How to Identify Heat Stroke and Heat Exhaustion

It’s been a sweltering hot summer, marked by record-setting temperature highs and undeniably long heat waves across the U.S. 

As tens of millions of residents across the West remain under excessive heat warnings, per the National Weather Service (NWS), concerns about heat-related illnesses have risen. 

Experts warn that the extreme heat can cause exhaustion or heat stroke, which can be deadly when treatment is delayed. “When a person is losing a lot of sweat from heat, not able to keep up with the body’s demand to maintain homeostasis, to maintain itself, [it can lead to] heat exhaustion…[or] the more serious kind of the heat exhaustion then can lead to heat stroke,” says Dr. Jerome Cohen, president of the Medical Society of the State of New York. 

Heat kills more people than hurricanes, tornadoes, or other natural disasters. Some 1,220 people in the U.S. die every year because of extreme heat, according to the Centers for Disease Control and Prevention (CDC). Nearly 30 people have died in the West this July due to the prolonged sweltering heat wave that also brought temperatures that reached the 120-degree mark on Sunday in Death Valley, Calif.

Here’s what to know about the signs of heat stroke and heat exhaustion. 

Signs and symptoms 

Heat-related illnesses occur when the temperature of the body rises so rapidly that it cannot cool itself down. Heat exhaustion usually happens before heat stroke, though Cohen says that heat stroke can also happen on its own. 

Heat exhaustion happens due to dehydration. “Sweat is the way the body tries to get the temperature down. But they’re sweating so much, it’s just not keeping up with demand,” says Cohen. Excessive sweating causes the body to lose water and electrolytes. The CDC says that the elderly, people with high blood pressure, and those who have to work in hot conditions are more likely to experience heat exhaustion. 

Read More: How to Cool Down When It’s Really Hot Outside

Symptoms of heat exhaustion include nausea, weakness, sweating more than usual, headaches, dizziness, and elevated body temperature. 

Heat stroke is the most serious heat-related illness, a CDC spokesperson told TIME.  Someone may be experiencing heat stroke if they feel confused, have slurred speech, lose consciousness, or experience a seizure. Their body temperature can reach as high as 106°F in up to 15 minutes, causing them to either profusely sweat or have hot, dry skin. A pounding pulse is also a severe symptom. 

“The difference between heat exhaustion and heat stroke [is that] with heat exhaustion, you see skin that’s kind of pale and cold and clammy, whereas with heat stroke, the skin is going to be hot and red,” says Cohen. 

Multiple instances of heat exhaustion can cause organ damage. Rhabdomyolysis, which causes the body to breakdown muscle tissue faster can also happen, Heat also causes the 

What to do if you are experiencing these symptoms

Some 1,220 people in the U.S. die every year because of the extreme heat, according to the Centers for Disease Control and Prevention. Cohen says that as soon as someone starts to feel muscle cramps, lightheadedness, or feels nauseous, they should go seek shade. Drinking water or sports drinks, which have electrolytes, are also helpful. 

People experiencing symptoms of any heat-related illness should immediately seek medical attention. In more extreme cases, people should call 911 or be taken to the emergency room. If you are near someone who is experiencing these symptoms, make sure to stay with them until help arrives, and try to move them to a cooler, more shaded area. 

“If a person is feeling like they’re going to lose consciousness, going to faint, that’s a much more serious symptom,” says Cohen. If someone faints, they cannot drink and will need to have fluids put into the body using intravenous lines.

To cool someone, try removing their outer clothing, placing cold wet cloths on the skin, soaking their clothing with cool water, or giving them a cold water or ice bath if possible, the CDC says.