Health and Safety in Peru: Altitude Is the Real Risk

Why altitude hits harder here than the numbers suggest

Cusco sits at roughly 3,400 metres and Puno, on Lake Titicaca, higher still at around 3,800. Those are serious elevations, but plenty of people visit comparable heights elsewhere without difficulty. What makes Peru different is the approach. Lima is at sea level, the flight to Cusco takes about ninety minutes, and a traveller can go from a Pacific breakfast to walking up a cobbled street at 3,400 metres before lunch. Trekkers who reach similar heights on foot have spent days doing it; the aircraft removes every one of those days.

The result is that a large proportion of visitors feel genuinely unwell in their first day or two — headache, breathlessness on gentle slopes, poor appetite, disturbed sleep, a heart working visibly harder than it should for the effort involved. This is the body responding to less oxygen per breath, not a verdict on fitness. If anything, fit and energetic travellers fare worse, because they do more on arrival day and their capacity to push through masks the signal they should be listening to.

Two consequences shape a Peruvian itinerary more than any other planning consideration. Arrival day is a rest day, not a sightseeing day — and building it in deliberately is the difference between losing one afternoon and losing three. And the high-altitude excursions that tour desks sell as day trips from Cusco are considerably higher than Cusco itself, so they belong at the end of a stay rather than the beginning.

What actually helps

Go up more slowly if the itinerary allows it. The Sacred Valley floor sits several hundred metres below Cusco, and spending the first night down there before moving up to the city is the single most effective piece of routing available — it costs nothing, it changes nothing else about the trip, and experienced operators build it in as standard. If your first night must be in Cusco, treat that day as genuinely empty: a flat walk, an early dinner, a long sleep.

Beyond routing, the behavioural rules are simple and they work. Drink far more water than feels necessary, because the dry mountain air dehydrates you faster than you notice and dehydration makes every symptom worse. Eat lightly and often rather than heavily. Skip alcohol for the first day or two — a drink at 3,400 metres does considerably more than the same drink at sea level. Walk slowly, particularly uphill, and stop before you need to. Sleep with your head slightly raised if you can.

On medication there is only one sound instruction: talk to a doctor or a travel clinic before you go. Drugs used for altitude are prescription medicines with real contraindications and interactions, and the decision depends on your health, your route and how fast you intend to ascend. Ask well before departure rather than in a pharmacy on arrival day, which is where a great many visitors end up making it badly.

Coca is a separate matter and worth understanding rather than avoiding. Coca leaf and coca tea are legal, ordinary and everywhere in the Andes — offered free in hotel lobbies, sold in every market, chewed and brewed by people who live at these altitudes and have for millennia. Whatever you conclude about its effects, it is part of the culture you are visiting and refusing it as though it were illicit misreads the situation. Two practical points, though: coca can produce a positive result on a drug test for some time afterwards, which matters if your work involves them; and carrying leaf or tea out of the country is a customs question with real consequences in many jurisdictions, regardless of how freely it is sold here.

When it stops being discomfort

Ordinary altitude discomfort is unpleasant and self-resolving: it appears in the first day, peaks somewhere in the first two, and fades as the body adapts. What matters is recognising the point at which it is no longer that. Symptoms that get worse rather than better after the first day, that do not improve with rest, or that go beyond headache and breathlessness into confusion, loss of coordination, breathlessness while sitting still, or a persistent cough are a different situation and need medical attention rather than patience.

The response in that case is not complicated and it is the only one that reliably works: go down. Descent is the treatment, altitude is the cause, and every hour spent hoping it passes is an hour not spent doing the one thing that helps. Tell someone — your guide, your hotel, your travelling companion — rather than quietly enduring it, because the early signs are much easier for another person to notice than for the person experiencing them. Cusco and Puno both have clinics used to exactly this, and hotels know where they are.

Anyone with a heart or lung condition, anyone pregnant, and anyone with sickle cell trait should take medical advice specifically about high altitude before committing to a Peruvian itinerary, because the standard advice above is written for healthy adults and these are situations where it may not apply.

Sun, water and stomachs

The sun at these altitudes is fiercer than it feels. There is less atmosphere filtering it, the air is cool enough that you do not register heat as a warning, and the burn arrives quickly — on the back of the neck, on the ears, through cloud. High-factor sun protection, a brim and sunglasses are not optional above three thousand metres, and the reflected light off water at Titicaca or off snow on a pass adds to it considerably.

Drink bottled or properly treated water rather than tap throughout the country. A few days of stomach trouble is the commonest traveller complaint here as everywhere, and the usual precautions cut the odds substantially: be more careful with raw salads and with juices made using unknown water, prefer food cooked hot and served promptly, and wash or sanitise hands before eating. Ceviche is a special case worth addressing directly — it is raw fish, it is the national dish, and the lime it sits in is doing chemistry rather than seasoning: the acid denatures the surface proteins in minutes, which is why a dish of raw fish behaves less riskily than it sounds. It is entirely reasonable to eat, but eat it at lunchtime in a busy place with high turnover, which is exactly when and where Peruvians eat it, and not from a quiet stall at the end of a hot afternoon.

The Amazon, which is a different health picture

The lowland rainforest is a separate set of considerations from the highlands and needs its own conversation with a travel clinic well before departure. Yellow fever vaccination is the central one and may be checked when travelling to or from Amazon regions; mosquito-borne illness generally is the reason bite avoidance matters here far more than it does in the mountains. What is recommended depends on which gateway you use, how long you stay, where you sleep and on you.

The behavioural part is straightforward and applies regardless of what any clinic advises. Cover arms and legs at dawn and dusk when biting is heaviest, use repellent properly and repeatedly rather than once in the morning, sleep under a net or in a screened room, and take the lodge's guidance on where it is sensible to swim. Lodges here are well practised at all of this and will tell you what applies at their particular stretch of river.

Crime, transport and disruption

The realistic risk in Lima, Cusco and the other cities is opportunistic theft rather than anything more serious, and it concentrates exactly where you would expect: crowded markets, bus terminals, busy plazas, and the moment a phone is out on a café table. The countermeasures are ordinary. Keep valuables out of sight and bags in front of you in crowds. Use ride-hailing apps or taxis arranged by your hotel rather than hailing unmarked cars off the street — street taxis here are unmetered and negotiating in a language you may not speak, at night, in an unfamiliar city, is a poor position. Carry a copy of your passport rather than the original for routine identification.

Long-distance road travel deserves a note of its own. The mountain highways are genuinely demanding — high, winding, and frequently driven overnight — and the established long-distance coach companies with proper safety records are worth choosing over the cheapest available seat. This is one of the few places where paying more for a bus is a safety decision rather than a comfort one.

Finally, plan for disruption. Peru periodically sees demonstrations and road blockades, and while these are rarely aimed at visitors, they can close roads and railways at short notice — including the corridor to Machu Picchu, which is the one that turns a disruption into a lost booking. Check your government's current travel advisory before and during a trip, keep an eye on local news, and build a buffer day into any itinerary that depends on a specific train on a specific date — the planning guide sets out the booking order that makes that buffer possible. Travel insurance that covers cancellation and that explicitly covers trekking at the altitudes you intend to reach is worth reading the wording of rather than assuming.