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Original Investigation
February 14, 2005

Ginkgo biloba and Acetazolamide Prophylaxis for Acute Mountain Sickness: A Randomized, Placebo-Controlled Trial

Author Affiliations

Author Affiliations: Departments of Emergency Medicine (Drs Chow, Browne, Heileson, and Green) and Pharmacy (Dr Wallace), and Loma Linda University Medical Center and Children’s Hospital, and the Department of Medicine, Loma Linda University and the Jerry L. Pettis Memorial Veterans Affairs Medical Center (Dr Anholm), Loma Linda, Calif. Dr Browne is now with the Department of Emergency Medicine, University of Colorado Health Sciences Center, Denver, and Dr Heileson is with the Department of Emergency Medicine, Rose Medical Center, Denver.

Arch Intern Med. 2005;165(3):296-301. doi:10.1001/archinte.165.3.296

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 ≥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.