Dehydration in the Wilderness

Star of lifeIt can be a serious thing depending on the severity, no doubt about it. We’ve all experienced a case of dehydration to one degree or another. However, in a survival setting where there is no easy, quick access to a water fountain, a refrigerator full of Gatorade, or a hospital to transport to, things can go downhill very, very quickly if dehydration is left unchecked.

Let’s begin with what dehydration IS. Clinically, it is the loss of water from body tissues, that can cause aggravated shock. It occurs when your fluid losses are greater than your fluid intake. When left untreated, dehydration can lead to shock and eventually, death. While anyone in a survival situation is at risk for dehydration given the right conditions, children are even more at risk due to their smaller fluid reserves, while the elderly are at an elevated risk due to less efficient body systems.

There are 3 types of dehydration:

  • Isotonic: Usually caused by severe/long term diarrhea and/or vomiting, systemic infection or intestinal obstruction.
  • Hypernatremic: Usually caused by excessive or misuse of diuretics, high sodium intake without increase in water intake (adversely, loss of water without loss of sodium), and severe diarrhea.
  • Hyponatremic: Usually caused by use of diuretics, heavy persperation, excessive loss of sodium/renal disorder, excessive water consumption.

Dehydration can lead to heat cramps, heat exhaustion, and eventually heat stroke. So it’s paramount to pack enough water for your excursion based upon your body’s needs (I carry a 3L hydration bladder from Source, $36 HERE). If you’re an experienced hiker/backpacker/outdoorsman, you have a general idea of what that need is and I’m not going to preach.

3 Liter hydration bladder by Source. ©2015

If you are a “newb” (which we ALL were at one point, so don’t be bothered by that), you may want to consider the old adage “8 glasses a day” or “8 by 8 (pm)” as a baseline. This means eight, 8oz glasses each day by 8pm. This converts to approximately 1.9 liters per day, depending on your body’s needs, and activity level. If you’re really new at this, make sure you have access to water back at camp, or along the trail, be it other campsites, streams, creeks, or other sources, and that you’re packing a reliable method of water filtration and/or purification. This is life or death stuff, so don’t shrug this off.

There are several ways to distinguish between cases of mild, moderate and severe dehydration. So let’s go over those.

Signs/symptoms of MILD (2%) dehydration:

  • Normal pulse
  • Normal or slowed level of activity
  • Decreased urine output
  • Normal skin tone/temp/appearance
  • Increased thirst
  • Decreased saliva (if you can build a mouthful of spit, that’s good)
  • Normal eyes/pupils
  • Normal level of consciousness
  • Headaches
  • Normal blood pressure
  • Normal/slightly sunken anterior fontanelle (“soft spot” on top of babies head)

By the time you notice most of these symptoms, you are already approximately 2% dehydrated, and about 1 liter of fluids down. Stop for a few minutes, find shade, drink water and rest.

Signs/symptoms of MODERATE (5-6%) dehydration:

  • Increased pulse
  • Slowed level of activity
  • Decreased urine output
  • Cool, mottled skin with poor turgor (elasticity)
  • Dry mucous membranes
  • Watery/teary eyes
  • Altered LOC (level of conciousness)
  • Headaches and/or dizziness
  • Normal blood pressure
  • Sunken anterior fontanelle (“soft spot” on baby’s head)

When you experience or witness the above symptoms, you are generally experiencing 5-6% dehydration levels, you are about 2 liters down on fluids and you need to stop. Don’t try and tough it out another 1/2 mile or 15 minutes, no, stop. In a wilderness setting, you are not near a hospital, your cell phones may not work, and life-flight is a ways out. If after a rest, shade and water/electrolytes, you don’t see a marked improvement on yourself or your buddy, it may be time for extraction.

Signs/symptoms of SEVERE (10%) dehydration:

  • Increased pulse (tachycardia); 160+ is shock
  • Weak to unresponsive level of activity
  • NO urine output
  • Cool, clammy skin with poor turor; delayed capillary refill time
  • Dry mucous membranes
  • Sunken eye
  • Altered LOC (level of consciousness); Lethargic
  • Normal to low blood pressure when shock sets in.
  • VERY sunken anterior fontanelles in children

You probably won’t experience any of these symptoms, because you will likely be unconscious, or close to it. So, if you are helping anyone who is, know they are likely at  roughly 10% dehydration and know that 15% is generally considered a fatal level of dehydration. Hopefully SAR (search and rescue) is on the way, or you have extracted your buddy and are en route to a hospital you were smart enough to chart & plot a course for ahead of time in your planning, for an emergency like this.

Now, these are clinical presentations of dehydration. It’s important to remember that not everyone has the same threshold for dehydration, nor will everyone present with these EXACT symptoms or even all of them. This is where experience and formal training come in (we go more in depth in our courses). But at least now, you have a basic understanding, and an idea of what to look for.

Combating dehydration can be simple if you know what you are doing (experience/training), and make sound decisions while you pay close attention to what your body is telling you. Generally speaking, once you start to suspect you may be dehydrated, you already are. So drink often as you adventure, do not wait until you are thirsty. The sensation of thirst is an early indicator of dehydration.

I use this brand frequently with great results FOR ME.
I use this brand frequently with great results FOR ME.

Electrolyte tabs are also a great way to stay hydrated and keep proper levels of sodium/potassium exchange happening within your body (a discussion for another day, entirely). There are tons of these tabs available on the market, they are not expensive, but they have the potential to save your butt. Any endurance athlete will tell you this, and I’ve personally used them in cases of moderate to moderately high dehydration when I’ve pushed myself a little too hard. Foolish, but it happens.

Don’t let your dehydration turn into heat cramps, heat exhaustion or heat stroke. Be proactive and attack it early by staying hydrated, keeping your activities responsibly near your skill levels, and know when to say when.

Ne te quaesiveris extra.



Mosby’s Paramedic Textbook, 4th ed. ©2012 by Mosby Inc.

Emergency, 10th ed. ©2011 by Jones & Bartlett

The Mayo Clinic, ©2015 by Mayo Clinic

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