Why you should always acclimatise when going to high altitude.
This post is for those who have no or little experience with high altitude. It’s designed to help you understand the basics of high altitude travel, altitude sickness and acclimatisation. It is not medical advice.
What is High Altitude?
High Altitude is considered anywhere higher than 2500m above sea level. It is at around this height where altitude sickness can start to affect you. The higher you go, the higher the risks and greater are the issues.
Depending on where you live and where you’ve travelled, you may have never experienced high altitude and its effects before. For example, in Australia, the highest summit is Mt Kosciuszko which is 2228m above sea level.
Flying in a plane doesn’t count as planes are pressurised at or below 2400m above sea level to prevent any issues for the crew and passengers.
When travelling South America, due to the Andes mountain range, some of the highest altitudes most tourists will come across are in Peru, Colombia, Bolivia, Northern Chile and Ecuador.
Why is High Altitude an issue?
The higher you go, the less air pressure there is. Less air pressure means the air has less oxygen molecules in it. Less oxygen = bad news for things that require it.
i.e. you
Upon arrival at a high altitude location, activities such as walking up a gentle slope or a flight of stairs are now much harder as your body has to work harder to supply it with the necessary oxygen.
Normal effects of high altitude include shortness of breath since the lungs have to work harder to deliver oxygen around.
But given that easy activities are now hard, imagine what ‘hard’ activities like a trek would be like? Your body is already working overtime to supply enough oxygen, pushing it harder could mean not delivering enough oxygen around.
What is Altitude Sickness?
The vast majority of people will experience a mild form of it with the most common being a headache. The next degree is a headache combined with one of nausea, vomiting, fatigue, dizziness or sleep issues.
Those are the annoying ones and usually* resolve by going lower in altitude, resting or not climbing higher. I saw people get sick then better halfway through a trek (resting overnight, campsite is lower than the day’s hike).
*I say usually because the latter can be in a severe form and needs treatment.
A very small percentage can experience even more serious conditions such as HAPE and HACE. I’ll spare you the details so you’re not confused – the important thing to know is that they are life-threatening.
That’s why there’s a huge fuss about acclimatisation. It helps your body adapt to the high altitude thus preventing or minimising the risks of altitude sickness (including the life-threatening types).
What is Acclimatisation?
Acclimatisation is getting your body used to higher altitudes gradually. It can take days or even weeks for your body to acclimatise completely. Some people just seem to adapt to it more quickly than others.
The issue is a shortage of oxygen which your body will make up for on its own by producing more haemoglobin over time to carry more oxygen around in your blood. That gentle slope isn’t so bad again.
When and how do I Acclimatise?
By merely being at high altitude, your body will begin to acclimatise on its own.
For this reason, a lot of tour operators will tell you to wait 1-2 days before departing on anything strenuous that takes place at higher than 2500m. For example, in Cusco, they will tell that you should wait (not necessarily doing nothing) for about 2 days to acclimatise before departing on any treks to Machu Picchu. In addition, if anything serious does occur (unlikely) while you are resting about town, you’ll be able to get immediate medical assistance.
In practice, the onus is on you to take the necessary precautions as there are no checks for acclimatisation (at least where I’ve been).
There are also active steps you can take and the following is simply my observation.
I’ve noticed most people I’ve met do 1-2 days acclimatising in town before heading out to do more strenuous activities. Nobody has weeks of vacation to sit around and acclimatise to an optimal level. Once they’ve done the initial wait, going from easier to harder is typically how they would proceed. For example, a lot of people use the Laguna 69 hike as practice for the 4-day Santa Cruz trek in Huaraz. People I’ve met used the 4-day Santa Cruz trek as practice for the 8-day Huayhuash trek which is minimum 4100m – very high altitude. This way they are slowly exposing themselves to more and more altitude for longer durations over time.
A guy I met who did Everest Base Camp mentioned 1 week of acclimatisation.
I’m fit, no problem, right?
Wrong. Everyone reacts to high altitude differently and although physical fitness will help you get through a trek, it will not protect you from altitude sickness.
Medication to help
Diamox (Acetazolamide) can help with both preventing and overcoming some types of altitude sickness. Reputable guides on treks will always carry something like this in case of emergencies. You may be able to acquire some in your home country – speak to your doctor. Some people I met carried this, I found no need to.
Hearsay advice is that coca candy or chewing coca leaves can help, but this hasn’t been proven.
Altitudes of common locations in South America
Peru
Lima: ~100m
Cusco: 3400m
Machu Picchu: 2430m
Arequipa: 2335m
Huaraz: 3052m
Inca Trail: 2400m-4200m
Salkantay Trek: 1900m-4650m
Laguna 69 Hike: 3800m-4600m
Santa Cruz Trek: 3800m-4750m
Huayhuash Trek: 4100m-5000m
Chile
San Pedro de Atacama: 2400m
Torres del Paine O Trek: 1200m
Bolivia
Salar de Uyuni: 3650m
La Paz: 3640m
Colombia
Bogota: 2640m
Ecuador
Quito: 2850m
… and for reference
The extreme end of the scale is Mt Everest (8848m) where people frequently die.
Further reading
If you want to know more, this site goes into a lot of detail: