Acetazolamide in prevention of acute mountain sickness.

A controlled comparative between-group study of 48 climbers ascending Kilimanjaro (5895m) was designed as an extension to our previous double-blind cross-over trial on the same peak in 1980, using acetazolamide to decrease the incidence and effects of Acute Mountain Sickness. A group taking acetazolamide 500 mg each morning for one day before reaching 3000m were compared with 3 control groups of Caucasian subjects and lowland and highland Africans. Efficacy was assessed on climbing performance and scores derived from symptoms recorded daily by subjects. Those taking acetazolamide reached higher altitudes and had lower symptom scores than those in control groups. The results support the use of acetazolamide as an effective prophylactic for Acute Mountain Sickness, for most people in a dose of 500 mg in the morning starting one day before ascent above 3000m. The optimal dose of prophylactic acetazolamide is not established, nor is the most appropriate time for medication prior to ascent.