At the core of altitude medicine, is an understanding of acclimatization. The earliest sign of acute mountain sickness is a headache, while the formal diagnosis of Acute Mountain Sickness requires a headache + 1 or more of the following:
Nausea, vomiting, anorexia
Fatigue or weakness
Dizzy or lightheadedness
When symptoms progress to ataxia or confusion, be very worried about HACS. Although the initial treatment is always descend until symptoms begin to resolve, administration of oxygen and acetazolamide along with dexamethasone 8mg initially followed by 4mg q6hrs may aid in early recovery.