Altitude sickness is serious and can ruin your trip. The biggest mistake you can make is to fly directly to Cuzco (3326m/10,910ft) and expect to hike the next day. Give yourself a few days to adjust to the altitude first.
Altitude sickness, also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, or Soroche, is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxigen at high altitude. It commonly occurs above 2,400 metres (approximately 8,000 feet). Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE).The causes of altitude sickness are not fully understood. The percentage of oxygen in air remains essentially constant with altitude at 21% up until 70,000 feet (21,330 m), but the air pressure (and therefore the number of oxygen molecules) drops as altitude increases — consequently, the available amount of oxygen to sustain mental and physical alertness decreases above 10,000 feet (3,050m). Altitude sickness usually does not affect persons traveling in aircraft because the cabin altitude in modern passenger aircraft is kept to 8,000 feet (2,440 m) or lower. A superficially related condition is chronic mountain sickness, also known as Monge’s disease, occurring only after prolonged exposure to high altitude. An unrelated condition, often confused with altitude sickness, is dehydration, due to the higher rate of water vapor lost from the lungs at higher altitudes.
Those who ascend rapidly to altitudes greater than 2500m (8100 ft).
May develop altitude sickness. In Peru, this includes Cusco ( 3326m)
Machupicchu (2400m) and Lake Titicaca (3820m). Being physically fitoffers no protection. Those who have experienced altitude sickness in the past are prone to future episodes. The risk increases with faster ascents, higher altitudes and greater exertion.
Symptoms may include headaches, nausea, vomiting, dizziness, malaise, imsomnia and loss of appetite. Severe cases may be complicated by fluids in the lungs (high-altitude pulmonary edema) or swelling of the brain (high-altitude cerebral edema) If symptoms are more than mild or persist for more than 24 hours (far less at high altitudes), descend immediately by at least 500 meters and see a doctor
To help prevent altitude sickness, the best measure is to spend two nights or more at each rise of 1000m. Alternatively, take 125mg or 250mg of acetazolamide (Diamox) twice or three times daily starting 24 hours before ascent and continuing for 48 hours after arrival at altitude. Possible side effects include increased urinary volume, numbness
tingling, nausea, drowsiness, myopia and temporary impotence.
Acetazolamide should not be given to pregnant women or anyone with a history of sulfa allergy. For those who cannot tolerate acetazolamide, the next best option is 4mg of dexamethasone taken four times daily.
Unlike acetazolamide, dexamethasone must be tapered gradually upon arrival at altitude; since there is a risk that altitude sickness will occur as the dosage is reduced
Dexamethasone is a steroid, so it should not be given to diabetics or anyone for whom taking steroids is not adviced. A natural alternative is gingko, which some people find quite helpful.
When traveling to high altitudes, it´s also important to avoid overexertion eat light meals and abstain from alcohol.
Altitude sickness should be taken seriously; it can be life threatening when severe.