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The Difference Between Heat Exhaustion and Heat Stroke (and How to Treat Them)

Ms. Carroll is an avid outdoors person and environmental activist. She was a Wilderness First Responder for 10+ years.


Heat can be a silent killer. Often times, the condition of either heat exhaustion or heat stroke occurs very suddenly. Heat Exhaustion isn’t necessarily a killer itself, but it can certainly lead to heat stroke, which is. Therefore, it is important to understand the difference between the two conditions and act on them in the early stages of each condition.

Heat exhaustion is basically dehydration. The signs and symptoms are overt and the victim will likely complain loud enough to be heard. They will feel weak, nauseated, thirsty, and frequently complain of a headache. It usually occurs in settings where the patient has been sweating profusely, but that is not to assume the setting will be unusually hot.

Heat exhaustion can be confusing where vital signs are concerned. The blood pressure and temperature can increase or remain stable. The pulse and respiration will increase, but the skin may be warm or it may be cold and clammy. A notable symptom will be urine output so ask someone complaining of the symptoms of dehydration when they last took a leak. A decrease in urine is a sure sign as the body is seeking to retain it’s fluid levels.

Symptoms of Heat Exhaustion vs. Heat Stroke

Heat ExhaustionHeat Stroke






Possible Headache

Altered Mental Status such as confusion or aggravation

Increased pulse & respiration

Increased pulse & respiration

Usually stable blood pressure & core temperature

Increased core temperature

Decrease in urine output

What to Do?

Have someone suffering from heat exhaustion cease all exertion. Find them shade or create shade, and hydrate them with anything available (opt for something cool or room temperature rather than hot coffee!). If there has been heavy sweating, increase their salt intake. Remember that drinks like Gatorade and Powerade are strong on electrolytes, but short on sodium. (I usually carry along a couple of salt tablets on a trip where there will be heavy physical exertion in extreme temperatures.)

Heat stroke is a different animal. The core body temperature will approach 105 degrees. This will cause an altered mental status noticeable in a manner of ways. Heat stroke patients may appear delusional or irritated. Others may appear confused. Vital signs will appear much the same as someone suffering from heat exhaustion, so in the absence of a thermometer, you must rely on a person’s mental status to tell you what’s going on. Heat stroke patients need to be cooled immediately, preferably with a mist fan. There is no time to spare. They should be hydrated and evacuated, both as soon as possible.

Once the body’s core temperature increases to the point where mental status is altered, there is a risk for an increase in intra cranial pressure (ICP). This is also life threatening. You may be able to manage heat stroke until you can reach definitive medical care, but once ICP ensues, the outlook is much more critical and medical intervention will definitely be required. An ICP patient will become combative and will very likely hurl!

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If you anticipate a trip in extreme temperatures, hydrate well before the trip and carry adequate hydration for the duration of the trip. GORP (good old fashioned raisins and peanuts) is a sure-fix for simple dehydration, but salt supplementation may be necessary in extreme cases. Every circumstance must be judged individually, and when practical and possible, seek medical advice first. Otherwise, maintain a cool head and it is likely that your victim will obtain a cool head with you.


The following information is based on my certification and training as a Wilderness First Responder. Every circumstance is different. When at all practical and possible, seek the assistance of a medical professional.

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DesertMan on March 09, 2011:

All good advice and it was an easy read. Thanks.

TheSablirab on March 18, 2010:

Thanks for the Hub; am starting to read about the symptoms of both on the site, so thanks for another great Hub.

successfulblogger from Los Angeles,Ca on December 04, 2009:

I have been out in the middle of the desert and it is horrible.

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