stroke?
Nearly 200 million Americans have been under extreme heat alerts this summer, with temperatures breaking record highs across much of the U.S.
While it might feel like the perfect time to enjoy a pool day, it’s also a time to pay close attention to your body’s responses. When the temperature spikes, it’s easy to overheat, and that can quickly become dangerous.
Keep reading to learn what heat stroke is, common signs to look for, and what to do if you or someone near you is suffering from heat-related illness.
Key takeaways:
Heat stroke is a life-threatening emergency.
It happens when your body overheats and can’t cool down fast enough, leading to a rapid rise in internal temperature.
If untreated, heat stroke can cause serious damage to your brain, heart, and other organs.
Signs and symptoms include a core body temperature of 104 degrees Fahrenheit or higher, confusion or slurred speech, rapid heartbeat, hot and dry skin, headache, and dizziness.
What is Heat Stroke, and Is It an Emergency?
Heat stroke is a medical emergency. It’s the most severe form of heat-related illness and it happens when your body’s internal temperature climbs to dangerously high levels–typically 104 degrees Fahrenheit or higher.
When this happens, your body’s natural cooling system–sweating–can’t keep up. As a result, your brain, heart, kidneys, and other vital organs can start to overheat and break down under the stress.
Unlike heat exhaustion, which usually improves with rest and hydration, heat stroke can be life-threatening. It requires immediate medical care to prevent serious complications, including permanent organ damage or even death.
It’s more common in:
People with chronic health conditions, such as heart or kidney disease
People who work or exercise outdoors
But it can happen to anyone, especially during the kind of extreme heat many states in the U.S. are seeing now.
If you're spending time outdoors this summer, taking a few simple precautions can help you stay safe–starting with knowing the signs of heat stroke.
What Are the Signs and Symptoms of Heat Stroke?
Heat stroke can come on suddenly, especially in hot, humid conditions or during intense physical activity. And symptoms tend to be more severe than general heat sickness.
These are some of the most common early red flags:
Confusion, disorientation, or slurred speech
Rapid heartbeat
Shallow breathing
Hot, dry skin that may feel flushed (sweating often stops, although not always)
Headache or dizziness
Nausea or vomiting
Loss of coordination or fainting
Seizures or loss of consciousness in severe cases
Again, heat stroke is a medical emergency. So if you notice these signs in yourself or someone else, act fast by calling 911.
Heat Stroke vs. Heat Exhaustion
Heat exhaustion is a less severe form of heat-related illness, but it can progress into heat stroke if untreated. Its primary symptoms include:
Mild confusion
Pale or clammy skin
Heavy sweating
Headache
Nausea
Muscle cramps
Fatigue or weakness
Dizziness or lightheadedness
The main difference is the severity of symptoms. With heat exhaustion, you’ll likely still be sweating and somewhat alert.
When the body’s cooling mechanisms start to fail (leading to dry skin, disorientation, or fainting), it’s moved into heat stroke territory and requires emergency care.
What Should You Do for Heat Stroke?
If you or someone near you starts to show signs of heat stroke, take these actions immediately:
Step 1: Call 911 or Seek Emergency Care
Heat stroke can cause permanent damage and may even be fatal if untreated. Call 911 right away, especially if the person is confused, having a seizure, or otherwise deteriorating quickly.
Step 2: Move to a Cooler Environment
Get out of the heat and into an air-conditioned space if possible. If that’s not available, find the nearest shady area or position the person in front of a fan.
Step 3: Start Cooling the Body
While you wait for help:
Apply cool (not ice-cold) water to the skin or mist with a spray bottle. Some studies suggest that extreme cold can constrict blood vessels, trapping heat inside the body instead of helping it escape.
Use cool compresses on the person’s cheeks, neck, underarms, hands, groin, and/or feet.
Remove excess clothing if possible.
Fan the person or increase airflow.
If the person is alert and able to swallow, offer small sips of cool water. Don’t give anything to drink if the person is vomiting, drowsy, or not fully coherent.
What Not To Do
Don’t give caffeine or alcohol. These can further dehydrate the person, worsening symptoms.
Don’t use ice baths unless directed by a medical professional (they can cause shock in some cases).
Don’t wait it out thinking it will pass. Heat stroke always needs medical attention.
Even if symptoms improve after cooling down, it’s still critical to seek medical care to check for any internal complications.
How Long Does Heat Stroke Last?
The most intense symptoms of heat stroke can last from a few hours to a few days, depending on how quickly treatment starts. Many people begin to stabilize within 24 hours, but recovery can take longer. Here’s what to expect.
Short-Term Recovery
After emergency care, people often experience:
Fatigue or weakness
Sensitivity to heat or sunlight
Brain fog or forgetfulness
Low appetite or slight nausea
These symptoms typically improve over several days to a week, especially with rest, hydration, and follow-up care.
Long-Term Effects
In some cases, especially after severe heat stroke, it can take weeks or even months to fully recover. Some people continue to experience:
Difficulty concentrating
Muscle pain or soreness
Mood changes or irritability
Increased heat sensitivity
Older adults and those with underlying health conditions may take longer to recover.
Tips to Prevent Heat Stroke
Heat stroke is serious, but it’s also preventable with certain precautions. Whether you’re working outdoors, exercising, or just spending time in the sun, here’s how to protect yourself:
Stay Hydrated
Dehydration makes it harder for your body to cool itself through sweating. Without enough fluids, your internal temperature can rise quickly in the heat, increasing your risk of heat stroke.
So be sure to:
Drink plenty of water throughout the day. Don’t wait until you’re thirsty.
Limit alcohol, caffeine, and sugary drinks, which can contribute to dehydration.
Dress for the Heat
Choose lightweight, light-colored, and breathable clothing.
Wear a wide-brimmed hat and sunglasses for extra protection.
Plan Around the Weather
Avoid outdoor activities during peak heat hours (typically 10 a.m. to 4 p.m.).
Take breaks in the shade or indoors if you’re spending time outside.
Use Fans and Air Conditioning When Possible
Air conditioning is the most effective way to cool down.
If you don’t have access to air conditioning, use fans, take cool showers, or visit public spaces like libraries or shopping centers during extreme heat.
Check in on Others
Keep an eye on children, older adults, and people with chronic illnesses, who are more vulnerable to heat-related illness.
Never leave anyone in a parked car, even for a few minutes. (This includes pets–even with the window cracked.)
See a Nice Clinician if You Have Health Concerns
If you have a chronic health condition or take medications that could affect your body’s ability to regulate its internal temperature or maintain proper hydration, checking in with a Nice Healthcare clinician is a smart step.
We’re here to help you stay ahead of the heat with personalized guidance that fits your lifestyle and health needs.
Whether you want to talk about prevention or just get peace of mind before the next heat wave hits, you can easily schedule an appointment right through the app–often on the same day.
Together, we’ll create a plan that keeps you cool, safe, and feeling your best all summer long.
If you’re not sure whether you have access to Nice Healthcare, check with your benefits manager.
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