What’s the Difference Between Heat Exhaustion and Heat Stroke?

Heat stroke is the more severe form of heat illness that can lead to unconsciousness or death. Here are the symptoms to look for that set it apart.

Summer means outdoor fun, ice cream, long days followed by warm nights, and the chance to stock up on some must-have vitamin D. However, it also means taking extra care to look after yourself and your family, including the family pet (be aware of these warning signs of heat stroke in your dog) in the higher temperatures. When the body gets too hot, heat exhaustion can occur—and if that’s not treated it can lead to something much more serious: heat stroke.

What's-the-Difference-Between-Heat-Exhaustion-and-Heat-StrokeMaridav/Shutterstock

According to family physician and assistant professor at Rowan University School of Osteopathic Medicine Jennifer Caudle, DO, the symptoms of heat exhaustion vary but can include muscle cramps, heavy sweating, fatigue or weakness, fast heart rate, nausea or vomiting, and pale or cool skin. “Some of the signs of heat stroke can overlap with heat exhaustion,” says Caudle. “But the difference with heat stroke is that you also have a fever of 105 (or higher) and there is dysfunction of the central nervous system, such as fainting/unconsciousness or seizures.”

“When we discuss heat stroke and heat exhaustion, we are talking about two different problems that exist on a spectrum of heat illness, with heat stroke being a more severe form of heat illness,” explains Neha Raukar, MD, associate professor in Emergency Medicine at Brown University. “Heat exhaustion is on the less severe end of the spectrum of heat illness. It occurs in high temperature environments, and intervention is required, even if that intervention is just taking a break, so the disease does not progress to heat stroke, which can be fatal.” In addition to a high core body temperature, typical symptoms of heat stroke include fainting/dizziness, vomiting, confusion or disorientation, and unusual behavior, such as aggression.

What's-the-Difference-Between-Heat-Exhaustion-and-Heat-StrokeWerayuth Tes/Shutterstock

While heat exhaustion doesn’t normally require medical attention, it’s important to treat the symptoms immediately. This involves moving to a cooler location, sipping water, and applying cool, wet clothes to as much of the body as possible. When it comes to heat stroke, however, Raukar advises calling 911 immediately for appropriate medical attention. “Current treatment methods include cooling blankets, cold-water immersion, application of ice packs, and evaporative cooling with fans and misting,” she says.

Since heat exhaustion and heat stroke exist on the same spectrum of illness, Raukar’s recommendations for avoiding them are the same: Avoid strenuous activity in hot temperatures (such as exercising, mowing the lawn, or playing sports), wear loose, light clothing, seek out shade or air conditioning if you think you are getting overheated, and sip water or cool fluids to help keep the body cool.

And don’t forget sunscreen! Check out our guide to the best sunscreens for every kind of activity.

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