Altitude Sickness in the Andes
What it is, how to recognize it, and what to do about it
I have lived fifty years in the Andes and guided photographers through them for thirty. Altitude is the one subject where I will not let a guest guess. Most people adjust to it without much trouble. Some take longer. A few cannot handle it at all, and that is not a failing, it is just how their body works.
What separates a rough first night from a medical emergency is almost always how early somebody speaks up. So this post is about recognizing what is happening to you, and knowing what to do next.
What altitude sickness is
Above roughly 2,440 m/8,000 ft the air pressure drops, and every breath carries less oxygen than the same breath at sea level. Your body answers by breathing faster and working the heart harder, and over the following days by making more red blood cells. Altitude sickness is what happens when you climb faster than that adjustment can keep up with.
It is not a fitness problem. Trained runners get it at the same rate as everyone else, and in thirty years of guiding I have watched older travelers handle altitude better than young athletic ones more often than not, because they pace themselves. Being fit decides how much of the trip you enjoy. It does not decide whether you get sick. Our challenge levels page goes into what that means for each of our tours.
The three altitude bands
High altitude: 2,440 to 3,660 m/8,000 to 12,000 ft
Very high altitude: 3,660 to 5,500 m/12,000 to 18,000 ft
Extreme altitude: above 5,500 m/18,000 ft
Almost all of our work happens in the first two bands. Cusco, the gateway to the Sacred Valley in Peru, sits at about 3,400 m/11,150 ft. Quito in Ecuador is lower, around 2,850 m/9,350 ft. La Paz in Bolivia is the unusual one: the city spans roughly 900 m of vertical, from about 3,100 m/10,170 ft in its lowest neighborhoods to 4,061 m/13,320 ft at the El Alto rim where the airport is. No other city in the world does that, and we use it deliberately.
Three different illnesses, not three stages
This is the part most articles get wrong. AMS, HAPE and HACE are not rungs on a ladder that you climb in order.
AMS, acute mountain sickness, is the common one. It usually shows up 6 to 12 hours after arriving at a new elevation. A headache plus some combination of fatigue, no appetite, nausea and poor sleep. It is unpleasant and it usually settles on its own in one to three days, provided you stop going up. That last part is the whole treatment: go no higher until the symptoms are completely gone.
HAPE is fluid in the lungs. It is uncommon on a properly paced ascent. The first reliable sign is breathlessness at rest, not breathlessness while walking. Then a cough that turns wet or frothy, and a sudden drop in what you are able to do. HAPE is the most common cause of death from altitude illness, and it can arrive in someone who never had a headache at all.
HACE is swelling of the brain. It is uncommon, and it usually does follow AMS that was ignored. The classic sign is loss of coordination. Ask the person to walk heel to toe in a straight line. Confusion and a severe headache come with it. It is the most immediately life-threatening form.
The two severe forms can occur together. Either one is an emergency, and the treatment for both begins with going down.
What actually raises your risk
How fast you go up is the dominant factor, and it is the one an operator controls. That is why our itineraries look the way they do, and it is covered in detail on our high altitude information page.
Your sleeping elevation matters more than the highest point you reach during the day. You can stand at 4,500 m for an hour and be fine. Sleeping there is a different question.
A previous episode of altitude illness makes another one more likely, so tell us if you have had one. Body weight is its own risk factor, separate from fitness, and the research is reasonably consistent that it raises the odds. And there is a large amount of plain individual variation that nobody can predict in advance, including me.
What helps, and what does not
Arrive early if you can. A night or two at moderate elevation before the trip starts is the single most useful thing you can do on your own.
Drink water, but do not force it. You want your urine pale, not colorless. Overhydrating is its own problem.
Go easy on alcohol for the first few days, particularly at night, when it interferes with the breathing pattern you need while you sleep. Eat carbohydrates, which are easier to process at elevation, and keep heavy meals away from bedtime so they do not cost you a night of rest.
Talk to your own physician about acetazolamide, sold as Diamox, well before you travel. It genuinely helps some people and it is not right for everyone, particularly anyone with a sulfa allergy. That assessment is your physician’s to make, not ours, and it needs to happen before you leave rather than in a hotel lobby in La Paz.
On coca tea, I will be straight with you. It is part of daily life across the Andes and you are welcome to enjoy it. It does not prevent altitude illness and it does not treat it. Anise and chamomile tea are just as pleasant and will not put a trace of anything in your system if your work tests you for drugs.
When to go down
Descent works. It is the one treatment that always works, and the only one that reliably works in a remote place.
If symptoms appear, go no higher until they have gone completely. If symptoms get worse, or any severe sign appears, go down. Do not sleep on it and do not wait for morning. Out here the plan is self-rescue, and helicopters cannot be assumed in most of the places we work, so the margin you have is the one you keep by going down early. This is also why we require emergency medical and evacuation insurance before you travel with us.
Tell somebody early
The most useful thing you can do for yourself is say something at the first sign. Not at the worst sign. I would far rather change the plan for a day than manage an emergency, and no guest has ever been made to feel awkward for speaking up. Changing a day is easy. Getting somebody off a mountain at night is not.
Altitude is not something to conquer. It is a condition you work with, and when the pacing is right most people barely notice it after the first couple of days. That is the whole aim: get the adjustment out of the way early, so the rest of the trip is about the photographs.
The full detail, including what we carry, what we watch for and how each country’s itineraries are built, is on our high altitude information page.
