Inadequate time to acclimate may lead to Acute Mountain Sickness (AMS) in any traveler accending to 8,000 ft (2,500 meters) or higher. Susceptibility and resistance to altitude illness are genetic traits, and no simple screening tests are available to predict who will experinece the symptoms. Risk is not affected by training or physical fitness. How a traveler has responded to high altitudes in the past is the most reliable guide for pridicting symptoms of acute Mountain Sickness in future trips. Risk is largely influenced by rate of ascent and exertion and can be catogorized by low, moderate and high risk. See full table 2-07 at the CDC web site
Symptoms of Acute Mountain Sickness
To have an idea of the extent of the problem, approximately 25% of all travelers sleeping above 8,000 ft (2,500 meters) in Colorado experience acute mountain sickness. Symptoms are similar to those of an alcohol hangover. Headache is the primary symptom, sometimes accompanied by fatigue, loss of appetite, nausea, and occasionally vomiting. The onset of headache is usually 2-12 hours after arrival at a higher altitude and often is experienced during or after the first night. Symptoms of acute mountain sickness generally resolves with 24-72 hours of acclimatization.
Tips for acclimatization
* One severe and rare 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 also a rare consequence of acute moutain illness. Symptoms include being out of breath, weakness, and cough. A person with HAPE should also descend and may need oxygen.