Mountain sickness.

Acute mountain sickness (AMS) is a failure to adapt to high altitude. Although some people may be at increased risk, most cases are unpredictable. Much can be done, however, to prevent AMS or limit its severity. Staging ascent, sleeping low, and avoiding overexertion and respiratory depressants are all helpful. For some, drug prophylaxis should be considered. Treatment is based on clinical severity, with descent remaining the primary treatment for severe cases.