Altitude: give yourself time to enjoy it

Three altitudes not to confuse

To plan a trip, you need to distinguish three things: the altitude where you sleep, that of the roads you cross, and that of the day excursions. The first matters most for getting used to the altitude; the other two matter mainly for the effort of the day. The CDC, the United States public health agency, puts it simply: a trip up to altitude with a return lower down in the evening tires the body far less than a night up there.

On the road from Arequipa to the Colca, the Patapampa Pass climbs to nearly 5,000 metres, often at dawn, before coming back down to sleep in Chivay. The crossing is short: a slight headache or shortness of breath are common there, and generally pass as you go back down. Wrap up warm, drink water and walk slowly at the viewpoint.

The body adapts in a few days

As you climb, the air always contains the same proportion of oxygen, but the pressure falls: each breath brings in a little less. At around 3,050 metres, according to the CDC, the pressure of the oxygen you breathe is only 69% of that at sea level; in Cusco or Puno, a little higher, it is slightly less again (CDC Yellow Book). A lung specialist at Peru’s Ministry of Health sums it up this way: “soroche” is not an illness in itself, but the body’s response to this air that is poorer in oxygen.

The body adapts, first by breathing faster and more deeply, then through other mechanisms: this is acclimatisation. According to the CDC, its first phase takes place over three to five days. It simply takes time, and good physical fitness cannot buy you that time: training does not change the risk. Having coped well with altitude on a previous trip is the best indication, provided you went as high and as fast; it is not a guarantee.

The first nights. Above about 2,700 metres, it is very common to sleep badly for the first few days, with irregular breathing and short pauses that wake you up. This is not a sign of illness, and it generally improves night after night.

Arriving by plane. Flying from Lima to Cusco means climbing more than 3,000 metres in an hour and a half. The body needs a few days to catch up: that is why the first days should stay calm.

When symptoms appear. Mild altitude sickness generally starts a few hours after arrival, between two and twelve hours according to the CDC. Without going any higher, it usually disappears within one to two days.

How many travellers feel it

It is common, and usually mild. Three surveys of travellers in Cusco give an order of magnitude:

Sources: Salazar and colleagues (2012), Pineda-Reyes and colleagues (2020), Caravedo and colleagues (2022). The gap between 2010 and 2017 is partly due to the criteria: the scale used since 2018 no longer counts sleep problems, which brings the figures down (Pineda-Reyes and colleagues).

Above all, these figures say that feeling the altitude is normal. In the 2017 survey, around one in five of those affected had to change their plans, by a day in bed or a missed excursion; the others carried on with their trip as planned. The two airport surveys also point to the same lesson: travellers who had first stopped somewhere lower, or in another high-altitude city, suffered less in Cusco.

The first night counts

The CDC classes the risk of altitude sickness according to the altitude where you sleep on the first night, for someone setting off from low altitude, with no serious medical history. It is a guide for choosing your first stop, not a verdict:

Above 3,000 metres, the CDC then advises not sleeping more than 500 metres higher than the previous night, and adding a night of acclimatisation for every 1,000 metres. It mentions Cusco specifically: you can go down to sleep lower than the airport for one or two nights before climbing again, which the Sacred Valley allows. A stay of at least two nights above 2,750 metres in the two preceding weeks also helps, if your trip lends itself to it.

The right pace: take your time

The most common trap is a programme that is too tight. For example:

• To avoid: day 1 in Cusco, day 2 at Machu Picchu, day 3 at Vinicunca (the Mountain of 7 Colours). Three very early starts, long drives, and the highest outing before the body has had time to get used to the altitude.
• Better: two quiet days in Cusco. You rest, walk slowly around the centre, visit the cathedral or the Qorikancha, drink a mate de coca and eat light. Then the Sacred Valley and Machu Picchu, then the big outings such as Vinicunca at the end of your stay, when you feel well.

A variant. If you prefer, go straight down to the Sacred Valley on arrival, a little lower (Urubamba or Ollantaytambo, about 2,800 m), for 2 to 3 nights, then Machu Picchu (about 2,400 m for the site, 2,000 m for the village), and only then Cusco (3,400 m). See Cusco and the Sacred Valley.

Via the south. Lima (sea level), Arequipa (2 to 3 nights, about 2,300 m), the Colca (Chivay, about 3,600 m), Puno (about 3,800 m), then Cusco. Arequipa lets you start lower; the road to the Colca climbs all at once, so keep a calm evening in Chivay. The circuit can also be done the other way round, from Cusco to Puno and then the Colca.

Towards Huaraz. The town is at about 3,050 m. Hikers usually spend two or three days there, with short walks, before Laguna 69 (about 4,600 m) or a trek. See Huaraz.

In every case, keep a spare day: you will be able to move an outing without breaking up the trip.

Day to day, up there

For the first few days, a few simple habits help. They are consistent from one source to another (CDC, Peru’s Ministry of Health, the British health service NHS):

• Slow down. Peru’s Ministry of Health advises resting for the first hours after arrival and no intense effort straight away; the CDC recommends light activity for the first 48 hours.
• No alcohol for the first two days. The CDC advises avoiding it for the first 48 hours.
• Coffee, as usual. If you drink it every day, carry on: stopping suddenly causes a headache that is easily confused with the altitude one (CDC).
• Light meals and enough to drink. Peru’s Ministry of Health advises light meals, in small portions, and drinking enough; the air at altitude is dry.
• Sun and cold. At altitude, ultraviolet radiation is stronger and the nights cold (CDC): sun cream, sunglasses, a hat, and a warm layer for the evening.
• Sleep. The first nights are often broken; it is nothing serious. Ask your doctor’s advice before taking a sleeping pill at altitude.

What you feel, and when to see a doctor

For the first few days, many travellers feel the altitude a little. This is normal, and it generally passes within a few days if you do not go any higher.

On the left is acute mountain sickness, the common and benign form. You slow down, stay at the same altitude, drink and eat light; for a slight headache, Peru’s Ministry of Health mentions a common painkiller such as ibuprofen. According to the NHS, symptoms generally improve within one to three days. The CDC rule is simple: never go up to sleep higher while you have symptoms, even mild ones.

On the right are rare but serious signs, which may point to high-altitude pulmonary oedema (breathlessness at rest, cough) or high-altitude cerebral oedema (confusion, balance problems). In that case there is no discussion: you go down with someone and see a doctor. The NHS advises going down 300 to 1,000 metres if symptoms get worse or do not improve after a day, and Peru’s Ministry of Health insists: faced with severe discomfort that does not ease with rest, the most effective step is to go back down. If symptoms do not pass with rest and a painkiller, it advises going to the nearest health centre (MINSA).

What to remember: you do not go up to sleep higher until you feel well; if the symptoms get worse instead of passing, you go back down. And travel with insurance that covers medical costs and repatriation: outside the big cities, medical care is limited. In an emergency, SAMU answers on 106.

Medicines: a medical decision

There are medicines that prevent altitude sickness, but they are not something to take on your own initiative. The most widely used, acetazolamide, is prescription-only: Peru’s Ministry of Health points out that it should not be taken without a prescription. The CDC recommends it mainly for travellers at moderate or high risk, for example when a rapid ascent cannot be avoided; it also mentions ibuprofen, which is less effective as prevention. The doctor decides according to your itinerary, your medical history and your treatments.

Locally, you may be advised to take tablets or remedies against “soroche”. Ask a doctor or pharmacist for advice before taking any, especially if you are already on medication.

Before you leave

In good health, most travellers need nothing more than a quiet pace. Still ask your doctor’s advice, with your day-by-day itinerary, if:

• you have heart or lung disease, or have had altitude sickness before;
• you have high blood pressure or a heart rhythm disorder: Peru’s Ministry of Health advises travelling with all your medication and after a recent check-up;
• you are just over a respiratory infection: according to a lung specialist at Peru’s Ministry of Health, it makes pulmonary oedema more likely;
• you have severe sleep apnoea or diabetes: the CDC notes that some blood glucose meters are less accurate at altitude;
• you are pregnant: the CDC advises avoiding sleeping above about 3,050 metres;
• you are travelling with young children: they are as sensitive as adults, and toddlers show it through irritability, crying, loss of appetite or paleness;
• you are planning a trek of several days or outings above 4,500 metres.

They can talk to you about a possible preventive medicine, which is prescribed case by case. This page does not replace their advice.

Treks and outings above 4,000 metres

On a trek, it is not the pass that matters most, but the altitude of the camps, and the number of days spent getting used to the altitude before setting off. A few reference points:

Plan a few days in the starting town before setting off, choose an agency that knows how to adapt the pace and turn back, and tell them straight away if you do not feel well: it is not a failure, it is the basic rule in the mountains. See choosing your hike.

What about the coca leaf?

You will be offered it everywhere: as an infusion, mate de coca, often served at hotel receptions in Cusco, or as leaves to chew. Many Peruvians and travellers say it helps them cope with the altitude, and a cup on arrival is almost part of the trip. Think of it as a traditional aid rather than a medicine: it does not replace two quiet first days. See coca leaf.

A few misconceptions

“If I am fit, I am not at risk.” Physical fitness does not protect against altitude sickness; the pace does.

“Machu Picchu is the highest point of the trip.” No: the site is lower than Cusco, and the village of Aguas Calientes lower still.

“I had nothing last time, so I will have nothing this time.” It is a good sign if you went as high and as fast, but not a guarantee.

“A breath of oxygen and off you go.” A small can brings brief relief; it does not replace rest or, if it does not pass, going down.

A flexible programme and suitable support are worth more than a goal kept at all costs.