Objective.—To determine the prophylactic effect of Ginkgo biloba (doses 80 mg/12 h, 24 h before high-altitude ascension and with continued treatment) in preventing acute mountain sickness (AMS) at 3696 m in participants without high-altitude experience.

Methods.—Thirty-six participants who reside at sea level were transported to an altitude of 3696 m (Ollagüe). The participants were divided into 3 groups and received G biloba (n = 12) 80 mg/12 h, acetazolamide (n = 12) 250 mg/12 h, or placebo (n = 12) 24 hours before ascending and during their 3-day stay at high altitude. The Lake Louise Questionnaire constituted the primary outcome measurement at sea level and at 3696 m. A Lake Louise Self-Report Score greater than 3 was indicative of AMS. Oxygen saturation, heart rate, and arterial pressure were taken with each evaluation for AMS.

Results.—A significant reduction in AMS was observed in the group that received G biloba (0%, P < .05) comparison with the groups receiving acetazolamide (36%, P < .05) or placebo (54%). No difference was observed in arterial oxygen saturation in the G biloba (92 ± 2) vs the acetazolamide (89 ± 2) groups. However, a marked increased saturation in arterial oxygen was seen in comparison with the placebo group (84 ± 3, P < .05). No statistically significant differences were observed in mean arterial pressure or heart rate.

Conclusions.—This study provides evidence supporting the use of G biloba in the prevention of AMS, demonstrating that 24 hours of pretreatment with G biloba and subsequent maintenance during exposure to high altitude are sufficient to reduce the incidence of AMS in participants with no previous high-altitude experience.