Most travelers to Peru can avoid altitude sickness by planning their itinerary to gain elevation gradually, spending the first nights at lower elevations, and considering preventive medication. Cusco sits at roughly 11,150 feet (3,400 meters), high enough that up to half of visitors experience some symptoms. The good news: with a few strategic decisions before and during your trip, you can dramatically reduce your risk.
Why Peru’s Altitude Hits So Hard
As elevation increases, air pressure drops, and with it the amount of oxygen in each breath. This condition, called hypobaric hypoxia, means your body is suddenly getting less oxygen than it’s used to. Your heart rate climbs, your breathing quickens, and your blood thickens over time to carry more oxygen per unit of volume. These are normal compensatory responses, and they take days to fully kick in.
The problem for most Peru travelers is speed. You fly from Lima, which is at sea level, and land in Cusco at 10,800 feet in about an hour. Your body has had zero time to adjust. That mismatch between the oxygen your tissues need and the oxygen they’re actually getting is what causes the headache, nausea, fatigue, and dizziness of acute mountain sickness.
Elevations at Major Peruvian Sites
Knowing the numbers helps you plan. Lima sits at sea level. The Sacred Valley towns of Urubamba and Ollantaytambo are around 9,000 feet (2,750 meters). Cusco is at 11,150 feet (3,400 meters). Machu Picchu is lower than most people expect, at roughly 7,970 feet (2,430 meters). The Inca Trail and Salkantay Trek cross passes above 13,000 feet (3,960 meters). And Rainbow Mountain (Vinicunca) tops out at 17,060 feet (5,200 meters), where the oxygen level is roughly half of what you’d breathe at sea level.
Build Your Itinerary Around Gradual Ascent
The single most effective thing you can do is structure your trip so you sleep at progressively higher elevations. Wilderness medicine guidelines recommend limiting your sleeping elevation gain to no more than 500 meters (about 1,600 feet) per day once you’re above 3,000 meters, with a rest day every three to four days.
For a typical Peru trip, this means heading straight from the Cusco airport to the Sacred Valley rather than spending your first night in Cusco itself. The Sacred Valley sits a couple thousand feet lower, giving your body a gentler introduction. From there, you can visit Machu Picchu (lower still), and finish in Cusco, the highest point of the region. Tour operators in Peru routinely build itineraries this way, gradually stepping up in altitude so each night’s sleep is only slightly higher than the last.
If your schedule allows, spending two full nights in the Sacred Valley before heading to Cusco makes a noticeable difference. Even one night helps. The worst approach is landing in Cusco and immediately going sightseeing at full speed.
Preventive Medication
Acetazolamide (sold under the brand name Diamox) is the most studied preventive medication for altitude sickness. It works by changing the acid-base balance in your blood, which stimulates deeper breathing and increases the amount of oxygen your body absorbs. The CDC recommends a prophylactic dose of 125 mg twice a day, starting the day before you ascend and continuing for the first two days at altitude, or longer if you keep climbing.
The medication does have side effects. Tingling in your fingers and toes is common, and it acts as a mild diuretic, so you’ll urinate more frequently. Carbonated drinks may taste flat or metallic. These effects are harmless but worth knowing about. You’ll need a prescription in most countries, so talk to your doctor before your trip.
What About Coca Tea and Sorojchi Pills?
Hotels and restaurants across the Peruvian highlands offer coca leaf tea (mate de coca) to new arrivals. It’s a cultural staple, and locals swear by it. However, a cohort study of travelers arriving in Cusco found that coca leaf tea was not associated with any decreased risk of altitude sickness. Travelers in the study used coca tea twice as often as acetazolamide, but it showed no measurable protective effect. The researchers noted that preparation varies wildly, with no standardization in the amount of leaves used, making it impossible to even compare doses. Enjoy it for the experience, but don’t rely on it as your prevention strategy.
Sorojchi Pills are an over-the-counter remedy sold in pharmacies throughout Peru. They contain a combination of aspirin, caffeine, and salicylamide. They can take the edge off a headache, much like any mild painkiller, but they don’t address the underlying oxygen deficit or speed up acclimatization. Think of them as symptom relief, not prevention.
Hydration, Alcohol, and Pacing
You’ll hear advice to drink lots of water at altitude. Staying well hydrated is sensible, since you lose more moisture through rapid breathing and the dry mountain air, but research on travelers in Cusco found that increasing fluid intake alone had no effect on altitude sickness risk. Drink when you’re thirsty, carry a water bottle, and don’t force excessive amounts.
Alcohol is worth avoiding for your first day or two at elevation. It can worsen dehydration, disrupt your sleep quality, and mimic or mask altitude sickness symptoms, making it harder to tell whether that headache is from the pisco sour or from low oxygen. Once you’ve had a couple of symptom-free days, moderate drinking is fine for most people.
Physical exertion matters more than most travelers realize. Your first day above 10,000 feet is not the time for a long uphill walk or a heavy meal followed by a city tour. Keep activity light, eat smaller meals, and give yourself permission to nap. Your body is doing significant work behind the scenes: increasing your breathing rate, raising your heart rate, and beginning to produce more oxygen-carrying red blood cells.
Recognize the Warning Signs
Mild altitude sickness feels like a bad hangover: headache, nausea, fatigue, poor appetite, and trouble sleeping. These symptoms typically appear six to twelve hours after arrival and resolve within a day or two as your body adjusts. Ibuprofen can help with the headache.
The red flags are symptoms that get worse instead of better, or new symptoms that suggest the condition is progressing. Severe, unrelenting headache, confusion, loss of coordination (trouble walking a straight line), and persistent vomiting all indicate something more serious. Breathlessness at rest or a wet, gurgling cough can signal fluid building up in the lungs. These complications are rare but dangerous, and the treatment is the same in every case: descend immediately. Even dropping 1,000 to 2,000 feet often produces rapid improvement.
A Practical Pre-Trip Checklist
- Route your itinerary low to high. Fly into Cusco, transfer directly to the Sacred Valley, spend one to two nights there, then move up to Cusco.
- Save the highest destinations for last. Rainbow Mountain and high-altitude treks should come after several days of acclimatization, not on day two.
- Ask your doctor about acetazolamide. Start it the day before you fly to Cusco.
- Keep your first day easy. No strenuous activity, no alcohol, lighter meals.
- Carry ibuprofen. It’s effective for altitude headaches and available everywhere in Peru.
- Know your descent options. If symptoms worsen, moving to lower elevation is the most reliable treatment available.
Fitness level, age, and previous high-altitude experience don’t reliably predict who gets altitude sickness. Fit young travelers get it just as often as older ones. The variable that matters most is how fast you ascend and how much time you give your body to catch up.