The Importance of Hydration at Altitude - Dr Ross Anderson

A successful ascent on Baruntse | Simon Yates
A successful ascent on Baruntse | Simon Yates

Hydration at altitude is even more important than at sea level. Spotting early signs of dehydration is absolutely critical to a mountaineer's success. Dr Ross Anderson takes us through the signs of dehydration and what to do if you are dehydrated on the mountain.

What is dehydration? 

Water usually enters the body as liquids and a small amount in food. Dissolved in water are salt and electrolytes that also play a vital role in the smooth running of body systems. Water and salt/electrolytes can leave the body as urine, sweat and sometimes vomit or diarrhoea.

Dehydration is a serious condition where the body is short of the required amount of water to function normally. Mild dehydration is common in those who are active in the mountains and is a result of more water leaving the body than is taken on board.  On average, 1.5L to 3 litres of water is required per day in an adult at sea level. However, more water is required in situations where you come down with diarrhoea/vomiting, in warm/hot conditions, when exercising and when acclimatising to high altitudes.

Summit of Lhakpa Ri |  <i>Soren Kruse Ledet</i>

The symptoms of dehydration are not always easy to recognise.

Thirst is not as reliable as you may think.  The first symptoms tend to be tiredness, weakness, a moderate to severe headache, irritability and dizziness.  These are also symptoms that we associate with other common conditions in the mountains, namely Acute Mountain Sickness and to a lesser extent, low levels of sugar in the blood. We therefore have to be mindful of the need to consider other conditions at the same time.

The key to recognising dehydration is when you pass small amounts of dark urine - hence it is important you keep an eye on the urine's colour. This is because the kidneys are trying to preserve water.

More severe dehydration can be detected through sunken eyes, a dry tongue and a weak, rapid pulse and breathing rate.

Treatment of dehydration:

The aim is to slow down body water losses and begin replacing water.  When dehydration is due to exercise at altitude, this usually requires a combination of drinking more, resting and cooling down.  Non-diet drinks and snacks containing sugar can help in cases where low blood sugar levels are also present.

If you are dehydrated due to exercise and are able to eat, then small but regular sips of plain water is all that is required to rehydrate. If little food is being eaten for whatever reason and dehydration more severe, oral rehydration solutions should be considered.

Oral rehydration solutions:

These replace vital salts and electrolytes that the body depends on to function normally. It also makes it easier for your body to retain water when drinking the solution, which can be a problem if you only drink plain water and are not eating. You can buy sachets of rehydration salts or even make it up yourself.

Beautiful shot from the trek up Kyajo Ri |  <i>Tim Macartney-Snape</i>


In severe cases of dehydration, a medical opinion is required and some cases end up being put on a drip e.g. those unable to keep any fluids down due to persistent vomiting. Hopefully after reading this article you will be better able to spot the early signs of dehydration and step in before it becomes more severe.


For more information, see Chapter 18 of Pocket First Aid and Wilderness Medicine 3rd edition by Drs Jim Duff and Ross Anderson (our past and present medical experts). You can buy a copy from TrekSafe or Cicerone Press.


climbing, health tips, hiking, hydration, mountains

Comment (0)

Your comment will be visible after the administrator's approval.

b i u quote

Save Comment
Join Newsletter
<img src='/portals/World%20Expeditions/Icons/brands/small/ADS.jpg' class='brandPopoverIcon' alt="Adventures South"> <div class='brandPopoverBrandName'>Adventure South</div>
Adventure South NZ is unrivalled in their geographic coverage, originality and overall quality of adventures holidays in New Zealand. Choose from walking, cycling, winter or multi-activity holidays, on either the North or South Island.
<img src='/portals/World%20Expeditions/Icons/brands/small/AWH.jpg' class='brandPopoverIcon' alt="Australian Walking Holidays"> <div class='brandPopoverBrandName'>Australian Walking Holidays</div>
Australian Walking Holidays specialises in small group guided walking adventures. Since 1982 we have been guiding small groups of travellers on Australia's finest walks across our tropical, coastal or red centre landscapes.
<img src='/portals/World%20Expeditions/Icons/brands/small/GCT.jpg' class='brandPopoverIcon' alt="Great Canadian Trails"> <div class='brandPopoverBrandName'>Great Canadian Trails</div>
Great Canadian Trails specialises in active holidays in Canada. With both guided and supported self-guided options available, our unique itineraries draw upon some of Canada's most inspiring parks, trails and landscapes from coast to coast.
<img src='/portals/World%20Expeditions/Icons/brands/small/HUM.jpg' class='brandPopoverIcon' alt="Humac Challenge"> <div class='brandPopoverBrandName'>Huma Charity Challenge</div>
Huma enables those with adventurous spirits to challenge themselves and make a difference for a cause close to their heart. Travel, fundraise and meet life-long friends on one of Huma's meaningful and unique challenges around the world.
<img src='/portals/World%20Expeditions/Icons/brands/small/WB.jpg?v2' class='brandPopoverIcon' alt="Walkers’ Britain"> <div class='brandPopoverBrandName'>Walkers' Britain</div>
Walkers' Britain (formerly Sherpa Expeditions) have specialised in walking and cycling trips in the United Kingdom and Europe since 1973. Explore iconic trails and destinations on a self guided or small group active holiday with Walkers' Britain.
<img src='/portals/World%20Expeditions/Icons/brands/small/WB.jpg?v2' class='brandPopoverIcon' alt="Walkers’ Britain"> <div class='brandPopoverBrandName'>Walkers' Britain</div>
Walkers' Britain (formerly Sherpa Expeditions) have specialised in walking and cycling trips in the United Kingdom and Europe since 1973. Explore iconic trails and destinations on a self guided or small group active holiday with Walkers' Britain.
<img src='/portals/World%20Expeditions/Icons/brands/small/TAS.jpg' class='brandPopoverIcon' alt="Tasmania Expeditions"> <div class='brandPopoverBrandName'>Tasmanian Expeditions</div>
Tasmanian Expeditions is the most experienced operator of treks and adventure travel holidays in Tasmania. We own and operate the most comprehensive range of adventure holidays available across Tasmania's varied landscapes.
<img src='/portals/World%20Expeditions/Icons/brands/small/UTX-new.jpg' class='brandPopoverIcon' alt="Utracks"> <div class='brandPopoverBrandName'>UTracks</div>
UTracks are the active European holiday specialists. Whether you prefer cycling or walking, 2-star or 4-star, small groups or self guided, land, river or sea – UTracks can help you to explore Europe exactly the way you want.
<img src='/portals/World%20Expeditions/Icons/brands/small/WYA.jpg' class='brandPopoverIcon' alt="World Expeditions Schools"> <div class='brandPopoverBrandName'>World Expeditions Schools</div>
World Expeditions Schools is our specialist division dedicated to organising tailor made overseas school group adventures. Specialists in Service Learning projects, choose from more destinations than any other school group provider.
<img src='/portals/World%20Expeditions/Icons/brands/small/YOM.jpg' class='brandPopoverIcon' alt="Yomads"> <div class='brandPopoverBrandName'>Yomads</div>
Yomads offers adventures for the 20s and 30s on six continents. Designed as a way to bring young and likeminded travellers together, Yomads caters to those interested in lightly structured and active trips that allow freedom to roam and explore.
<img src='/portals/World%20Expeditions/Icons/brands/small/ACT.jpg' class='brandPopoverIcon' alt="Australian Cycle Tours"> <div class='brandPopoverBrandName'>Australian Cycle Tours</div>
Australian Cycle Tours specialises in high quality self guided and guided cycling experiences in a selection of the most beautiful regions in Australia.
<img src='/portals/World%20Expeditions/Icons/brands/small/WEX.jpg' class='brandPopoverIcon' alt="World Expeditions"> <div class='brandPopoverBrandName'>World Expeditions</div>
The pioneers of original, worldwide adventure travel holidays since 1975
<img src='/portals/World%20Expeditions/Icons/brands/small/TJX.jpg' class='brandPopoverIcon' alt="Trail Journeys"> <div class='brandPopoverBrandName'>Trail Journeys</div>
Self-guided cycling experts on New Zealand's Otago Rail Trail and more
<img src='/portals/World%20Expeditions/Icons/brands/small/BMAC.jpg' class='brandPopoverIcon' alt="Blue Mountains Adventure Company"> <div class='brandPopoverBrandName'>Blue Mountains Adventure Company</div>
The original Blue Mountains canyoning, hiking, climbing and abseiling experts
<img src='/portals/World%20Expeditions/Icons/brands/small/GWNZ.jpg' class='brandPopoverIcon' alt="Great Walks of New Zealand"> <div class='brandPopoverBrandName'>Great Walks of New Zealand</div>
Explore New Zealand's most spectacular wilderness regions with the self-guided hiking experts
<img src='/portals/World%20Expeditions/Icons/brands/small/NAA.jpg' class='brandPopoverIcon' alt="North America Active"> <div class='brandPopoverBrandName'>North America Active</div>
USA Canada hiking & cycling tour specialists, choose from self-guided or guided trips