What to expect when you’re ascending: Acute Mountain Sickness

As the final countdown to departure looms closer, I have focused my energy on understanding what I can expect in terms of the possible (likely) responses to high altitude, namely acute mountain sickness (AMS).

AMS refers to an umbrella of symptoms experienced by unacclimatized individuals with initial exposure to high altitude.  The cluster of AMS symptoms are headache, gastrointestinal symptoms, fatigue, dizziness/light-headedness, and overall poor sleep quality.

For unacclimatized individuals (such as yours truly), exposure to low oxygen (hypoxic) environments triggers a physiological response intended to increase the amount of oxygen breathed in by the lungs.  These adjustments to breathing in response to low oxygen induces a number of physiological changes that are thought to lead to the characteristic symptoms of ‘high altitude sickness’ and more serious health complications found in individuals who ascends too quickly or ignore/mismanage initial symptoms.

Generally speaking, how fast you ascend, the altitude reached, the altitude that you sleep at, and individual physiological differences determine the likelihood of developing AMS.  At altitudes above 3000 m, the incidence of AMS is around 40 – 50%; however, there currently aren’t any strong predictors of  who will get sick.  Fitness, age, gender, previous high altitude experience, and a host of other individual factors appear to have no conclusive bearing on whether an individual will develop these symptoms in high altitude.

As such, the ascent profile of our trek has been designed to provide the best opportunity for acclimatization and hopefully reducing AMS symptoms.  This includes slow ascent (< 600 m per day) and rest days at 3340 m, 3860 m, and 4240 m.  Further, we’ll be taking daily doses of a drug called acetazolamide (Diamox), which has been shown to speed up the acclimatization process and reduce incidence of AMS.

How my body will respond to high altitude is one of the the biggest unknowns as I prepare for this trip.  I have been to altitudes of 2500 – 2700 m on multiple occasions and felt fine; however, given that our trek begins at 2840 m, I guess I’ll have to wait and see how my body deals with a low oxygen environment.

If you want to learn more about AMS and more serious (life-threatening) high altitude illnesses, such as high altitude cerebral and pulmonary edema, check out BasecampMD.com and Altitude.org.

4 thoughts on “What to expect when you’re ascending: Acute Mountain Sickness

  1. St Francis of Assisi School grade 4/5 class. Congratulations Jeremy.
    We are wondering how you will carry your equipment up the mountain.
    We also wanted to know how you got the other people from other countries to come with you?


    1. Hey Ms. Longo and your grade 4/5 class, thanks for your interest! Most of the heavy lifting will be done by animals. Our heavier bags and equipment will be carried by yaks on trek. We will carry necessities like water, snacks, first aid supplies, and warm clothing in smaller packs while we hike. Our hike will go from mountain village to mountain village, so the yaks will eventually meet up with us at the end of each day.
      In terms of the people on our team, the people from other countries are friends of the trek organizers. Since we need research subjects (human guinea pigs), these people volunteered to participate in the research, but really it’s an excuse to go to Mt. Everest!

      Thanks for your questions, keep them coming!


      1. We are really excited for you to leaving soon. We hope to see pictures of the Yaks and how you carry your equipment. Can you also post a picture of the equipment and what you carry in the bag. We also checked out the airport you were landing in, was it exciting to land there?


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