Altitude sickness might not be something you’ve had to contend with on many previous trips, but it’s pretty much part and parcel of any adventure through Bolivia, Chile, Colombia, Ecuador, or Peru. In fact, many of South America’s premier tourist destinations, like Cusco, Lake Titicaca, and La Paz, rise well above 2,500m (the typical threshold for altitude sickness).
I wrote an incredibly detailed post on preventing and treating Acute Mountain Sickness and High-Altitude Cerebral/Pulmonary Oedema when trekking at elevation, but it’s also important to acknowledge that altitude sickness and its various symptoms can affect visitors to South America even if they never set foot in the mountains. I’ve spent nearly 6 months travelling South America, plus done all the scientific research for you— here’s everything you need to know about altitude sickness and how to keep it from impacting your trip.
Decreased barometric pressure at high elevation, which in turn decreases the availability of oxygen in the air, triggers a host of altitude-related physiological responses to occur in our bodies. In plain English: there’s less oxygen in the air at high altitudes, which can lead to a number of unpleasant symptoms. Minor altitude sickness can occur anywhere above 2,500m, but the higher you get, the higher the risk of developing more serious symptoms.
Acute Mountain Sickness (AMS): a common but typically minor condition that includes a headache and other symptoms of fatigue or nausea
High-altitude Cerebral Oedema (HACE): commonly referred to as “brain swelling”, this is a life-threatening progression of untreated AMS, but usually only occurs at extreme elevation
High-altitude Pulmonary Oedema (HAPE): also a life-threatening condition characterised by fluid accumulation in the lungs, but usually only occurs at extreme elevation
Just to reiterate: if you’re sticking to the cities and the main tourist attractions of South America, you might experience minor symptoms of AMS, but thankfully the chance of serious complications is pretty low. If you’re doing some high altitude trekking, though, you definitely need to read my other post on altitude sickness, which includes heaps more detail about prevention and treatment of severe AMS, HACE, and HAPE.
What does it feel like to be at high altitude?
For the first few days in Cusco and La Paz, the cities where I personally felt most affected by altitude during my first trip to South America, I was a bit lightheaded if I stood too quickly, my stomach felt unsettled after meals, and I struggled to walk up stairs without panting — basically, I just felt really unfit. These are all totally normal physiological responses to arriving at altitude, and they passed as soon as my body acclimatised. You can probably expect similar symptoms in your first few days at altitude, but don’t fret, none of these things mean you are actually experiencing altitude sickness.
According to recent research, only about 17% percentage of travellers to 3,400m (e.g. Cusco, Peru) will experience severe altitude sickness. In milder cases, AMS is not too dissimilar to a bad hangover— expect a headache, feelings of dizziness or nauseous, difficulty eating, and just general exhaustion. In worse cases, you might experience vomiting and diarrhoea. Although it’s not necessarily the norm, altitude sickness can even interrupt your travel plans, so you should aim to recognise AMS early and take appropriate preventative/treatment steps (discussed later in this post).
The important thing is just to take it easy for a few days when you arrive at altitude and give your body time to adjust. This means it’s probably not a great idea to jump off the bus in Cusco and go for a hike immediately, nor is it a good idea to sign up for an active day tour of Lake Titicaca if you aren’t fully acclimatised. Keep this in mind when you’re planning your trip— allowing a few days to relax and explore the city at a slower pace before jumping into all the adventure will help you avoid (or at least minimise the risk of) altitude sickness.
Normal responses to altitude
Shortness of breath during activity
Periodic breathing (intermittent periods of sleep apnoea, where you stop breathing and wake yourself up— everyone will experience this above their own altitude “threshold” and it is completely unrelated to any altitude sickness, although it can be a bit alarming if you aren’t aware of it!)
Frequent need to pee
Symptoms of altitude sickness
Headache (this is the hallmark of AMS— if you don’t have a headache, you are probably just experiencing a normal response to the altitude)
Loss of appetite
Fatigue or lethargy
Light-headedness or dizziness
Will I get altitude sickness?
There are several risk factors associated with developing altitude sickness, but it’s really interesting to note that physical fitness actually has nothing to do with it— you can be the fittest person in the world, but it doesn’t mean you’ll be more prepared for altitude than anyone else. Regardless of fitness, it’s important to consider the risk factors for altitude sickness and take steps to prevent it on your trip.
Risk factors for altitude sickness
It goes without saying that the higher a city is in elevation, the higher your chance of developing altitude sickness— about 34% of travellers who ascend above 5,000m will develop AMS. Check out the elevation of some popular destinations in South America below.
Rate of ascent
Flying from Lima to Cusco or La Paz represents an ascent of about 3,500m in just a few hours, which can often trigger altitude sickness.
If you haven’t properly acclimatised to the altitude before doing physical activity (e.g. hiking the Inca Trail on your first day at elevation), you’ll be at a greater risk of developing altitude sickness.
Unfortunately, some people are just more prone to altitude sickness than others, but this is something you won’t know until you’ve actually travelled to high altitudes.
The individual risk of altitude sickness depends on your itinerary and on your own susceptibility— no two people will experience the same symptoms at the same time in the same way, and you just won’t know how your body is going to react until you’re actually there. Which means it’s best to be prepared!
Elevation of popular destinations
So many travellers are worried about altitude sickness at Machu Picchu, but the ancient citadel actually sits below 2,500m (at 2,430m), so it’s extremely unlikely that you’ll feel the elevation at all! Here are some popular destinations in South America where you do need to consider the altitude:
There are a few simple, common-sense ways to prevent serious altitude sickness from interfering with your trip or leaving you sick in bed. Some of these need to be considered at the trip planning stage (such as adding extra days to your itinerary), but there are also some simple things you can do on the trip to help keep altitude sickness at bay.
Tips for preventing altitude sickness
Arrange your itinerary in such a way that you are starting in lower elevation cities and working your way towards higher elevation destinations (e.g. Lima to Arequipa to Cusco to Lake Titicaca). This will help you get used to the altitude slowly and minimise the shock to your system.
Leave a few free days at the start of your itinerary where you can just bum around town and get a feel for the altitude. This will help your body acclimatise before you go any higher in elevation.
Take it easy
It’s important to know your own limits and listen to your body, because you absolutely do not want to ruin your trip by developing severe altitude sickness. Rest often, especially during those first few days, and don’t be surprised when you can’t move at your normal pace. It gets better with time!
Drinking lots of water doesn’t do anything to help prevent altitude sickness per say— but many symptoms that mimic altitude sickness (e.g. dizziness) are actually related to dehydration. As a result of the altitude, we also tend to pee more frequently and lose more liquids to sweat evaporation than usual, so it’s extra important to stay hydrated.
Sadly, alcohol can exacerbate symptoms of altitude sickness, so it’s best to skip the beers and pisco sours, at least for your first few days at elevation.
Chew coca leaves
Andean natives have been using coca for more than 3,000 years to alleviate symptoms related to altitude, and bags of coca leaves, coca tea, and even coca candy are now ubiquitous in all of South America’s high-altitude cities. There’s no concrete scientific evidence to suggest that coca leaves are an effective prevention strategy for altitude sickness, but they absolutely help manage the symptoms!
* Just a quick disclaimer that I am not a medical doctor, but I do have a PhD in the medical sciences— I conducted a review of the existing literature and all of the information provided here about altitude sickness is directly from peer-reviewed medical journals. Still, you should consult with a doctor about your specific trip and medical history before taking any medications.