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How to Know If You're Dangerously Overheated

As the U.S. is pummeled by heatwaves, it's important to know the signs of heat exhaustion.

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People walk downtown as the temperature reached around 115 degrees in early June in Calexico, California.
People walk downtown as the temperature reached around 115 degrees in early June in Calexico, California.
Photo: Sandy Huffaker (Getty Images)

We’re only two weeks into summer, and heatwaves are already scorching the United States. Memphis, Tennessee hit a daily record high temperature of 100 degrees Fahrenheit (38 °C) on June 17. Three days later Houston, Texas hit a daily record of 102 degrees (39 °C). Multiple regions of the country have seen dangerous daytime and nighttime temperatures, while other countries including Japan, France, Spain, and even Norway have struggled through record breaking heat.

Now that dangerous temperatures are reaching what used to be considered “temperate” regions, everyone should learn how to stay safe.

Symptoms of heat exhaustion to look out for 

Dr. Priscilla Agyemang, an assistant professor of Medicine at Columbia University Vagelos College of Physicians and Surgeons, and a primary care physician, says there are different levels of “heat injury.”


“Heat exhaustion is one of the earlier parts of that, and it basically is our body’s inability to adequately circulate blood due to excess heat or excess strenuous exercise,” she said. “Warning signs would be if someone would feel weak, they would feel dehydrated, maybe they would get a headache. Other symptoms would be abdominal symptoms like cramps or vomiting, even diarrhea… and some muscle pains as well.”

Some victims of heat exhaustion will break out in a heavy sweat as their body tries to cool down, but as the dehydration gets worse, they’ll stop producing sweat, Agyemang said. Related warning signs of impending heat exhaustion include a headache or the inability to urinate. And because both of those symptoms can be associated with other problems, some people ignore the signs, so it’s important to pay attention to your body.


What to do if you think you have heat exhaustion

Anyone who feels that they are struggling through an especially hot day or environment needs to find a cool or shaded area where they can rest, as soon as they can. Then make sure you drink water, along with anything that helps replenish electrolytes, like sports drinks and juice.


“[Drink] Gatorade or Pedialyte, something with electrolytes, kind of what you would do when you’re sick. Give yourself not just water, but other electrolytes that you lose in the sweat,” Agyemang said. “Sweat is salty… so you have to replenish salt and other things.”

Agyemang says that anyone who feels lethargic from the heat should try to rest for the rest of the day. Until the dehydration symptoms go away, don’t engage in any strenuous activities.


Symptoms of heat stroke, and when to seek medical intervention 

When heat exhaustion becomes worse, internal body temperature rises to around 103 degrees Fahrenheit. In addition to displaying the symptoms of heat exhaustion, heat stroke victims are often very hot to the touch, and their skin is dry because they can no longer sweat.


This is when neurological symptoms start to kick in. “If someone feels heat exhaustion symptoms and then begins to feel disoriented and confused, despite moving to a cooler area and drinking fluids… it may be time to go to the hospital,” Agyemang said. If a victim doesn’t get medical treatment, they could lose consciousness. These patients often have to be covered in cooling blankets and receive IV fluids. If treatment occurs in time, most patients admitted for heat exhaustion and heat stroke can make full recoveries.

Delaying treatment can lead to permanen damage. “Dehydration reduces the amount of blood that’s available… so we can’t circulate enough blood to the organs when we are severely dehydrated,” Agyemang said. “Our body is not made to work at certain temperatures.”


Take smart precautions on hot days

If you can’t avoid the heat or being outside during a hot summer day, avoid clothing that isn’t made out of a breathable fabric, like cotton or linen. Consider carrying extra water and a sports drink. If you’re not a Gatorade fan, buy Pedialyte or electrolyte packages that can be poured into water bottles. Don’t skip meals on a hot day, and if you can, opt for water-based fruits and vegetables.


Your best solution is to stay in the shade or somewhere that’s air conditioned and cool. The less exposure to heat the better.