Amelioration of the symptoms of acute mountain sickness by staging and acetazolamide.

Treatment by 4 d of residence at 1600 m plus the administration of 500 mg acetazolamide b.i.d. for the last 2 d at 1600 m and the first 2 d at 4300 m was compared with no treatment prior to ascent to 4300 m for prophylaxis of acute mountain sickness. The treatment successfully prevented almost all symptoms of acute mountain sickness. It had no effect on the diminished capacity for maximal or prolonged heavy physical work. The treatment produced a relative acidosis and a comparatively greater arterial oxygen tension at 4300 m.