Dehydration, heat exhaustion and heat stroke

Summer temperatures regularly exceeding 30°C pose an increased risk of dehydration, heat exhaustion and heat stroke. How to recognize and avoid these health complications? 

Heat exhaustion and dehydration

Dehydration and heat exhaustion often go hand in hand, especially during the summer. You can think of dehydration as a depletion or imbalance of fluids and electrolytes in the body. If combined with prolonged exposure to the sunlight and heat, dehydration can lead to heat exhaustion. Staying hydrated greatly reduces the risk of heat exhaustion or other heat-related illnesses.

What factors can contribute to dehydration?

Alcohol and caffeine

Many people do not realize that beverages containing alcohol or caffeine increase the likelihood of dehydration. Both caffeine and alcohol serve as diuretics, increasing the amount of water expelled from the body as urine. If you do not compensate for the loss of fluids by drinking more water, alcohol and caffeine consumption can eventually lead to dehydration. Moreover, drinking alcohol before or during exposure to sunlight and heat impairs the body’s ability to regulate its temperature, thus increasing the likelihood of heat exhaustion.

Sport

Do not forget to stay properly hydrated while doing sports in the summer. If possible, exercise in the morning or in the evening and limit your exposure to direct sunlight. In extreme conditions of high environmental heat stress, prepare your body by heat acclimatization – gradual physiological adaptation to exercise. Remember that exertional heat-related illnesses can have dire consequences on your health. If you experience nausea, vomiting, dizziness, muscle cramps, or other symptoms that are mentioned below, stop the exercise immediately, stay out of the direct sunlight, rehydrate yourself and try to cool down. If the symptoms persevere, call the emergency. Extra precautions should be taken by older people, people with chronic diseases or pregnant women.

Who is at risk of dehydration and heat exhaustion?

Young children (especially infants), older people, pregnant women and people with chronic diseases are at a greater risk of dehydration and heat exhaustion. Be especially careful if you take any prescription medications. Although you might not be aware of it, many medications act as diuretics, increasing the risk of dehydration. A common example are blood pressure medications and any medications that list diarrhea or vomiting as a potential side effect. Watch out for your pets too, and make sure they stay hydrated and do not spend long time on a direct sunlight.

How can you tell if someone is dehydrated?

  • Symptoms of mild dehydration
    • thirst, restlessness, slightly sunken eyes
  • Symptoms of severe dehydration
    • lethargy, unconsciousness, poor drinking / inability to drink, lack of urine output, low / undetectable blood pressure

Severe dehydration is considered a medical emergency and requires immediate professional attention.

Heat exhaustion

How can you prevent heat exhaustion?
  • Check the heat index before outdoor exercise (heat index combines air temperature and relative humidity)
  • Dress appropriately; wear light, loose clothing so sweat can evaporate
  • Use sunscreen to prevent sunburn
  • Avoid beverages containing alcohol or caffeine
  • Acclimatize before beginning any intense exercise
  • Hydrate well, especially before and during exercise
  • Exercise in the morning or in the evening
What are the symptoms of heat exhaustion?
  • Muscle cramping
  • Rapid, weak pulse
  • Weakness
  • Nausea or vomiting
  • Excessive sweating
  • Dizziness or fainting
  • Dark-coloured urine
  • Headaches
How to treat heat exhaustion?
  • Move to a cool place
  • Lie down and raise your feet slightly
  • Rehydrate
  • Cool your skin (spray or sponge with cool water)

Heat stroke

If the symptoms of heat exhaustion remain untreated, they may eventually lead to a heat stroke. Heat stroke is a more serious condition than heat exhaustion and it is considered a medical emergency. There are two types of heat stroke – exertional heat stroke and non-exertional heat stroke. Exertional heat stroke occurs in people whose bodies can no longer adapt to rising temperatures while exercising or working (usually affects people who spend time outdoors). Its onset is generally quick, within few hours. Non-exertional heat stroke usually occurs in older adults, infants or people with chronic illnesses who cannot adapt to increasingly hot temperatures.

You might experience heat stroke if you:
  • have symptoms of heat exhaustion which do not soothe after 30 minutes
  • feel hot and dry
  • are not sweating even though you’re too hot
  • your temperature that has risen to 40°C or above
  • have a rapid or shortness of breath
  • are confused
  • have a seizure
  • lose consciousness
  • are unresponsive
If not treated immediately, heat stroke can damage multiple organs and systems including:
  • Brain and nervous system
  • Circulatory system
  • Lungs
  • Liver
  • Kidneys
  • Digestive tract
  • Muscles

If you witness someone experiencing symptoms of heat stroke, call the ambulance immediately.

 

Heat Exhaustion & Dehydration Symptoms | NextCare Urgent Care. (n.d.). Retrieved from https://nextcare.com/health-resources/heat-exhaustion-dehydration/

M.A., P. C. (2017, December 20). Dehydration: Symptoms, causes, and treatments. Retrieved from https://www.medicalnewstoday.com/articles/153363.php

Diuretics: Types, Use, Side Effects, and More. (n.d.). Retrieved from https://www.healthline.com/health/diuretics

Heat emergencies: MedlinePlus Medical Encyclopedia. (n.d.). Retrieved from https://medlineplus.gov/ency/article/000056.htm

Nichols, A. W. (2014). Heat-related illness in sports and exercise [Abstract]. Current Reviews in Musculoskeletal Medicine,7(4), 355-365.

Quinn, E., & Fogoros, R. N. (n.d.). How to Prevent and Treat Heat Exhaustion During Exercise. Retrieved from https://www.verywellfit.com/athletes-and-heat-exhaustion-3120206

Heat exhaustion and heatstroke. (n.d.). Retrieved from https://www.nhs.uk/conditions/heat-exhaustion-heatstroke/

Fletcher, J. (n.d.). Heat stroke vs. heat exhaustion: Differences and treatment. Retrieved from https://www.medicalnewstoday.com/articles/321972.php

 

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