At sea level, every litre of air contains a certain amount of oxygen. At 3,000 m it drops by 32%. At 4,000 m — by 40%. At 5,000 m — almost half. The body adapts: makes more red blood cells, increases breathing rate, adjusts blood circulation. This process is acclimatization. Takes 1 to 3 days for normal altitude, up to 2 weeks for extreme.
Peru and Bolivia are high-altitude destinations. Cusco at 3,400 m. Lake Titicaca at 3,812 m. Uyuni at 3,670 m. Passes between cities up to 5,000 m. Ignoring acclimatization = ruining your trip.
What is altitude sickness (soroche)
Acute Mountain Sickness (AMS) — body not getting enough oxygen. Affects 25-50% of people above 3,000 m, especially with rapid ascent.
Symptoms (mild to severe)
- Mild AMS: headache, shortness of breath on exertion, nausea, loss of appetite, insomnia, dizziness
- Moderate: severe headache not relieved by analgesic, vomiting, marked shortness of breath at rest, weakness
- Severe (HACE, HAPE): confusion, ataxia (loss of coordination), foam from mouth, blue lips, coughing up blood. Descend immediately and seek hospital!
Who's at risk
AMS isn't directly related to physical fitness. Often young athletic people get sick first (they ascend faster, drink less).
Higher risk:
- Rapid ascent (flight from sea level direct to Cusco)
- Young age under 50 (older adults are more cautious)
- High physical activity in first days
- Alcohol consumption
- Dehydration
- Prior AMS history
Chronic conditions (cardiovascular, pulmonary) — separate category. Consult a doctor before the trip.
How to acclimatize properly
1. Don't fly directly to Cusco
Direct Lima → Cusco flight (sea level → 3,400 m in 1 hour) is the most common way to get AMS. Better:
- Ideal: Lima → Arequipa (2,335 m, 1-2 days) → Cusco
- Good: Lima → Ica/Nazca (1-2 days in Sacred Valley at 2,800 m) → Cusco
- Minimum: Arrive in Cusco, first 24 hours full rest, no Machu Picchu/trekking
2. Sacred Valley instead of Cusco
The Sacred Valley (Ollantaytambo 2,800 m, Pisac 2,970 m) is lower than Cusco. Spending the first night there makes acclimatization easier.
3. «Climb high, sleep low» rule
Climb higher during the day (e.g., to 4,000 m), come back down to sleep at lower altitude (3,500 m). Body adapts faster.
4. Drink lots of water
At altitude, dehydration happens faster (faster breathing + dry air). 3-4 litres per day is normal. Signal: urine should be light colored.
5. No alcohol the first 2-3 days
Alcohol masks AMS symptoms and dehydrates further. Pisco sours and cocktails — after acclimatization.
6. Don't smoke
Smoking lowers blood oxygen levels. If quitting entirely is impossible — at least for the first 3 days.
7. Light food
Heavy fatty food digests poorly at altitude. First days — light soups, rice, vegetables. No big steaks with wine.
Medications
Acetazolamide (Diamox)
The main drug for prevention and treatment of AMS. Forces kidneys to excrete bicarbonate → blood becomes more «acidic» → body increases breathing faster → better oxygen saturation.
- Prevention dosage: 125-250 mg twice a day, starting a day before ascent, continue 2-3 days at altitude
- Treatment dosage: 250 mg twice a day when symptoms appear
- Side effects: tingling in fingers/toes, changed taste of carbonated drinks (becomes flat), increased urination
- Contraindications: sulfonamide allergy, severe kidney failure
Get a prescription before the trip. Sold without prescription in Peru/Bolivia, but quality varies.
Coca tea
Local traditional remedy. Reduces AMS symptoms — statistically weaker than acetazolamide, but really works. Safe. Served in Cusco cafés and hotels.
Paracetamol / ibuprofen
For headache. Doesn't mask AMS — if pain won't go away, that's a serious symptom, don't suppress it.
Dexamethasone (Decadron)
Only for emergency severe AMS — buys time for descent. Prescription only, not for self-medication.
Route with proper acclimatization
9-day route with gradual altitude gain:
- Day 1-2: Lima (sea level). Arrival, rest, sightseeing
- Day 3: Flight to Cusco. Full rest day in Cusco. No trekking
- Day 4: Cusco → Sacred Valley (Ollantaytambo, 2,800 m, sleep lower than Cusco)
- Day 5: Sacred Valley → Aguas Calientes by train
- Day 6: Machu Picchu (2,430 m, lower than Cusco — easier)
- Day 7: Return to Cusco, acclimatization fully complete
- Day 8-9: Can trek up to 4,500 m, Rainbow Mountain, etc.
In Bolivia:
- Day 10-11: La Paz (3,640 m) — easier after Cusco
- Day 12-13: Salar de Uyuni (3,670 m)
What to bring
- Acetazolamide (get prescription at home)
- Paracetamol / ibuprofen
- Coca tea can be bought locally
- Reusable water bottle
- Electrolytes (powders for water) — against dehydration
- Sunscreen SPF 50+ — UV index higher at altitude
- Warm clothing — nights in Cusco are +5°C even in summer
- Hat, gloves for hikes
Warning signs — when to descend immediately
- Headache doesn't resolve after analgesic for 4-6 hours
- Repeated vomiting
- Shortness of breath at rest (not during exertion)
- Noisy breathing, foamy cough
- Coordination problems (test: walk in a straight line — can't)
- Confusion
Any of these signs = DESCEND 500-1,000 m LOWER, and to hospital. Don't «wait it out». Don't «take ibuprofen». Descent saves lives.
On our tours
In our NOMAP tour to Peru and Bolivia, the team includes a senior paramedic (Ilya). We carry:
- Pulse oximeters (measure oxygen saturation — early AMS detection)
- Oxygen tank in the vehicle
- Emergency med kit
- Contacts at local clinics
Route built with proper acclimatization — Sacred Valley below Cusco in first days, then Machu Picchu, and only then high-altitude activities.
At sea level, every litre of air contains a certain amount of oxygen. At 3,000 m it drops by 32%. At 4,000 m — by 40%. At 5,000 m — almost half. The body adapts: makes more red blood cells, increases breathing rate, adjusts blood circulation. This process is acclimatization. Takes 1 to 3 days for normal altitude, up to 2 weeks for extreme.
Peru and Bolivia are high-altitude destinations. Cusco at 3,400 m. Lake Titicaca at 3,812 m. Uyuni at 3,670 m. Passes between cities up to 5,000 m. Ignoring acclimatization = ruining your trip.
What is altitude sickness (soroche)
Acute Mountain Sickness (AMS) — body not getting enough oxygen. Affects 25-50% of people above 3,000 m, especially with rapid ascent.
Symptoms (mild to severe)
- Mild AMS: headache, shortness of breath on exertion, nausea, loss of appetite, insomnia, dizziness
- Moderate: severe headache not relieved by analgesic, vomiting, marked shortness of breath at rest, weakness
- Severe (HACE, HAPE): confusion, ataxia (loss of coordination), foam from mouth, blue lips, coughing up blood. Descend immediately and seek hospital!
Who's at risk
AMS isn't directly related to physical fitness. Often young athletic people get sick first (they ascend faster, drink less).
Higher risk:
- Rapid ascent (flight from sea level direct to Cusco)
- Young age under 50 (older adults are more cautious)
- High physical activity in first days
- Alcohol consumption
- Dehydration
- Prior AMS history
Chronic conditions (cardiovascular, pulmonary) — separate category. Consult a doctor before the trip.
How to acclimatize properly
1. Don't fly directly to Cusco
Direct Lima → Cusco flight (sea level → 3,400 m in 1 hour) is the most common way to get AMS. Better:
- Ideal: Lima → Arequipa (2,335 m, 1-2 days) → Cusco
- Good: Lima → Ica/Nazca (1-2 days in Sacred Valley at 2,800 m) → Cusco
- Minimum: Arrive in Cusco, first 24 hours full rest, no Machu Picchu/trekking
2. Sacred Valley instead of Cusco
The Sacred Valley (Ollantaytambo 2,800 m, Pisac 2,970 m) is lower than Cusco. Spending the first night there makes acclimatization easier.
3. «Climb high, sleep low» rule
Climb higher during the day (e.g., to 4,000 m), come back down to sleep at lower altitude (3,500 m). Body adapts faster.
4. Drink lots of water
At altitude, dehydration happens faster (faster breathing + dry air). 3-4 litres per day is normal. Signal: urine should be light colored.
5. No alcohol the first 2-3 days
Alcohol masks AMS symptoms and dehydrates further. Pisco sours and cocktails — after acclimatization.
6. Don't smoke
Smoking lowers blood oxygen levels. If quitting entirely is impossible — at least for the first 3 days.
7. Light food
Heavy fatty food digests poorly at altitude. First days — light soups, rice, vegetables. No big steaks with wine.
Medications
Acetazolamide (Diamox)
The main drug for prevention and treatment of AMS. Forces kidneys to excrete bicarbonate → blood becomes more «acidic» → body increases breathing faster → better oxygen saturation.
- Prevention dosage: 125-250 mg twice a day, starting a day before ascent, continue 2-3 days at altitude
- Treatment dosage: 250 mg twice a day when symptoms appear
- Side effects: tingling in fingers/toes, changed taste of carbonated drinks (becomes flat), increased urination
- Contraindications: sulfonamide allergy, severe kidney failure
Get a prescription before the trip. Sold without prescription in Peru/Bolivia, but quality varies.
Coca tea
Local traditional remedy. Reduces AMS symptoms — statistically weaker than acetazolamide, but really works. Safe. Served in Cusco cafés and hotels.
Paracetamol / ibuprofen
For headache. Doesn't mask AMS — if pain won't go away, that's a serious symptom, don't suppress it.
Dexamethasone (Decadron)
Only for emergency severe AMS — buys time for descent. Prescription only, not for self-medication.
Route with proper acclimatization
9-day route with gradual altitude gain:
- Day 1-2: Lima (sea level). Arrival, rest, sightseeing
- Day 3: Flight to Cusco. Full rest day in Cusco. No trekking
- Day 4: Cusco → Sacred Valley (Ollantaytambo, 2,800 m, sleep lower than Cusco)
- Day 5: Sacred Valley → Aguas Calientes by train
- Day 6: Machu Picchu (2,430 m, lower than Cusco — easier)
- Day 7: Return to Cusco, acclimatization fully complete
- Day 8-9: Can trek up to 4,500 m, Rainbow Mountain, etc.
In Bolivia:
- Day 10-11: La Paz (3,640 m) — easier after Cusco
- Day 12-13: Salar de Uyuni (3,670 m)
What to bring
- Acetazolamide (get prescription at home)
- Paracetamol / ibuprofen
- Coca tea can be bought locally
- Reusable water bottle
- Electrolytes (powders for water) — against dehydration
- Sunscreen SPF 50+ — UV index higher at altitude
- Warm clothing — nights in Cusco are +5°C even in summer
- Hat, gloves for hikes
Warning signs — when to descend immediately
- Headache doesn't resolve after analgesic for 4-6 hours
- Repeated vomiting
- Shortness of breath at rest (not during exertion)
- Noisy breathing, foamy cough
- Coordination problems (test: walk in a straight line — can't)
- Confusion
Any of these signs = DESCEND 500-1,000 m LOWER, and to hospital. Don't «wait it out». Don't «take ibuprofen». Descent saves lives.
On our tours
In our NOMAP tour to Peru and Bolivia, the team includes a senior paramedic (Ilya). We carry:
- Pulse oximeters (measure oxygen saturation — early AMS detection)
- Oxygen tank in the vehicle
- Emergency med kit
- Contacts at local clinics
Route built with proper acclimatization — Sacred Valley below Cusco in first days, then Machu Picchu, and only then high-altitude activities.