I know the theory behind effects of high altitudes on the human body is not entirely understood and because of cross-influence it is a difficult topic. It's not an exact science.

Having said that I will give an example case which happened to myself this year. I try to give all relevant information. And I am asking myself for quite a while (and therefore I am asking you now) what exactly occurred in my body in high altitude and how I could react better the next time.

My background is:

  • quite a few alpine tours under 4000m (13.000')
  • good fitness level but no fitness enthusiast (I am able to do tours with 10 hour walking and/or 2000m elevation gain without big problems in a proper speed)
  • mild lung problems (no 100% capacity, maybe 80-90%)

So we did a trip to South-America, started doing proper acclimatization tours where we always slept around 3000m (10.000') and climbed 4 mountains with increasing height between 4200m (13.800') and 5100m (16.700'). On that tours I had no problems at all and seemed to be very fit. We also had days to rest.

Then we tried to climb a mountain of 5900m (19.300') height. We were supposed to sleep from 5pm to 10pm which I wasn't really able to. I slept maybe 15 minutes which of course is not the best preparation for a long day. Still I was motivated, ate and drunk as much as possible before we start. We were driving by car until 4800m (15.700') I think. There we start climbing. From 5000m (16.400') on I got problems with the stomach. I felt bad and this got worse. As a consequence I wasn't able to eat and I even stopped drinking properly. Later on I was starting to feel weaker and weaker. I had no lung problems or problems breathing but I felt so extremely exhausted. I had no headache at all. Finally at 5500m (18.000') I made the decision to turn around. Even descending I had to stop and even sit down each few minutes because of the exhaustion. I never felt like this before.

I know it's normal to fatigue when you are not sleeping/eating/drinking enough. But the body has reserves. Because I had no headache I asked myself over and over again if I got AMS (wiki) and how serious my situation is and when I have to stop ascending. This is the main question here, how to decide and react properly in such a borderline situation.

There was a lot written about AMS and I knew the symptoms before my trip. This question covers the general ideas of diagnosing severe altitude illness. I doubt my question is a duplicate, it is just a very special case (a case example) which shows how difficult correct judging about the necessity to turn around is.

Like the linked Lake Louise Score states, it is always headache plus symptom X and maybe others. Because of the missing headache I was really unsure of my situation and how far to proceed. The mountain guides climbing with me are not able to assume the responsibility.

While descending under 5000m (16.400') I started feeling stronger. That's the main reason I assume afterwards that I got altitude sickness. But I (and also the mountain guides) was not able to judge correctly on the way up.

How would you judge? How would you react? What to do better next time preparing a high altitude climb?

  • Can you add more time indications (how many days in acclimatization, times on the day it happened).
    – imsodin
    Oct 19, 2015 at 15:15
  • @imsodin One week acclimatization. Started climbing at 12am, bad feeling in stomach started maybe at 1am. Still, I never had to puke which was the reason I tried to keep ascending as long as possible. I started descending at 4:30am and needed over two long hours back to the car.
    – Wills
    Oct 19, 2015 at 15:31
  • It seems obvious that you had an altitude illness. The question is how severe it was, and whether it was AMS, HAPE, or HACE. Did you have ataxia? Did you have rales? Were you able to catch your breath when resting, and speak in complete sentences? What do you get if you score yourself on the Lake Louise questionnaire? Recent work shows that sleep disorder is not a symptom of AMS.
    – user2169
    Oct 19, 2015 at 21:40
  • @BenCrowell Afterwards it seems obvious for me too. But ascending it was not so obvious (even for the guides). It was clearly no HAPE/HACE. I hope/guess it's easier to diagnose those very severe problems. I had no more symptoms beside the bad stomach and the fatigue. On the Lake Louise Score I would rate 1-2 for gastrointestinal symptoms (I felt like I have to puke but I can't) and 2 for fatigue (maybe even 3 as a reason to turn around). Could you please state the reference to the sleep disorder not being part of AMS. Thx
    – Wills
    Oct 20, 2015 at 6:03
  • Could you please state the reference to the sleep disorder not being part of AMS See this answer outdoors.stackexchange.com/a/9653/2169 . If your Lake Louise score was about 3-4, then you probably had mild to moderate AMS.
    – user2169
    Oct 20, 2015 at 14:23

3 Answers 3


My guess - you were not suffering AMS symptom, but you were in potentially big trouble. Normally AMS symptoms take time - up to 24 or even 48 hours to develop. When I was climbing Alpamayo (6000m), a guy got carried off after he came up from sea level and attempted the peak in a day. His aim was bag the peak (6000m) and get down to 3000 within 24hours and he would be 'safe' from AMS. Unfortunately for him he only made it down to 5000m that night. We never found out if he lived....

Sleeping at 3000 meters had acclimatised you to 3000 meters. You were 2500 meters above the highest level you had been sleeping at before you turned around. You were well acclimatised for the altitudes the previous trips got you to, BUT you had you climbed to those altitudes slowly? (indicated by "days of rest") .

However, on this trip you drove to 4800m and climbed above 5000m immediately - no indications of time taken, my guess is a couple of hours after leaving 3000m you were at 5000m - not enough time for your body to develop normal symptoms of AMS. Without AMS symptoms to slow you down, and feeling bullet proof from you earlier trips, you would have climbed at or above your O2 uptake maximums, you body responded to this sudden lack of available oxygen and increase exertion as a need for "fight or flight" for survival - it shut down you digestive system. After that, it was all down hill (pun intended).

Or you just got a normal stomach complaint from dodgy food or water.....

Edit: In response to the last line: What to do better next time preparing a high altitude climb?

I believe the main problem you had was sleeping at 3000 meters for a week then attempting 5900meters - The normal guidelines are around sleeping height gain of 300meters per day above 3000 meters, rest day after 1000meters, and climb high/sleep low typically refers to 'more than 300 meters' for the day climb, not the 3000 meters you attempted.

So next time plan to sleep higher and take more time. A week to get to 5900 is pushing it. Do overnight trips and stay at progressively higher altitudes.

  • Normally AMS symptoms take time - up to 24 or even 48 hours to develop. The OP describes being in the mountains at elevation for quite a long time, clearly many days.
    – user2169
    Oct 20, 2015 at 2:56
  • And you reach 2K :)
    – WedaPashi
    Oct 20, 2015 at 4:18
  • @Ben - My point is he was acclimatised to sleeping at 3000meters, then drove 4800m and started climbing. With no symptoms at 3000m, it could easily take 24 hours to develop them.
    – user5330
    Oct 20, 2015 at 4:36
  • 2
    .... after ascending quickly, lack of symptoms during a fast ascent is not a reliable way to diagnose the absence of AMS.
    – user5330
    Oct 20, 2015 at 4:44
  • When I try it the next time I will for sure take more time and I will try to sleep higher. Still the guides do this as their default strategy for those mountains highly accessible by car. This was not an expedition style where you increase sleep level by 300m per night. By the way we climbed slowly to acclimatize. And we did rest days. Because I tried to judge the situation I was in I was thinking about bad food as a reason for the stomach too... that's the point, it's easy in theory but it was not on the mountain.
    – Wills
    Oct 20, 2015 at 6:08

I guess one of the central concerns with AMS is that you can never know when it hits you. You can prepare, acclimatize and try to avoid all the stupid mistakes - but even under perfect conditions, and even if you have a successful history of climbing at altitude it can hit you any time.

From what you described I don't see any obvious mistakes. It sound like you prepared diligently and did your high altitude ascends slowly and carefully. It's unlucky, you still got symptoms which forced you to turn around.

On whether it actually was AMS or not: nobody can say for sure. As others mentioned, it could be AMS, or just some stomach bug, a common cold or similar. But I'd argue that it is not entirely relevant, as the symptoms can well be very dangerous either way, so it's better to err on the side of caution.

I guess the point to take away here is:

  • With the symptoms you described you should turn around - no matter what the cause is.
  • Depending on how easy the descend is you probably should have turned around sooner: always keep in mind where you are and what kind of exit strategies you can fall back on. While this doesn't have to be the case, I'd wager that in a situation where you would have been unable to walk off the mountain a rescue operation might have taken a long time to put together.

As a speculation, you may have a ceiling of about 16,500 feet. This speculation is reinforced by your starting to feel stronger as you passed 16,500 on the way down. Was this the first time you climbed above 16,500?

My husband had an office mate -- very tough, fit guy -- who puked regularly at 13,000 feet, and felt awful. Finally he accepted his ceiling.

You had AMS; you were very wise to go down when you did. (Better had you gone down earlier.) Whether you have a ceiling or whether you will be able to exceed the apparent ceiling of 16,500, no one can say, at this point -- unless you have a past history of climbing successfully above 16.5 that you did not include in your Q.

If you choose to try again (in your position, I would not push it again) don't get overtired beforehand (a day off can't hurt), sleep well the night before, warn your companions, be hyper-vigilant and be prepared to turn around when your body tells you to. If the symptoms of this trip recur, don't push it; get down. Get down before you feel "extremely exhausted". You could pass the point of collapse quickly if you continue. if you collapse, you are putting other people at risk. Don't wait until your brain does not work before making a decision to go down.

It is telling that you felt exhausted going down and that you "never felt like this before". If you ever feel like that again, go down! It's OK to feel exhausted moving up, but you should feel OK when you stop and rest, and you should feel much better as soon as you are on a downslope -- unless you have AMS.

The absence of a headache, considering your other symptoms, means nothing. Different people react differently. A headache is not obligatory to have AMS. The more I think about this, the more I think you had a close call.

  • 1
    Thx for the good answer. Do you have lecture to read about "ceilings"? Never heard of that before. On that trip I climbed for the first time over 4000m, later over 5000m and the top was 5500m then. Of course I am watching out more carefully next time, because I made this important experience. Still (besides the stomach) I was "just" exhausted, therefore my questioning of the whole situation.
    – Wills
    Oct 20, 2015 at 5:51
  • @Wills I don't have a ref for ceilings to hand, but I will look it up later today.
    – ab2
    Oct 20, 2015 at 11:25
  • 1
    @Wills -- I cannot find a reference for a Ceiling, although I did not Google exhaustively. My speculation was based on three pieces of anecdotal evidence, one of which I mentioned, plus a vague memory of reading something about personal ceilings. I think mattnz's recomendations in the last two paragraphs of his Answer make a lot of sense.
    – ab2
    Oct 21, 2015 at 17:14

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