Dehydration: Understanding and Prevention

13 min read

Dehydration is a serious concern in outdoor adventure, such as hiking and backpacking. It can occur in the winter or summer, on a backcountry expedition or a day hike. Excessive heat, vigorous exercise and a lack of clean water can all lead to dehydration. This article will help you expand your basic understanding of the problem. For Scout Leaders, summer camp counselors and others who lead in the outdoors, it is a guide to preventing the problem to begin with.

In October of 2018, a 26-year-old man died of dehydration while hiking at one of Australia’s most popular tourist spots, Nature’s Window. According to news sources, Kismatul Muzahid collapsed while completing a hike in Kalbarri National Park. A doctor, who was on the same walk, performed CPR on Muzahid but he could not be revived. Police said that Muzahid did not have the proper clothing or enough water for the five-mile trek. 1

In another incident, a 16-year-old Arizona teen died after falling ill on a popular hiking route in Israel. She was traveling with a tourist group of teenagers, according to The Times Of Israel. The teen was evacuated by helicopter to a nearby medical center, but she was pronounced dead upon arrival. Officials said that the group did not have enough water with them to stay hydrated in the intense heat. 2

An Illinois man died on a hike in the Saguaro National Park near Tucson, Arizona. Bradley Hughes was found dead on a trail in the park. Officials say that his water container was empty and that dehydration may have been a factor in his death. Temperatures in the area reached the mid-90s on that day. 3

While the above incidents are tragic, many people take on strenuous hikes in extreme conditions quite safely. The important thing is to be prepared. As an outdoor leader, you are the key to helping prevent dehydration among group members. We’ve developed this guide to help you learn the basics of dehydration and how to treat it.


What is Dehydration?

Human Organs and Hydration

Water is a critical element for human survival. It makes up approximately two-thirds of the body. Most of the body's water is found in the blood vessels, cells, and the spaces between the cells. A water deficit of as little as 2% of body weight can impair your capacity for exercise. For the body to function correctly, adequate hydration is a must. When the body loses more water than it takes in, dehydration occurs. 4

Causes of Dehydration

Dehydration is caused by losing more fluid than you take in. Many conditions can cause rapid fluid loss and lead to dehydration.

Excessive Sweating

You can become dehydrated if you sweat too much. Although exercising in hot weather can cause excessive sweating, it doesn’t need to be hot for a person to sweat too much. Having a fever and certain health conditions can cause increased sweating, as well. 5

Diabetes And Other Diseases

People with diabetes are at an increased risk of becoming dehydrated. The reason for this is because they have high levels of glucose in the bloodstream. The kidneys try to get rid of glucose by creating more urine. The body then becomes dehydrated because the person is urinating more often. For leaders, it is important to remember this when the time comes to review the medical history of participants.

Significant Injuries To The Skin

One of the skin's primary functions is to protect against fluid loss. When severe injuries to the surface, such as severe cuts or burns occur, it can cause dehydration. Water loss occurs through the damaged skin. Severe sunburn from overexposure to the sun can occur during outdoor adventure. 6

Increased Urination

An increased output of urine can lead to dehydration. Certain medical conditions, diuretic medications, and pregnancy can all cause increased urination. 7

In altitude diuresis the body's effort to acclimatize to high altitude increases blood acidity. To eliminate bicarbonates from the blood urine output increases. Water loss can be as much as 15% greater as compared with sea level. In hypothermia a reduction in antidiuretic hormone (ADH) is a cause of cold diuresis. Causes like these are easily overlooked and lead to increased urination when hiking, backpacking or climbing.

Lack Of Safe Drinking Water

Having access to clean drinking water is imperative for survival. When you run out of water and don't have access to safe drinking water, dehydration can result. Sarah Beadle, an emergency room physician from Fort Worth, Texas, died while hiking in the Grand Canyon after she got lost and ran out of water. 8

Alcohol Intake

Alcohol is a diuretic. So, drinking too much alcohol can result in dehydration. The headache that people commonly experience with a hangover is a sign of dehydration. Those who have recently consumed alcohol should avoid outdoor adventure especially in extreme weather conditions.

Heat Exposure

Extended exposure to extreme heat and sun can cause dehydration. Hot weather can lead to an increase in your body's core temperature. When the body's temperature rises, it works hard to cool itself down. This process usually results in an increased sweat output, which can lead to the loss of fluid. The loss of fluid can lead to an imbalance in electrolytes and dehydration. Exercising at high temperature presents an even greater risk of dehydration. 9 In fact, heat exposure was a factor in all the deaths described above.

Don’t Assume

Victims of cold related illness, both frostbite and hypothermia, almost always present at hospital as dehydrated. Don’t assume dehydration will only be a risk in hot weather.

Diarrhea & Vomiting

Diarrhea and vomiting are two of the most common causes of dehydration. A significant amount of fluid can be lost with diarrhea and vomiting. Hikers who become lost out in the backcountry may experience diarrhea and vomiting when they try to drink from contaminated water sources, such as streams. 10

Symptoms of Dehydration

Symptoms of Dehydration

Symptoms of Dehydration

It is essential for wilderness group leaders to recognize the signs of dehydration and know how to manage the condition. Dehydration can range from mild to severe. Here are the symptoms: 11


  • Increased thirst

  • Dry mouth

  • Muscle cramps

  • A headache

  • Decreased urine output

  • Dry, cool skin

  • Dark yellow urine


  • Feeling dizzy or faint

  • Confusion

  • Irritability

  • Rapid breathing

  • Rapid heartbeat

  • Heart palpitations

  • Extremely dry skin

  • Sunken eyes

  • Sleepiness

  • Weakness

What Happens When Someone Becomes Dehydrated?

The body's initial response to dehydration is to increase water intake. Urine output will become less as the body tries to conserve fluid loss. As the level of dehydration increases, the body will try to maintain cardiac output by increasing the heart rate. Blood vessels constrict in the effort to maintain blood pressure and keep the blood flowing to vital internal organs. The body will route blood away from the skin to the internal organs. It sends blood to the brain, lungs, heart, intestines, and kidneys to compensate for the loss of fluid. The skin will feel cold and clammy as the blood is diverted from the surface to vital organs.

If dehydration is not corrected at this point, then the brain will lack the blood flow that it needs to function. The person will likely become confused or weak. The kidneys might fail as the person's blood pressure falls. Finally, organ failure, coma, and death will occur.

How To Treat Dehydration

The best way to treat dehydration depends on many factors including the person's age, the cause, and the severity. Here are some general guidelines.

Mild to Moderate

When treating mild or moderate dehydration, the first step is to get the victim out of the direct sunlight and heat. Remove excess clothing to reduce sweating. Encourage the person to slowly replace lost fluids and lost electrolytes by drinking frequent, small amounts of clear liquids. If the dehydration is moderate, an oral rehydration solution may be needed to help balance the body’s electrolytes. 12


In severe cases of dehydration, intravenous fluids (IV) may be required. Correcting water imbalances may not be enough. Severe dehydration is a medical emergency. If a person is exhibiting the following symptoms, you should initiate a plan for early evacuation. 13

  • Weakness

  • Lightheadedness

  • Vomiting

  • Changes in mental status

  • Confusion

  • Lethargy

  • Coma

Prevention of Dehydration

Prevention is the best medicine when it comes to dehydration. Here are some tips for preventing dehydration. Outdoor leaders must set an example and educate the group to adhere to the discipline that prevents dehydration. Make sure all participants know it is essential they follow these guidelines to keep from becoming dehydrated.

Drink Before Feeling Thirsty

The best way to prevent dehydration is to drink water early and follow a regular schedule of consumption. Pre-hydrate a couple of hours before the hike or outdoor activity. Aim to drink at least 16 ounces of water an hour before engaging in physical activity or hitting the trail. 14 Doing this will help ensure you feel your best throughout the event.

How Much to Drink?

The answer to this question depends on many factors, including the level of exertion, climate, and altitude. A good rule of thumb is to drink one quart of clear liquid every two hours. If the hike is particularly strenuous or the weather is hot, one quart per hour may be needed.

Carry Ample Food And Water

Make sure you carry more than enough food and water. You need both to prevent dehydration. A hydration reservoir is a good option for extra water. Be prepared with a water treatment method, such as chlorine dioxide tablets. These are lightweight and inexpensive. Plus, these tablets are effective against the three main types of bugs, including giardia.

Foods that contribute to hydration

Balance Food and Water Intake

When engaging in hiking or strenuous activity, it is essential to balance fluid consumption with food intake. Aside from staving off dehydration and keeping electrolytes balanced, the proper balance of food and water will help you feel your best. Salty snacks, such as energy bars or nuts, are great for a day hike or intense activity as they help replace sodium loss.

Take Frequent Water Breaks

Make sure you include frequent but short water breaks on your outing. Aim for a ten-minute break at least once per hour. If you have trouble remembering to break, set a timer on your cell phone or watch.

Short breaks are beneficial, and they should not slow you down very much. Not only will short breaks provide an opportunity to rehydrate, but they help you remove waste products that build up while exercising, such as lactic acid.

Don’t Drink Too Much

Drinking too much water is possible. Overhydration can lead to a life-threatening electrolyte imbalance called hyponatremia. In 2014, a 17-year-old Georgia high school football player died after drinking too much water and Gatorade during football practice. The teen suffered massive brain swelling from over-hydration and later died. 15

Due to the risk of overhydration, do not force fluids. Stop drinking when you feel quenched. Your body can't absorb more than a cup of water every fifteen minutes. Have an electrolyte replacement solution in reserve to replenish lost minerals.

Avoid Alcohol Before Your Outing

Avoid consuming alcohol before strenuous activities like hiking, skiing, and canoeing. It can contribute significantly to dehydration. If you are planning an outing in the morning, opt for water instead of beer the night before.

Know When To Go

If you are planning a hike or outdoor activity in a hot climate, choose the right time to go. Avoid beginning your trek between 10 AM and 4 PM if the event involves strenuous exercise. Start the day early, even before dawn if possible and finish your outing in the early afternoon. This allows you to acclimatize during the cooler part of the day. And, it will help you avoid hiking or exercising in direct sunlight during the hottest part of the day. Be willing to modify your plan for the day if needed.

Sun temperatures in certain areas, such as deserts, can reach as much as 20° Fahrenheit hotter than posted temperatures. 16

Wear The Right Clothes

Dressing appropriately for the weather can help prevent dehydration and related conditions like sunstroke. When hiking in warm weather, choose light colors that reflect the sun's rays rather than absorb them. White, tan and khaki clothing will help keep you cooler. Clothing should be loose-fitting and breathable. Wear a cooling scarf or bandana. Protect your head and neck.

Since a sunburn can increase dehydration, make sure you wear plenty of sunscreen. Hats provide shade so bring along a wide-brimmed hat.

Be Prepared

Be prepared with the right supplies if dehydration strikes. Make sure you have the knowledge and supplies on hand to treat dehydration. Oral rehydration salts or tablets are a lifesaver. They are also very lightweight and easy to carry.

If someone in your group becomes dehydrated, don't panic. Stop, think, keep a cool head and follow the advice above. These problems take time to develop and they are only resolved over an extended timeline. There is no instant fix. So, demonstrate the leader-willpower to avoid hasty decisions that can create second victims.

If you have not already, consider taking a Wilderness First Aid class. It will reinforce and make clear the importance of everything we discussed above.

More Work for You - Homework!

We mentioned some products in the text of this article. It would be a good idea for you to have a better understanding of what they are. And more importantly, what they are not.

Many people come to Wilderness First Aid with a legacy of training - often hearsay - things they heard somewhere, sometime. To make the point more clearly - none of the stuff on the following list is a salt tablet. My advice is this: Give five or ten minutes to a quick google search and gain a more accurate idea of what these things are and what they are used for.

  • oral rehydration solution

  • chlorine dioxide tablets

  • electrolyte replacement solution

  • oral rehydration salts or tablets

Emily Mendez, M.S., Ed.S is a former psychotherapist who began her writing career developing psychology-related content. She has since discovered a passion for writing about health, fitness, travel and psychology.


1. Kalbarri National Park Hiker Death.

2. American Teen Dies After Becoming Dehydrated During Negev Hike.

3. Heat May Have Killed Hiker Found In Saguaro Nat'l Park.

4. What is Dehydration?

5. Causes of Dehydration.

6. Symptoms and Signs of Dehydration in Adults.

7. Symptoms of Dehydration.

8. Grand Canyon Hiker Dies After Water Runs Out.

9. Your Health in Hot Weather.

10. What Causes Dehydration?.

11. What is Dehydration? What Causes It?

12. How to Treat Dehydration.

13. Can I Treat Dehydration at Home?

14. Drink Enough Water to Stay Safe Outside.

15. Drinking Too Much Water Can Be Fatal To Athletes

16. Summer Hiking - Hike Smart.

Wilderness First Aid training in July