Version July 2025
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What is heat stroke? —
This condition can happen when a person's body gets too hot. Most often, it happens when people exercise in very hot and humid weather without drinking enough fluids. But heat stroke can also happen in people who are not exercising. It is especially likely to affect older people, people who have health problems, and young children and babies. These people need to be extra careful in hot conditions.
Heat stroke is a medical emergency that needs to be treated quickly. If not, it can lead to death.
When people get too hot, they can also get "heat cramps" and "heat exhaustion." These other, less serious forms of heat illness.
What are the symptoms of heat stroke? —
People with heat stroke have:
●A body temperature of 104°F (40°C) or higher
●Brain symptoms – These can include:
•Confusion or trouble thinking clearly
•Seeing or hearing things that aren't real (called "hallucinating")
•Trouble walking
•Seizures
•Passing out
Heat stroke can also cause:
●Fast breathing or fast heartbeat
●Skin redness and warmth – The skin might feel moist or dry.
●Vomiting or diarrhea
●Muscle cramps or weakness
●Headaches
Should I see a doctor or nurse? —
Yes. If you or someone you are with has heat stroke, get medical help right away. Call for an ambulance (in the US and Canada, call 9-1-1).
Is there a test for heat stroke? —
Yes. The doctor will do an exam and check your temperature. They will probably need to take your temperature rectally to get the most exact result. To do this, a doctor or nurse will insert a thermometer into your anus.
The doctor will probably also do other tests to find out if the heat stroke hurt other organs in your body. These tests can include:
●Blood tests
●Urine tests
●Chest X-ray
●Electrocardiogram ("ECG") – This measures the electrical activity in your heart (figure 1).
How is heat stroke treated? —
The main treatment involves cooling the body down as soon as possible. Doctors can do this in different ways. It might involve using a fan to blow air on wet skin, pouring cold water over you, or putting you in an ice bath. If possible, this might be done before taking you to the hospital.
In the hospital, your doctor will also treat any other problems the heat stroke has caused.
How can I prevent getting heatstroke? —
When it is hot or humid out, you can do the following things:
●Try not to be too active, and take breaks when you exercise.
●Drink enough fluids, such as water or sports drinks, so you do not feel thirsty. But don't force yourself to drink very large amounts in a short time, and don't drink so much that you feel uncomfortable. This can be harmful.
●Exercise early in the day, before it gets too hot out.
●Wear loose, lightweight clothes. Don't wear too many layers.
●Avoid being in a hot car.
Watch for symptoms of heat cramps or heat exhaustion. Heat cramps cause painful muscle cramps. Heat exhaustion can cause headaches, dizziness, nausea, or vomiting. It can also make you thirsty or tired.
If you have symptoms of heat cramps or heat exhaustion, cool your body down right away to avoid getting heat stroke.
To cool your body down, you can:
●Spray yourself with cool water, and then sit in front of a fan.
●Move into the shade, or go into an air-conditioned building or car.
●Take a cool shower or bath.
●Drink water or a sports drink. Avoid drinks with alcohol or caffeine.
●Take off any extra clothing.
●Put multiple cold packs or cool cloths on your body. Replace them as soon as they are no longer cold. It might help cool you down faster to put cold packs on the front of your neck, armpits, and groin area.
Patient education: Hypovolemia in adults (The Basics)
Patient education: Dehydration in children (The Basics)
