Acute Mountain Sickness (AMS) can develop at any altitude over 2000 meters. The early symptoms are headache, extreme fatigue, and loss of appetite. Some people become breathless at rest. AMS is the result of fluid accumulating in parts of the body where it does not belong : in the brain, in the lungs, or both. When mild symptoms develop, it is a signal that you must stay at that altitude until symptoms have gone away.
Never ascend with any symptoms of AMS!
Usually within one or two days you will feel well and can continue your trek.
If you are resting at the same altitude and your symptoms are becoming worse, then it is necessary to descend. Worsening symptoms of AMS including increasing tiredness, severe headache, vomiting, and loss of coordination. These are signs of High Altitude Cerebral Edema (or HACE). HACE can lead to unconsciousness and death within 12 hours if progressive symptoms are ignored. Increasing shortness of breath, cough, and tiredness are signs of High Altitude Pulmonary Edema or HAPE. HAPE can also be rapidly fatal if ignored.
A person suffering from AMS may not have clear thinking and may have to be forced to descend. Even if someone is willing to descent they should never be allowed to descend alone. Keep descending until the person shows some sign of improvement, usually after 300-500 meters of descent. Even if the diagnosis is not clear, but might be AMS, you should descend. You can always re-ascend when the person feels better.
It is best to start descending while the person who is ill can still walk. In Nepal, if the person can no longer walk, a yak or horse might be obtained. Porters can often be found to carry a sick person down. Do not wait for a helicopter. If you choose to administer oxygen or medications do not delay the descent to watch for improvement.
In summary, if you are not doing well at altitude, most likely you have some mild symptoms of AMS. Rest at the same altitude until you feel well. If you are getting worse at the same altitude, descend to at least the last point at which you felt well. If you are not sure of the diagnosis, err on the side of being too cautious. Remember sever altitude sickness if entirely preventable if you follow these guidelines.
Are you thinking of going trekking? Find out about the treks that we offer in Nepal & Turkey
Reproduced by permission of the Himalayan Rescue Association