Why Doctors Are Increasingly Warning That Heat Exhaustion Strikes Faster Than Most People Expect
Heat waves are arriving hotter, longer and more often, and heat exhaustion can hit faster than most people realize. Here’s how to spot the warning signs, who faces the highest risk and what to do in the critical minutes before help arrives.
What are the warning signs of heat exhaustion?
Heat exhaustion typically shows up as heavy sweating, muscle cramps, headache, nausea, weakness, dizziness and a faster heart rate, according to Dr. Brett Bentley, a sports-medicine specialist at the University of Alabama.
Bentley told the Tuscaloosa News that heat illness runs on a spectrum, starting with painful cramps in the calves, hamstrings or feet caused by dehydration and low electrolytes. Heat exhaustion follows as the body loses water and salt through heavy sweating. “Someone suffering heat exhaustion will appear weak, lethargic, and just want to sit down. There’s a lot of fatigue,” Bentley said. If early signs appear, stop activity and cool down right away before symptoms escalate.
How is heat exhaustion different from heat stroke?
Heat stroke is the life-threatening escalation of heat exhaustion, marked by a core body temperature of 104 degrees or higher and sudden changes in mental status.
While heat exhaustion causes fatigue, cramps and dizziness, heat stroke brings confusion, slurred speech and fainting. “With heat stroke the mental status changes. They can’t answer basic questions, how they are, what they’re doing, the day of the week, all this kind of thing,” Bentley said. Exertional heat stroke can strike young, fit athletes when exercise pushes internal temperatures to 100 to 104 degrees, and further increases can trigger cascading organ failure, brain damage and death. Classic heat stroke often hits vulnerable people inside hot, poorly ventilated homes without air conditioning.
Who is most vulnerable to heat exhaustion?
Extreme heat can affect anyone, but young children, older adults, people who are overweight and those with chronic conditions such as diabetes, hypertension or cardiovascular disease face the highest risk.
Alcohol and certain medications also raise susceptibility, including diuretics, tricyclic antidepressants, antipsychotics and some cold and allergy remedies. Women may be marginally more vulnerable to heat-related death than men, according to Dr. Cat Pinho-Gomes, an academic public health consultant at the UCL Institute for Global Health, who spoke with the BBC. A 2025 research study found women produce less sweat and start sweating at higher temperatures, which makes it harder for the body to shed excess heat. Dr. Nighat Arif, an NHS GP specializing in women’s health, told the BBC that hormonal fluctuations during menstruation, perimenopause, menopause, pregnancy and breastfeeding can put the brain’s temperature regulation “out of kilter.”
What should you do immediately if heat stroke sets in?
Call 911 right away if someone shows signs of heat stroke, then move them to shade, remove excess clothing and cool them with water, ice packs or damp cloths until responders arrive.
For heat exhaustion, stop activity, get out of the sun and rehydrate before symptoms progress. Bentley told the Tuscaloosa News that heat illness is “largely preventable” with smarter timing. “Less strenuous outdoor activity is certainly a good idea, or try to go early in the day, or later, after dawn or dusk,” he said. Symptoms vary by person, and some medications or health conditions can mask overheating, so watch closely for headache, heavy sweating, dizziness and confusion in anyone spending long stretches outside.
Why are heat exhaustion cases expected to keep rising?
Climate scientists link the growing frequency and intensity of heat waves directly to human-caused climate change, which is expected to push heat-related illness and death higher in the coming years.
Heat-related illnesses already claim more U.S. lives annually than hurricanes, lightning, earthquakes, tornadoes and floods combined, with more than 9,000 heat-related deaths recorded between 1979 and 2014. Fatalities peak during heat waves and hotter-than-average years. Jennifer Francis, a climate scientist at the Woodwell Climate Research Center, told the Associated Press that “heat waves like this are so directly connected to the climate crisis and climate change and it’s because of how we’ve been burning fossil fuels and cutting down forests for so long and increasing the concentration of heat-trapping gasses in the atmosphere.” Francis added, “These kinds of heat waves and droughts and associated fires are all increasing just as we would expect them to in a warming world.”
This article was created by content specialists using various tools, including AI.
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