Here's What You Need to Know About Heat Exhaustion as 'Heat Dome' Sizzles

As extreme summertime heat becomes more common and lasts longer, the risk of heat-related deaths and illnesses increases. This week, a massive "heat dome" is cooking the Midwest and Northeast.  While a variety of serious health impacts, including heart attack, can result from excessive temperatures, heat exhaustion and heat stroke are among the most common. Here are some of the most important things to understand about heat stroke (and its precursor, heat exhaustion) as well the primary symptoms to look out for.  

Those most at risk when temperatures rise include the very young — under 4 years old — and the elderly, said Dr. William Hauptman, a gastroenterology specialist in Pennsylvania. "The central nervous system is involved in regulating body temperature, and when you're young or older it may not work as well," Hauptman explained. Those with chronic illnesses such as diabetes, or who take medications for health conditions such as high blood pressure, are also vulnerable. 

Heat stroke begins with heat exhaustion, making it critical to first understand the signs of heat exhaustion. "The way to think about it is there's this continuum," Hauptman said. "Heat stroke is what we would see at the end of that continuum if people aren't tuned into recognizing the early signs. So the really important discussion is what are the signs of heat exhaustion, so that it doesn't progress to heat stroke, which can be life threatening."

Among the red flags for heat exhaustion are excessive sweating and muscle cramps, as well as dizziness, fainting, fatigue, headache, nausea, and vomiting. The signs and symptoms may develop suddenly or over time, particularly with prolonged periods of exercise or work in hot weather.

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Don't be fooled into thinking it has to be 90-plus degrees for heat exhaustion or heat stroke to occur. "In the mid-80s, with very high humidity, in patients who are predisposed to heat exhaustion, you can begin to see the symptoms," Hauptman said. "You see it more frequently when temperatures are in the 90s, but people should realize you can see in the 80s as well." 

To stop heat exhaustion from progressing, Hauptman recommends four actions he refers to as "move, loosen, cool, and drink." The first step to take is to move out of the hot sun to someplace cool. "If you're outdoors, move into the shade," he said. "Even better, move into an air-conditioned environment."

The next step to alleviate heat exhaustion is to loosen your clothing. "If you're wearing tight clothing, it's going to increase the progression of symptoms," Hauptman said. So loosen your belt, roll up your pants, and unbutton your shirt to help alleviate the symptoms.

Jumping into a pool or a lake to cool down when signs of heat exhaustion are present is not necessarily a good idea. Yes, it will cool the body's temperature, but given that the other signs of heat exhaustion are fatigue and dizziness, swimming is not safe, Hauptman said. Instead, cool the skin by spraying it gently with water or immersing in a cold bath or shower. Cool sponges can also be used, or the person suffering from the symptoms can be wrapped in a cool sheet. 

Drink fluids to help counteract the symptoms of heat exhaustion — but don't run out to buy a soda or anything that might have caffeine, which could be dehydrating. It's important to stick to water or sports drinks. As a general rule, those who have to be outdoors during high temperatures should drink 8 ounces of water every 15 to 20 minutes, Hauptman said. 

Heat exhaustion symptoms can worsen over the course of several days. "If someone is shut in an apartment, doesn't have ready access to fluids, and is unable to take the necessary measures, the symptoms can evolve," Hauptman said. "And if you don't take the appropriate measures, it can cause heat stroke — and that's when your body's cooling mechanism totally fails." Heat stroke is the most serious type of heat injury, and is a medical emergency.

While heat exhaustion is characterized by excessive sweating, one of the primary indicators that someone has shifted to heat stroke is a sudden lack of sweat, Hauptman said. "Instead of sweating you have dry, hot, flushed skin," he said. A body temperature of between 102 and 104 degrees is another indicator of heat stroke, as is red, hot, and dry skin. Heat stroke victims may also have a change in mental status, including confusion, decreased coordination, or unconsciousness.

Heat stroke is life-threatening. If it occurs, call 911 — though if it's possible to rush someone with heat stroke to a hospital more quickly on your own, that's an option, Hauptman said. What you should not do, however, is now treat it with a drink. "If someone has progressed to heat stroke, they may not be able to drink," Hauptman said. "Giving them a drink could do more harm than good. Do all of the other things you would do when someone has heat exhaustion: Move them to a cool environment, loosen their clothing, and cool their skin, but do not give someone who may have heat stroke a drink."

While heat exhaustion may progress over the course of days, heat stroke can have a severe impact in a matter of minutes, Hauptman said. "It can evolve over 15 minutes," he said. "If you don't take care of the initial symptoms of heat exhaustion and the body temperature rises to really dangerous temperatures — and we've seen body temperatures of 106 degrees — then it's life-threatening because it affects the brain, kidneys, and heart." 

Often, during heat waves, those who cannot afford air conditioning go out and buy fans to cool themselves instead, which is a very bad idea, Hauptman said. "Using a fan does more harm than good," he explained. "It's almost like a convection oven. It can worsen the situation. It just moves the hot air around. If people don't have access to air conditioning, they should get to a mall, a library, or a shelter. We have people dying all the time during heat waves who have a fan on." 

Hundreds of people die each year from heat exhaustion and heat stroke, Hauptman said. Whenever there's a heat wave, headlines are filled with stories of affected people — but they don't always mention what the cause of death was. "The elderly, the sick, people without resources who don't have air conditioning, you always read about their deaths during heat waves, and that's from heat exhaustion and heat stroke."