The Essentials of Altitude Sickness

Posted: Monday November 7, 2022

Whether you’re trekking to Everest Base Camp, climbing Kilimanjaro, or looking to do any travel over 2500m then you ought to understand the essentials of altitude sickness.

Suffering from altitude sickness or mountain sickness as it is sometimes called can seriously disrupt and curtail your trip and can lead to more serious life-threatening conditions. When I first visited the Himalayas back in the early 1990s, I was young, fit, and eager to climb big mountains. I knew nothing about altitude and how it might affect me. The older, more experienced, members of our team often remarked that we (the younger members) should slow down and take our time on the trek and take regular breaks and get good rest. That didn’t seem to make any sense, why walk really slowly and take ages to get where you are going when you can blast up the trail and then get your feet up? After only a few days of trekking and reaching just under 4000m I felt terrible. I had a banging headache, felt constantly sick, was totally off my food and permanently breathless. I had altitude sickness. I had to go back down and rest. When I felt better, I slowly ascended to re-join the team. Going slowly seemed to work and I wish that I’d listened to the advice I’d been given but when you are young and fit you think you are invincible!

A month or so after getting home from the Himalaya I flew out to Tanzania to climb Kilimanjaro. Putting what I’d learnt in the Himalayas into practice I thought I’d get to the top of Kilimanjaro without any problems, after all, I was still young and fit and now I’d mastered going slowly. I struggled and on summit night I had a terrible headache, couldn’t eat and was physically sick. I pushed on. Reaching the summit was amazing, but I was in no fit state to enjoy it. Even though I’d ascended slowly, I’d chosen the shortest and therefore cheapest route to the summit and in doing so, once again set the conditions for altitude sickness.

Not knowing about altitude sickness could, in the worst-case scenario, see your dream trip to wherever, ending abruptly. If you are lucky, you might get away with it, and suffer no symptoms of altitude sickness whatsoever. However, it’s more likely that if you don’t know anything about altitude sickness you’ll end up unnecessarily suffering and not enjoying your trip.

Quite literally, knowing about altitude sickness can be the difference between life and death!

In this article I’m going to draw on my experience to explain in a non-scientific, non-medical, easy to understand way, what altitude sickness is, who gets it, what the symptoms are and how to treat it.

What is altitude sickness? Altitude sickness is an ailment which can develop when you travel to high altitude, where oxygen levels are lower than what you are used to. Altitude sickness is also known as Acute Mountain Sickness (AMS), Acosta disease, Puna and Soroche.

Who gets altitude sickness? Anyone travelling to altitudes above 2500m can suffer from altitude sickness regardless of age, gender, or physical fitness. A previous successful ascent to altitudes above 2500m does not mean that you won’t become ill during a subsequent ascent.

What are the symptoms of altitude sickness? The main symptom of altitude sickness is a headache, but this is also the main symptom of dehydration, another common problem when trekking. People suffering from altitude sickness generally have a headache and one or more of the following symptoms: loss of appetite, nausea, vomiting, dizziness, and shortness of breath. Symptoms may not be immediately evident and can often come 6 to 24 hours after arriving at altitudes above 2500m and are commonly worse at night.

Why do people get altitude sickness? At sea level the concentration of oxygen in the air we breathe is about 21% and the air is relatively thick (the molecules we breathe in are close together). As we climb higher the concentration of oxygen remains the same, however, the air becomes thinner (the molecules we breathe in are more spread out) which means when we breathe in, we are breathing in less molecules of air and therefore less oxygen. By the time we reach altitudes of around 5500m we breathe in about half the amount of oxygen we would breathe in at sea level. So, to function, as we ascend, we need to breathe faster to compensate for the reduced oxygen levels, this in turn means that our heart must work harder to circulate blood containing less oxygen around the body. The good news is that our bodies can adapt to lower oxygen levels, but they need time to do so. So, the main cause of altitude sickness is ascending too quickly.

What is the treatment for altitude sickness? The only effective treatment consists of three elements: descent, descent, and descent. If you are suffering from altitude sickness, then the best thing you can do is to go down to a lower altitude and then rest until symptoms disappear. Once you are symptom free then it should be ok to continue with your journey. Quite often symptoms such as a headache and loss of appetite manifest themselves at the end of the day shortly after arriving at your destination. The first course of action is to make sure you are adequately hydrated, keep warm and get plenty of rest, taking paracetamol or Ibuprofen for your headache if required. That said, if symptoms do not ease then you should consider descending. Failure to recognise the symptoms and take action to prevent them worsening can lead to the more serious, life-threatening conditions of HACE and HAPE.

So, to summarise, anyone travelling to altitudes above about 2500m can get altitude sickness regardless of age, gender, and physical fitness. Suffering from a headache accompanied by one or more of the following symptoms: loss of appetite, nausea, vomiting, dizziness, and shortness of breath most likely means you have got altitude sickness. The best way to treat this condition is to descend to a lower altitude.

Getting altitude sickness isn’t a smart move but the good news is that it’s easy to avoid. In the next article I’ll give you my five top tips for avoiding altitude sickness and having a successful and truly memorable trip.