The Prevention of Dehydration from Heat

With summer, starting it is important that we start to protect ourselves from heat related illnesses.  Dehydration is the most important factor leading to heat illnesses.  Water is a critical element in the body, and you must have adequate hydration for the body to function properly. The human body contains up to 75% water.
Dehydration occurs when the body loose water faster than it take it in.  The human body loses water for many reasons.

  • You lose moisture every time you take a breath
  • Sweating from exercise, you can sweat 2 quarts of water per hour.
  • Urination or bowel movements
  • Diarrhea
  • Vomiting

To protect yourself against dehydration in a hot environment, if hiking you should drink 1 gallon of water for every 20 miles you hike at night and 2 gallons per 20 miles during the day.  Colder liquids are more easily absorbed by the stomach.  Liquid containing carbohydrates will be absorbed by your system 30% faster than plain water.  Water diluted with ¼ to ½ Gatorade is ideal.  Higher concentrations of carbohydrates can cause stomach cramps.  Salt lost through sweating can be replaced by adding ¼ teaspoon of salt to a quart of water.  Don’t drink liquids that contain alcohol or large amounts of sugar.

Dehydration is classified as mild, moderate, or severe based on how much of the body’s fluid is lost or not replenished.   Severe, dehydration is a life-threatening emergency and medical help is needed.  If there is any doubt as to the severity of dehydration contact medical personnel, dial 911.


  • Dry or sticky mouth
  • Low or no urine output; urine appears dark yellow
  • Not producing tears
  • Eyes appear sunken
  • Lethargic or comatose (severe dehydration)

In addition to above symptoms, you may also have vomiting, diarrhea, or the feeling that you “can’t hold anything in your stomach”.

A physical examination can also show signs of:

  • Low blood pressure
  • Blood pressure that drops when you go from lying down to standing
  • Rapid heart rate
  • Poor skin turgor — the skin may lack its normal elasticity and sag back into position slowly when pinched up into a fold; normally, skin springs right back into position
  • Shock


Self treatment of dehydration should not be attempted except in an extreme emergency when medical professionals are not available.  Attempt to replace fluid  by oral re-hydration. Frequent small amounts of following clear fluids should be given by mouth.

  • Water,
  • Clear broths,
  • Jell-O
  • Other replacement fluids that may contain electrolytes (Pedialyte, Gatorade, Powerade, etc.)

Urine output is the best way for you to monitor the effects of re-hydration therapy.  As treatment progresses urine output increases and becomes clearer, less concentrated.

If the person becomes confused or lethargic; if there is persistent, uncontrolled fever, vomiting, or diarrhea; or if there are any other specific concerns, then medical care is required as soon as possible, dial 911.

Remember prevention is the best treatment for dehydration.

Heat Exhaustion and Heat Stroke are related to dehydration, but treated slightly differently.  I will talk about them in another post in a few days.



5 thoughts on “The Prevention of Dehydration from Heat”

  1. A veteran who is preparing

    Easiest solution to prevent and treat dehydration is to drink water. DO NOT drink caffeinated or very sugary drinks (like sodas) when it is extremely hot outside. Those will only dehydrate you worse. Gatorade is good (the military actually gives it out now to fight dehydration in hot climates). But water is still the best. DO NOT TAKE SALT TABLETS!!! The military learned the hard way that those literally eat the lining of your stomach. As long as you are not on a low sodium diet you should already be getting enough salt intake. Your body needs the salt to store water and use it efficiently.

    In our group we made it mandatory that everyone has to have the capability of carrying at least 2 quarts of water on them at all times. How they carry it is up to each member (whether it is by camelbak, canteen, or whatever). This is primarily for after TSHTF. Though I can be seen carrying my old 2-Quart Canteen when it gets over 90 each day. Old habits die hard.

  2. I agree that dehydration is a major problem that can be hard to solve. Dehydration has played a big part in my life as a runner. Because of this, I have founded Hydrate which is developing a wristband dehydration monitor. If you are interested in watching our progress check my website at:

    I also welcome all feedback in order to improve the product during development.

  3. This Navy Med newsletter for families has good information on prevention of sports and heat related injuries and proper hydration.


    1. Centers for Disease Control and Prevention. “Extreme heat: What is the public health problem?” 2004. (23 Mar. 2005).
    2. Stewart, C. (2002). Hyperthermia. In G. Bosker (Ed.), The Emergency Medicine Reports textbook of adult and pediatric emergency medicine (2nd ed.). Atlanta: American Health Consultants.
    3. Centers for Disease Control and Prevention. “Frequently asked questions about extreme heat.” 2004. (23 Mar. 2005).
    4. Wexler, R. K. (2002). Evaluation and treatment of heat-related illness. Am Fam Physician, 65(11), 2307.
    5. Carroll, P. (2002). The heat is on: Protecting your patients from nature’s silent killer. Home Healthc Nurse, 20(6), 377.
    6. Centers for Disease Control and Prevention. “Heat stress in the elderly.” 2004. (23 Mar. 2005).
    7. Virtual Naval Hospital. “Heat illness: A handbook for medical officers.” 1991. (23 Mar. 2005).
    8. Centers for Disease Control and Prevention. “Extreme heat: A guide to promote your personal health and safety.” 2004. (23 Mar. 2005).
    9. Tierney, Jr., L. M., McPhee, S. J., & Papadakis, M. A. (Eds). (2005). Current medical diagnosis and treatment (44th ed.). New York: Lange Medical Books/McGraw-Hill.
    10. Lugo-Amador, N. M., Rothenhaus, T., & Moyer, P. (2004). Heat-related illness. Emerg Med Clin North Am, 22(2), 315.

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