Ginkgo biloba and acetazolamide prophylaxis for acute mountain sickness: a randomized, placebo-controlled trial.

BACKGROUND Acute mountain sickness (AMS) commonly occurs when unacclimatized individuals ascend to altitudes above 2000 m. Acetazolamide and Ginkgo biloba have both been recommended for AMS prophylaxis; however, there is conflicting evidence regarding the efficacy of Ginkgo biloba use. We performed a randomized, placebo-controlled trial of acetazolamide vs Ginkgo biloba for AMS prophylaxis. METHODS We randomized unacclimatized adults to receive acetazolamide, Ginkgo biloba, or placebo in double-blind fashion and took them to an elevation of 3800 m for 24 hours. We graded AMS symptoms using the Lake Louise Acute Mountain Sickness Scoring System (LLS) and compared the incidence of AMS (defined as LLS score > or =3 and headache). RESULTS Fifty-seven subjects completed the trial (20 received acetazolamide; 17, Ginkgo biloba, and 20, placebo). The LLS scores were significantly different between groups; the median score of the acetazolamide group was significantly lower than that of the placebo group (P=.01; effect size, 2; and 95% confidence interval [CI], 0 to 3), unlike that of the Ginkgo biloba group (P=.89; effect size, 0; and 95% CI, -2 to 2). Acute mountain sickness occurred less frequently in the acetazolamide group than in the placebo group (effect size, 30%; 95% CI, 61% to -15%), and the frequency of occurrence was similar between the Ginkgo biloba group and the placebo group (effect size, -5%; 95% CI, -37% to 28%). CONCLUSIONS In this study, prophylactic acetazolamide therapy decreased the symptoms of AMS and trended toward reducing its incidence. We found no evidence of similar efficacy for Ginkgo biloba.