If You Notice This on a Hot Day, Call 911 Immediately, Experts Warn

This surprising symptom could be your body's way of warning you about a deadly condition.

If you feel like you're more susceptible to hot weather these days and need to take extra special care on a summer day, it's not your mind playing tricks on you. For one thing, the earth keeps getting hotter (just take a look at the research provided by The National Oceanic and Atmospheric Administration (NOAA)!). Secondly, as we get older we become more vulnerable to the heat.

"As we age, our ability to adequately respond to summer heat can become a serious problem," reports the National Institutes of Health (NIH). "Older people are at a significantly increased risk of heat-related illnesses, known collectively as hyperthermia, during the summer months."

Read on to learn what surprising symptom could be a red flag that you're experiencing hyperthermia—and why you should seek help immediately if you notice it.

READ THIS NEXT: If You're Over 65, Never Do These 4 Things on a Hot Day, CDC Says.

Hyperthermia has three distinct stages.


The three main stages of hyperthermia are heat cramps, heat exhaustion, and heatstroke. While you may not associate muscle pain and spasms with dehydration and heat-related conditions, heat cramps are "painful, involuntary muscle spasms that usually occur during heavy exercise in hot environments," according to the Mayo Clinic. "The spasms may be more intense and more prolonged than are typical nighttime leg cramps," their experts write.

Heat exhaustion, the next main stage of hyperthermia, may manifest with heavy sweating, a weak pulse, nausea, and fatigue, among other symptoms. If heat exhaustion progresses to heatstroke, the condition can be fatal.

Some of the symptoms of heat exhaustion and heatstroke overlap: Other signs include headache, confusion, rapid heart rate, nausea or vomiting, and loss of consciousness, according to Beaumont Health.

Your body needs fluids in order to produce sweat.

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If you're overheated, you're drenched with sweat—right? Not necessarily. It's true that your body cools itself by producing sweat. "When your internal temperature rises, your sweat glands release water to the surface of your skin," explains Healthline. "As the sweat evaporates, it cools your skin and your blood beneath your skin."

But if you're dangerously hot, your body may not be able to regulate your temperature using its tried-and-true method of cooling off with sweat.

"When the body's temperature increases very quickly, it is unable to compensate using its usual cooling mechanisms such as sweating," warns Donna Schisler, RN, BSN, Clinical Manager at Advantis Medical. "Many times, this is brought on by spending too much time in the heat and becoming dehydrated."

That's because people frequently forget, or are unable, to stay adequately hydrated in severe heat—and fluids are needed in order to replace the water the body loses in the heat.

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Heatstroke is the final stage of hyperthermia.

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Approximately 700 people die of heat-related conditions each year in the U.S., according to the Centers of Disease Control and Prevention (CDC), with 90 percent of these deaths occurring between May and September.

"Heatstroke is deadly and can quickly result in injury and death without treatment," Schisler warns. "During heatstroke, the body loses the ability to regulate its temperature due to outside factors such as humidity or temperatures that are so high that sweating is inadequate."

Being mindful of the heat is the first step in preventing hyperthermia. Many people in a hot environment don't always remember to hydrate or take breaks to cool off. It's also important to know the signs of heat-related conditions—which may surprise you. You might associate being overheated with heavy perspiration. But not sweating can be your body's way of telling you that you're in serious danger.

Staying hydrated is one way to keep the healthy sweat flowing.


Making sure to drink fluids—as well as knowing which fluids to stay away from—is an essential component in preventing heat stroke and other stages of hyperthermia. "During physically strenuous activities, drink fluids such as sports drinks that contain electrolytes and salt to replace the minerals your body has sweat out," advises Schisler, adding that it's best to stay away from alcohol and sugary drinks.

Schisler also recommends checking the temperature before you go outside, especially in the summer, and using air conditioning when the heat is above 90 degrees. "A fan is not sufficient to avoid heatstroke," she warns. "If you need to go out during the afternoon when the sun is strongest, dress appropriately with flowy, light-colored clothing, wide brimmed hats, and bring an umbrella for shade. Wear sunscreen when in the sun, as the body cannot regulate temperature appropriately when sunburned."

Luisa Colón
Luisa Colón is a writer, editor, and consultant based in New York City. Her work has appeared in The New York Times, USA Today, Latina, and many more. Read more
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