In the vast majority of cases, acute mountain sickness, high-altitude pulmonary edema (HAPE), and high-altitude cerebral edema (HACE) can be prevented by ascending slowly once above altitudes >2500 m (about 8200 feet). Once above 3000 m (about 9840 feet), the altitude at which one sleeps should not be increased by more than 500 m (about 1600 feet) in 24 hours. In addition, a rest day should be taken every 3-4 days.[29]Luks AM, Auerbach PS, Freer L, et al. Wilderness medical society clinical practice guidelines for the prevention and treatment of acute altitude illness: 2019 update. Wilderness Environ Med. 2019 Dec;30(4s):S3-18.
https://www.wemjournal.org/article/S1080-6032(19)30090-0/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/31248818?tool=bestpractice.com
In those patients who are prone to AMS or intend to ascend quickly, acetazolamide or dexamethasone may be given prophylactically.[37]Basnyat B, Gertsch JH, Holck PS, et al. Acetazolamide 125mg BD is not significantly different from 37mg BD in the prevention of acute mountain sickness: the prophylactic acetazolamide dosage comparison for efficacy (PACE) TRIAL. High Alt Med Biol Spr. 2006 Spring;7(1):17-27.
http://www.ncbi.nlm.nih.gov/pubmed/16544963?tool=bestpractice.com
[38]Dumont L, Mardirosoff C, Tramèr MR. Efficacy and harm of pharmacological prevention of acute mountain sickness: quantitative systematic review. BMJ. Jul 29;321(7256):267-72.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC27441
http://www.ncbi.nlm.nih.gov/pubmed/10915127?tool=bestpractice.com
[39]Williamson J, Oakeshott P, Dallimore J. Altitude sickness and acetazolamide. BMJ. 2018 May 31;361:k2153.
http://www.ncbi.nlm.nih.gov/pubmed/29853484?tool=bestpractice.com
Acetazolamide is preferred, but if a patient is intolerant or allergic, dexamethasone may be given.[29]Luks AM, Auerbach PS, Freer L, et al. Wilderness medical society clinical practice guidelines for the prevention and treatment of acute altitude illness: 2019 update. Wilderness Environ Med. 2019 Dec;30(4s):S3-18.
https://www.wemjournal.org/article/S1080-6032(19)30090-0/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/31248818?tool=bestpractice.com
[40]Donegani E, Paal P, Küpper T, et al. Drug use and misuse in the mountains: a UIAA MedCom consensus guide for medical professionals. High Alt Med Biol. 2016 Sep;17(3):157-84.
http://www.ncbi.nlm.nih.gov/pubmed/27583821?tool=bestpractice.com
[41]Nieto Estrada VH, Molano Franco D, Medina RD, et al. Interventions for preventing high altitude illness: Part 1. Commonly-used classes of drugs. Cochrane Database Syst Rev. 2017 Jun 27;6:CD009761.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD009761.pub2/full
http://www.ncbi.nlm.nih.gov/pubmed/28653390?tool=bestpractice.com
Systematic reviews assessing the effectiveness of less commonly-used prophylactic medications (e.g., selective serotonin receptor agonists, N-methyl-D-aspartate receptor antagonists, endothelin-1 receptor antagonists, anticonvulsants, and spironolactone), and miscellaneous or non-pharmacological interventions (including ginkgo biloba), have been unable to determine efficacy or safety, because of the small number of studies available and their limited quality.[29]Luks AM, Auerbach PS, Freer L, et al. Wilderness medical society clinical practice guidelines for the prevention and treatment of acute altitude illness: 2019 update. Wilderness Environ Med. 2019 Dec;30(4s):S3-18.
https://www.wemjournal.org/article/S1080-6032(19)30090-0/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/31248818?tool=bestpractice.com
[42]Gonzalez Garay A, Molano Franco D, Nieto Estrada VH, et al. Interventions for preventing high altitude illness: Part 2. Less commonly-used drugs. Cochrane Database Syst Rev. 2018 Mar 12;3:CD012983.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD009761.pub2/full
http://www.ncbi.nlm.nih.gov/pubmed/29529715?tool=bestpractice.com
[43]Molano Franco D, Nieto Estrada VH, Gonzalez Garay AG, et al. Interventions for preventing high altitude illness: Part 3. Miscellaneous and non-pharmacological interventions. Cochrane Database Syst Rev. 2019 Apr 23;4:CD013315.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD013315/full
http://www.ncbi.nlm.nih.gov/pubmed/31012483?tool=bestpractice.com
[44]Tsai TY, Wang SH, Lee YK, et al. Ginkgo biloba extract for prevention of acute mountain sickness: a systematic review and meta-analysis of randomised controlled trials. BMJ Open. 2018 Aug 17;8(8):e022005.
https://bmjopen.bmj.com/content/8/8/e022005.long
http://www.ncbi.nlm.nih.gov/pubmed/30121603?tool=bestpractice.com
Nifedipine has been shown to reduce the incidence of HAPE in individuals with a previous history of radiographically documented HAPE.[45]Bärtsch P, Maggiorini M, Ritter M, et al. Prevention of high-altitude pulmonary edema by nifedipine. N Engl J Med. 1991 Oct 31;325(18):1284-9.
http://www.nejm.org/doi/full/10.1056/NEJM199110313251805#t=article
http://www.ncbi.nlm.nih.gov/pubmed/1922223?tool=bestpractice.com
Individuals with existing medical conditions should consult a physician to discuss pretravel planning in order to decrease risk of high-altitude illness. Discussions should cover whether their conditions are stable, whether any dose adjustments are necessary, and whether the destination has available medical resources.[1]Centers for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 4: environmental hazards & risks - high elevation travel & altitude illness. May 2023 [internet publication].
https://wwwnc.cdc.gov/travel/yellowbook/2024/environmental-hazards-risks/high-elevation-travel-and-altitude-illness
[6]Luks AM, Hackett PH. Medical conditions and high-altitude travel. N Engl J Med. 2022 Jan 27;386(4):364-73.
http://www.ncbi.nlm.nih.gov/pubmed/35081281?tool=bestpractice.com