You’re outside in the sun, having a great time.  You remembered your sunscreen and your water, and you’re getting your exercise in.  Gradually, you feel fatigued and you start sweating more or stop sweating altogether.  Is it heat stroke or heat exhaustion?

Heat stroke can occur in healthy, young individuals, children, and the elderly.  There are two main forms of heat stroke:  exertional and non-exertional.  Exertional heat stroke is the result of exertion, such as yard work, outside labor, exercise, and sometimes just moving around in very hot “heat wave” temperatures.  This is the type of heat stroke associated with most young people.  Non-exertional heat stroke is most often related to the elderly, the lightly mobile, and sedentary and can strike without having any physical activity—which can look confusing if an elderly person suddenly becomes incoherent but you haven’t seen them move around enough to make you even consider heat stroke as a possibility.

Heat stroke is life-threatening and is defined as a temperature equal to or greater than (or 40°C). I’m going to outline some emergency procedures and warning signs, but it’s important to remember to get those that are suffering from a possible heat stroke into the hands of trained medical professionals.  Heat stroke can be deadly and in serious cases can result in organ failure or coma.

Exertional heat stroke is usually developed in able-bodied individuals engaging in rigorous physical activity, and again, non-exertional heat stroke is usually developed in the elderlyIt’s interesting to note that non-exertional heat stroke can often affect elderly who have been inside during the hot temperatures.               

The elderly are much more at risk because of the diseases that may affect them; medications like diuretics, beta-blockers, and anticholinergics; and the age-related impairment that reduces the body’s ability to re-route blood to dilated blood vessels in the skin for cooling, and the insufficient intravascular volume to increase sweating.  The types of mediations above may decrease the sweating needed to dissipate heat.

Children are also at risk for heat stroke because they have a lower thirst response when dehydrated, sweat less, and have a larger ratio of surface area relative to their mass which means they absorb more heat from the environment.

Don’t forget that dogs and cats are also at risk for heat stroke.  If you’re suffering, they’re suffering.  Always make shade and water available to dogs and cats and avoid walking them at the hottest part of the day, especially on asphalt roads.  Seek veterinary care if animals refuse to drink water, pant excessively, drool excessively, are extremely lethargic, fast heart rate, and not urinating.  Remember that panting in cats is never normal.

Heat stroke, a.k.a. hyperthermia, is a body temperature greater than 104°F and a “disturbance of consciousness”.

The difference between heat stroke and heat exhaustion:

Heat stroke strikes quickly and acutely and symptoms include dry skin (no perspiration), dizziness, a rapid, strong pulse, nausea, and confusion.

                Heat exhaustion usually takes place after several days of exposure to hot temperatures and is usually a result of dehydration.  Symptoms include heavy sweating, a fast, weak pulse, and rapid breathing.  Heat exhaustion can progress into heat stroke if not treated.

                If you experience or someone near you experiences these, seek emergency medical help and try to actively cool them as you wait.  There is a right way and a wrong way to cool them.

What to do if you or someone around you has these symptoms:

  • Call for medical professional help/transport them to the medical help
  • Remove non-essential clothing
  • Apply ice packs or crushed ice packs all over the body. Although we may have been told to apply them to the neck, armpits, and groin, this is not enough to cool someone down.  Apply these ice packs to entire body.
  • For non-exertional heat stroke, spray the body down with cool water and fans or continuous airflow
  • Because the cooling cannot be done indefinitely and has to be stopped once a drop in body temperature occurs, remember to seek medical professional help for these situations

Studies have indicated that by 2050, heat stroke is expected to rise 2.5 times the baseline of 2,000 deaths per year.

Heat stroke and exhaustion can be preventable, but situations can always occur outside our control.  Remember to stay hydrated, try to avoid being outside during the hottest parts of the day, wear light-colored clothing and a hat, and check-in regularly with how you and your people are feeling.


  1. Hifumi, Toru et al. “Heat stroke.” Journal of intensive care vol. 6 30. 22 May. 2018, doi:10.1186/s40560-018-0298-4


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