Lake Louise Consensus Definition 
An Individual is at or above 2500 m (~8000 ft) above sea level and
A headache is present and:
An Individual has any one of the following:
GI Symptoms (nausea, vomiting, anorexia)
Sleep symptoms (insomnia, difficulty sleeping)
Dizziness and/or lightheadedness
Ataxia and confusion heralds onset of headache
An Individual is at or above 2500 m (~8000 ft) above sea level and
A headache is present and:
An Individual has any one of the following:
GI Symptoms (nausea, vomiting, anorexia)
Sleep symptoms (insomnia, difficulty sleeping)
Dizziness and/or lightheadedness
GI Symptoms (nausea, vomiting, anorexia)
Sleep symptoms (insomnia, difficulty sleeping)
Dizziness and/or lightheadedness
Symptoms usually develop 1-6hr after arrival at elevation
May be delayed for 1-2d
Especially common after the 1st or 2nd night's sleep
May be delayed for 1-2d
Average duration of symptoms at 10,000ft = 15hr
At higher elevations symptoms may last weeks / more likely to progress to headache
Acute mountain sickness
Dehydration
Decompression sickness
AMS is not improved by fluid administration alone
Chronic mountain sickness
Body hydration does not influence susceptibility to AMS
High altitude cerebral edema
Exhaustion