The simplest way to handle altitude in Peru is to sleep lower first and go higher later. Flying from Lima straight to Cusco, at about 3,400 m, is the sharpest jump, so many itineraries drop to the Sacred Valley floor, at about 2,800-2,900 m, for the first nights and visit Cusco afterwards. Machu Picchu itself is lower, at about 2,430 m, and is usually easier than Cusco.
The sections below give three sample sequences, the high days that reach about 4,500-5,000 m, daily habits that help, and the symptoms that mean you should descend and see a doctor. This is general information, not medical advice: talk to a doctor or travel clinic before you go.
Why the order of your days matters
Altitude sickness depends mainly on how fast you rise and how high you sleep, not on fitness. A marathon runner can feel unwell at Cusco while an unfit traveller feels fine, and nobody can tell in advance which one they will be. That is why itineraries are built around sequence: the same places in a different order can feel very different.
The general principle is to gain height in steps and to sleep as low as the plan allows in the first nights. The body adjusts over days, and there is no way to speed that up reliably. Most visitors feel a few mild effects in the first day or two, such as a headache, breathlessness on stairs, poor sleep or a slightly raised heart rate, and these usually ease. The page on altitude sickness covers symptoms and causes, and sleeping at 3,400 m describes what the first nights are often like.
The altitudes that shape a Cusco-region trip
A few reference heights help in planning. Cusco sits at about 3,400 m. The floor of the Sacred Valley is lower, at about 2,800-2,900 m, with Urubamba at about 2,870 m and Ollantaytambo at about 2,790 m. Machu Picchu citadel is at about 2,430 m, and the town of Aguas Calientes below it at about 2,040 m, so the famous site is a descent, not a climb, from Cusco.
Further south, Puno is at about 3,830 m and Lake Titicaca at about 3,810 m, higher than Cusco. In the other direction, Arequipa is at about 2,330 m and Huaraz at about 3,050 m. Day trips and treks then add height: Rainbow Mountain reaches about 5,000 m, and the Salkantay pass is at about 4,600 m. See Cusco and the Sacred Valley for the base towns, and altitude at Machu Picchu for the citadel itself.
Sequence A: fly to Cusco, go straight down to the valley
This order suits most people arriving from Lima, and is common on itineraries for first-timers. On day one, fly in and transfer straight to the valley floor without lingering in Cusco. Keep the afternoon light: a short walk, a meal, an early night. Avoid alcohol and heavy food, drink water regularly and expect a restless sleep.
On days two and three, explore the valley at a gentle pace, visiting villages and ruins that involve little climbing. Stay at the valley level for two nights or more if the schedule allows. Then move to Cusco, at about 3,400 m, for the city days, which now start from a partly adjusted body. Machu Picchu fits easily at the end of the valley stay or after Cusco, since the site is lower than both. For the transfer details, see Lima to Cusco and how the Sacred Valley compares with Cusco as a base.
Sequence B: Cusco first, then the valley
Some travellers prefer to land in Cusco and stay, for reasons of time, a booked tour or a fixed hotel. This works, but the first day needs care. Treat it as a rest day: check in, walk slowly in the historic centre, keep meals light, drink water and sleep. Leave steep climbs, such as the hill to the ruins above the city, for day two or three.
After two or three nights in Cusco, move down to the valley, where most people sleep better. Machu Picchu then follows with the body adjusted. The drawback of this order is that the hardest sleeping altitude comes first, when you have had least time to adapt. Travellers with a history of altitude trouble, with heart or lung conditions, or who are pregnant, should ask a doctor before choosing it. A short stay can also be extended: if the first night goes badly, many people simply move down the next day. See the sample plans in 7 days and 10 days.
Sequence C: Lake Titicaca and Puno
Puno and Lake Titicaca, at about 3,810-3,830 m, are higher than Cusco, and a route that starts there asks more of the body. The best answer is to arrive from a lower place: from Arequipa, at about 2,330 m, or after some days in Cusco, not straight from the coast. Overland routes that climb slowly through the day give more time to adjust than a flight.
Plan the first day at the lake as an easy one, with a gentle walk and early night, and do the boat tours on day two. Islands on the lake involve steps and cold wind, so go slowly. Nights at Puno are cold, which makes sleep feel worse than it is. If you can choose, put Titicaca after Cusco, so that you reach the highest sleeping altitude of the trip with several days of adaptation behind you. See Puno and Lake Titicaca for the practical side.
High days: Rainbow Mountain and Salkantay
Some of the most popular excursions go much higher than anywhere you sleep. Rainbow Mountain reaches about 5,000 m and the Salkantay pass about 4,600 m, so time spent above 4,500 m is short but demanding. These days are best placed after several nights in the Cusco region, not on the first or second day, and ideally after a smaller high outing as a test.
On the day, go slowly, rest often and carry water and warm layers, since the weather changes quickly. Turning back is a sensible decision, not a failure; the guide and the operator should say that clearly in advance, and it is worth asking. Do not take a high-altitude day when you already feel unwell at lower height. See Rainbow Mountain and acclimatisation for treks for the preparation and the route details.
Day-to-day habits that help
A few habits are widely recommended for the first days. Drink water regularly, eat lightly, keep activity gentle and avoid alcohol until you feel settled, since it can worsen sleep and dehydration. Rest rather than push through a headache. Sleeping lower is the most reliable adjustment of all, when the plan allows it.
Coca tea (mate de coca) is a common local custom at altitude, offered in hotels and cafés, and many visitors drink it. Whether it reduces symptoms is not firmly established, so treat it as a tradition, not as a treatment, and be aware that coca products can show up in drug tests and may be restricted in some countries. Ask a doctor or travel clinic before the trip about preventive medication, which is a medical decision that depends on your health and other medicines; this page gives no names or doses. Check health and vaccines for what else to prepare.
Machu Picchu, the Inca Trail, children and older travellers
For most people, Machu Picchu is the easiest part of the trip for altitude, because it lies at about 2,430 m and the base at Aguas Calientes is lower still. The effort at the site is steps and walking, not thin air. The Inca Trail is different: it crosses passes up to about 4,200 m and the second day is the hard one, so arrive in Cusco several days early.
Children can get altitude sickness and may not describe it well; look for unusual tiredness, irritability, refusing food or vomiting, and go down if they worsen. Older travellers are not necessarily more at risk, but heart and lung conditions matter, so see a doctor before booking a route that starts high. Both groups usually do better with the valley-first order and a slower first week. See the pages on families and senior travellers.
Frequently asked questions
Should I go to Cusco or the Sacred Valley first?
For most people the Sacred Valley first is the gentler option, because it is roughly 500-600 m lower than Cusco. Cusco first also works if you keep the first day very light. The key is the first night's sleeping altitude, not the order of sightseeing.
How many days does it take to adjust to altitude in Peru?
Most people feel the worst of it in the first one or two days, and many feel settled after about two to three, though this varies from person to person. There is no reliable way to predict who will be affected. Plan the first days so that you can slow down if you need to.
Is Machu Picchu high enough to cause altitude sickness?
It is much lower than Cusco, at about 2,430 m, so it rarely causes trouble on its own. Problems usually come from the days before it, or from the hiking on the way. The base town, Aguas Calientes, is lower again, at about 2,040 m. See altitude at Machu Picchu.
Is coca tea safe and does it work?
Coca tea is a traditional drink in the Andes and widely served at hotels. Evidence that it prevents or treats altitude sickness is limited. It can also cause problems in drug tests, so ask a doctor if that matters for you.
Can I take medicine to prevent altitude sickness?
There are preventive medicines, but whether one suits you depends on your health, allergies and other medicines. Ask a doctor or travel clinic well before departure. Never take someone else's tablets or guess at a dose.
What should I do if I feel unwell at altitude?
Rest, drink water and avoid going higher until the symptoms ease. If they are severe or worsening, such as vomiting, confusion, unsteady walking or breathlessness at rest, go down at once and seek medical help. Descending is the most effective step.
Is Puno harder than Cusco for altitude?
Puno is higher, at about 3,830 m, against about 3,400 m for Cusco, and the nights are cold. It is easier if you arrive after some days at Cusco or from Arequipa. See Puno for more.
Can children and older people travel to Cusco?
Yes, many do, usually with a slower first week and the valley-first order. Children may not say that they feel ill, so watch for tiredness and loss of appetite. People with heart, lung or blood-pressure conditions should speak to a doctor first.