Altitude sickness is the main fear of people thinking about Everest Base Camp or Kilimanjaro. That is understandable. The good news is that, in most cases, it can be prevented with the right pace and by paying attention to the signs.
This article is not medical advice. Before any high-altitude trek, see a doctor, ideally one who specialises in travel medicine.
What happens to your body
Above roughly 2,500 m the air holds less oxygen, and your body needs time to adapt. The first signs are a headache, nausea, tiredness and restless sleep. If the symptoms get worse, the only safe treatment is to go down.
What I felt
The first time, I felt the altitude as a headache above 3,500 m. It is the most common sign and, most of the time, it passes with rest, water and patience. What matters is not to ignore it and to say so straight away.
What an acclimatisation day looks like
The rule is simple: climb high, sleep low. On an acclimatisation day on the way to Everest Base Camp, we climb at least 500 m above the altitude we come back down to for the night. Your body gets a signal of higher altitude, then has the night lower down to recover.
What we check every day
- How you feel overall: whether you have a headache, nausea or dizziness.
- Your sleep: how well you slept.
- Your oxygen saturation, with a pulse oximeter.
None of this works without honesty. A participant who hides a headache so as not to slow the group down is harming themselves and the group.
Who decides when someone goes down
The decision is taken together with the local guide and the person who is unwell. So far I have never had a situation in which someone had to go down or be evacuated. That does not mean we are not ready for one: that is why insurance with helicopter evacuation is compulsory.
Diamox and other medicines
About Diamox and any other medicine at altitude, I tell participants the same thing: see a doctor, do not ask for random advice. Your doctor knows your history and decides whether and how you take it.
Everest compared with Kilimanjaro
On the way to Everest Base Camp you have more days to get used to the altitude, so there are usually fewer symptoms. On Kilimanjaro the climb is faster and your body has less time to adapt. That is exactly why the Kilimanjaro programme has an acclimatisation day.
Practical advice
- Drink at least 3 litres of water a day.
- Sleep as much as you can, ideally more than 8 hours.
- Walk slowly, even when you feel fit.
- Say straight away if something is not right.
At altitude there are no prizes for arriving first. There is only the next day, which you want to start well rested.
