everest summit

What Happens to Your Body at the top of the highest mountain on earth?

Words: Steve Root
Photo above: Harry Kikstra / Getty Images

Going up can really get you down. Like, in a deadly way. We explain why.

When climbing to extremely high elevations — say, for example, 29,029 feet (over 8,000 metres) up Mt. Everest — it’s common knowledge to slowly acclimatise at increasingly higher elevations to try to mitigate the nasty side effects of hypoxia or oxygen deprivation. The process can take weeks, but even then, there’s a physical limit at about 25,000 feet, above which the human body can no longer acclimatise. It’s called the Death Zone and it definitely lives up to its name — while in that zone, the body is literally dying. 

In the old days of climbing, the common thinking was to sleep closer to the summit, rest up and make a final push to the top, but at that altitude, climbers were in essence sleeping themselves to death. Now, the modern approach is to sleep much lower and to make a final “mad dash” to the top and quickly back down and into a safer zone.

So what exactly happens to the human body up there? Take a look. It isn’t pretty:

everest summit

Denali Summit Ridge; 20,220 ft.

© Adam Clark


With the onset of hypoxia, pulse rate soars, blood thickens and clots, and the risk of stroke rises. Worsening conditions can lead to high altitude pulmonary edema (HAPE).  Here, the lungs accumulate fluid, and victims can quickly drown in their own fluids. Symptoms include a mildly elevated temperature and extreme shortness of breath even at rest (tachypnea). With a stethoscope, you can hear clicking and rattling in the lungs created by the gurgle of fluid. Descending while still under your own power is highly recommended, lest you die and put a damper on the entire expedition.


With hypoxia, the heart rate can zoom up to 140 beats per minute, called tachycardia, and with it, the increased risk of stroke or sudden cardiac arrest. Speed-freaks and cokeheads notwithstanding, most hearts generally do not enjoy this.


Eyes can experience nasty looking hemorrhaged blood vessels, resulting in red splotches. It looks bad, but given the choice, opt for that over snow blindness, which can occur without proper protection, and it’s just what it sounds like: A temporary loss of vision due to glare from snow and ice. What the name doesn’t convey is the sheer agony of it: With sunburned corneas, even the slightest light can feel like needles in the eyes, so better just kick back and sleep it off. Yeah, in the Death Zone.

summit denali

Denali; 19,700 ft.

© Adam Clark


In addition to nausea and vomiting, in the Death Zone, digestion becomes nearly impossible, so even if you do consume food with the decreased appetite that comes at high altitudes, the body can’t really do much with the fuel anyway.


HACE or “high altitude cerebral edema” is to the brain what HAPE is to the lungs: Swelling and serious business. As the body struggles for oxygen by increasing circulation, the brain can begin to swell. In addition to the easy stuff, like nausea and vomiting, HACE brings on a decreasing level of consciousness, difficulty thinking and reasoning and general “stupidity.” Sufferers have been known to have bizarre hallucinations, chat with imaginary companions and lose their will and judgement (doing things like ripping off protective clothing in sub-zero temps). 


The obvious problem for extremities, like fingers, toes and noses is frostbite, but you should be so lucky as to just lose a few of those. Of much greater concern with HACE is physical incoordination. And a 29,000-foot icy peak with sheer ice walls and bottomless crevices is no place to lose your ability to walk. Diamox, oxygen canisters and pressure bags can bring temporary relief, but the first and foremost treatment is to get the hell down.​

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02 2016 RedBulletin.com

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