The high-altitude environment exposes travelers to cold, low humidity, increased ultraviolet radiation, and decreased air pressure, all of which can cause problems. The biggest concern, however, is hypoxia. At 10,000 ft (3,000 m), for example, the inspired PO2 is only 69% of sea-level value. The magnitude of hypoxic stress depends on altitude, rate of ascent, and duration of exposure.

Typical high-altitude destinations include Cusco (11,000 ft; 3,300 m), Puno (12,500 ft: 3,810m), and Arequipa (7,693 ft: 2,345m).

Therefore, acclimatizing for a few days at 8,000–9,000 ft before proceeding to a higher altitude is ideal.

Sleeping at high altitude produces the most hypoxemia; day trips to high altitude with return to low altitude are much less stressful on the body; therefore we recommend to flight from Lima to Cusco and immediately transferred to the Sacred Valley of the Inkas located at (9,186 ft – 2,800m) lower than Cusco city.



If you plan to travel to a higher altitude and sleep there, you can get sick if you don’t ascend gradually:

  • Do not go from a low altitude to sleeping at higher than 9,000 feet above sea level in one day. Instead, spend a few days at 8,000–9,000 feet before proceeding to a higher altitude to give your body time to adjust to the low oxygen levels.
  • Once you are above 9,000 feet, increase your sleeping altitude by no more than 1,600 feet per day. For every 3,300 feet you ascend, try to spend a day without ascending further.
  • Do not drink alcohol or do heavy exercise for at least the first 48 hours after you arrive at an altitude above 8,000 feet.
  • Do not eat heavy meals. Drink tea extracted from the leaves of the coca plant instead. Coca tea is common in the Peruvian Andes and helps to reduce the negative effects of altitude sickness and stomach problems.
  • As an alternative, consider taking a day trip to a higher altitude. It’s less risky to take a day trip to a higher altitude and then return to a lower altitude to sleep.

Acclimatization prevents altitude illness, improves sleep, and increases comfort and well-being, although exercise performance will always be reduced compared with low altitude. Increase in ventilation is the most important factor in acute acclimatization; therefore, respiratory depressants must be avoided. Increased red-cell production does not play a role in acute acclimatization.

NOTE: Sometimes your itinerary may not allow gradual ascent. If this is the case, talk to your doctor about prescribing a medicine to prevent altitude illness. You should also be familiar with the symptoms of altitude illness so that you can take steps to prevent it from becoming more severe. Many high-altitude destinations are remote and lack access to medical care, so preventing altitude illness is better than getting sick and needing emergency treatment.

  • Consider using acetazolamide to speed acclimatization, if abrupt ascent is unavoidable.



The symptoms of altitude illness are similar to those of a hangover: headache, feeling tired, lack of appetite, nausea, and vomiting. Children who cannot yet talk may just seem fussy. Mild cases can be treated according to symptoms (such as with painkillers for a headache) and should go away on their own within a few days. Medicines are available to shorten the time it takes to get used to high altitude. However, people with altitude illness should not continue to ascend until they have gotten used to the altitude. Critically, a person whose symptoms are getting worse while resting at the same altitude must descend or risk serious illness or death.

One severe consequence of altitude illness is swelling of the brain (high-altitude cerebral edema – HACE). Symptoms include extreme fatigue, drowsiness, confusion, and loss of coordination. HACE is rare, but it can be fatal. If it develops, the person must immediately descend to a lower altitude.

Swelling of the lungs (high-altitude pulmonary edema – HAPE) is another severe consequence of altitude illness. Symptoms include being out of breath, weakness, and cough. A person with HAPE should also descend and may need oxygen.



Travelers with pre-existing medical conditions should talk with a doctor before traveling to high altitudes:

  • Before their trip, people with heart or lung disease should talk to a doctor who is familiar with high-altitude medicine.
  • People with diabetes can travel safely to high altitudes, but they must be accustomed to exercise and carefully monitor their blood glucose. Diabetic ketoacidosis may be triggered by altitude illness and may be more difficult to treat in those on acetazolamide. Not all glucose meters read accurately at high altitudes.
  • Pregnant women can make brief trips to high altitudes, but they should talk with their doctor because some doctors recommend that pregnant women not sleep at altitudes above (12,000 ft : 3,658 m)



Altitude illness is divided into 3 syndromes: acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE).


It is the most common form of altitude illness, affecting, for example, 25% of all visitors sleeping above 8,000 ft (2,500 m). Symptoms are those of an alcohol hangover: headache is the cardinal symptom, sometimes accompanied by fatigue, loss of appetite, nausea, and occasionally vomiting. Headache onset is usually 2–12 hours after arrival at a higher altitude and often during or after the first night. Preverbal children may develop loss of appetite, irritability, and pallor. AMS generally resolves with 24–48 hours of acclimatization.



It is a severe progression of AMS and is rare; it is most often associated with HAPE. In addition to AMS symptoms, lethargy becomes profound, with drowsiness, confusion, and ataxia on tandem gait test. A person with HACE requires immediate descent; death from HACE can ensue within 24 hours of developing ataxia, if the person fails to descend.



This is where excess fluid develops in the lungs, either in the lung tissue itself or in the space normally used for gas exchange. This means individuals are unable to perform gas exchange properly, and so person cannot get enough oxygen to function normally. It is caused, by poor acclimatization for people who rapidly ascend at more than 14,000 ft (4,270 m).

Initial symptoms are increased breathlessness with exertion, and eventually increased breathlessness at rest, associated with weakness and cough. Treatment of HAPE consists of immediate improvement of oxygenation either by supplemental oxygen, hyperbaric treatment, or by rapid descent.



Acute Mountain Sickness/High-Altitude Cerebral Edema:

The differential diagnosis of AMS/HACE includes dehydration, exhaustion, hypoglycemia, hypothermia, or hyponatremia. Focal neurologic symptoms, or seizures, are rare in HACE and should lead to suspicion of an intracranial lesion or seizure disorder. Patients with AMS can descend ≥300 m, and symptoms will rapidly abate. Alternatively, supplemental oxygen at 2 L per minute will relieve headache quickly and resolve AMS over hours, but it is rarely available. People with AMS can also safely remain at their current altitude and treat symptoms with nonopiate analgesics and antiemetics, such as ondansetron. They may also take acetazolamide, which speeds acclimatization and effectively treats AMS, but is better for prophylaxis than treatment. Dexamethasone is more effective than acetazolamide at rapidly relieving the symptoms of moderate to severe AMS. If symptoms are getting worse while the traveler is resting at the same altitude, he or she must descend.

HACE is an extension of AMS characterized by neurologic findings, particularly ataxia, confusion, or altered mental status. HACE may also occur in the presence of HAPE. People developing HACE in populated areas with access to medical care can be treated at altitude with supplemental oxygen and dexamethasone. In remote areas, descent should be initiated in any person suspected of having HACE. If descent is not feasible because of logistical issues, supplemental oxygen or a portable hyperbaric chamber can be lifesaving.


High-Altitude Pulmonary Edema

Although the progression of decreased exercise tolerance, increased breathlessness, and breathlessness at rest is almost always recognizable as HAPE, the differential diagnosis includes pneumonia, bronchospasm, myocardial infarction, or pulmonary embolism. Descent in this situation is urgent and mandatory, and should be accomplished with as little exertion as is feasible for the patient. If descent is not immediately possible, supplemental oxygen or a portable hyperbaric chamber is critical. Patients with mild HAPE who have access to oxygen (at a hospital or high-altitude medical clinic, for example) may not need to descend to lower elevation and can be treated with oxygen at the current elevation. In the field setting, where resources are limited and there is a lower margin for error, nifedipine can be used as an adjunct to descent, oxygen, or portable hyperbaric therapy. A phosphodiesterase inhibitor may be used if nifedipine is not available, but concurrent use of multiple pulmonary vasodilators is not recommended.



Here, recommendations for the usage and dosing of medications to prevent and treat altitude illness (it is just a suggestion, we always recommend to talk with a doctor before traveling to high altitudes).


Acetazolamide prevents AMS when taken before ascent and can speed recovery if taken after symptoms have developed. The drug works by acidifying the blood, which causes an increase in respiration and arterial oxygenation and thus aids acclimatization. An effective dose that minimizes the common side effects of increased urination and paresthesias of the fingers and toes is 125 mg every 12 hours, beginning the day before ascent and continuing the first 2 days at altitude, or longer if ascent continues. Allergic reactions to acetazolamide are uncommon. As a non-antimicrobial sulfonamide, it does not cross-react with antimicrobial sulfonamides. However, it is best avoided by people with history of anaphylaxis to any sulfa. People with history of severe penicillin allergy have occasionally had allergic reactions to acetazolamide. The pediatric dose is 5 mg/kg/day in divided doses, up to 125 mg twice a day.



Dexamethasone is effective for preventing and treating AMS and HACE, and perhaps HAPE as well. Unlike acetazolamide, if the drug is discontinued at altitude before acclimatization, rebound can occur. Acetazolamide is preferable to prevent AMS while ascending, with dexamethasone reserved for treatment, as an adjunct to descent. The adult dose is 4 mg every 6 hours. An increasing trend is to use dexamethasone for “summit day” on high peaks such as Kilimanjaro and Aconcagua, in order to prevent abrupt altitude illness.



Nifedipine prevents HAPE and ameliorates it as well. For prevention, it is generally reserved for people who are particularly susceptible to the condition. The adult dose for prevention or treatment is 30 mg of extended release every 12 hours, or 20 mg every 8 hours.


Other Medications:

Phosphodiesterase-5 inhibitors can also selectively lower pulmonary artery pressure, with less effect on systemic blood pressure. Tadalafil, 10 mg twice a day, during ascent can prevent HAPE and is being studied for treatment. When taken before ascent, gingko biloba, 100–120 mg twice a day, was shown to reduce AMS in adults in some trials, but it was not effective in others, probably due to variation in ingredients. Ibuprofen 600 mg every 8 hours was recently found to help prevent AMS, although it was not as effective as acetazolamide. However, it is over-the-counter, inexpensive, and well-tolerated.