Travel Health Evidence

Article

Preventing altitude sickness: what the trials support

Updated 4 min read 31 citations

Made-up bed in a three-person internal medicine ward room
玄史生 · CC0 · Wikimedia Commons

Acute mountain sickness shows up as headache, nausea, fatigue and poor sleep within hours of arriving somewhere high — usually above 2,500 metres — and it is common enough on popular routes (Kilimanjaro, Everest Base Camp trekking, high-altitude ski towns) that most travel clinics have a standard conversation about prevention drugs before anyone reaches for antihistamines or coca leaf tea. Several drugs have been tested for prevention, and they are not interchangeable.

Acetazolamide is the most studied option

Acetazolamide has the deepest evidence trail of anything on this list. A 2012 systematic review and meta-analysis [8] and an earlier 2001-era Cochrane-adjacent line of research [5] both examined the drug specifically. It works by forcing a metabolic acidosis that mimics part of the body's natural acclimatization response, and it has the longest track record of the drugs travel clinics prescribe for this purpose. A 2020 comparative study [3] put it head-to-head against ibuprofen — a comparison that matters because ibuprofen is far more accessible over the counter than a prescription carbonic anhydrase inhibitor.

Dexamethasone is the other prescription option with meta-analytic support. A 2014 systematic review and meta-analysis [7] evaluated it as a preventive agent, though dexamethasone is a corticosteroid with its own side-effect profile and is more commonly reserved as a treatment or rescue option rather than routine prophylaxis for a scheduled ascent.

The non-prescription options have thinner support

Ginkgo biloba is widely sold in trekking-town pharmacies as a "natural" altitude remedy. A 2018 systematic review and meta-analysis of randomised controlled trials [6] assessed the evidence directly, and it is worth reading before assuming a herbal product is automatically safer or gentler than a prescription drug — herbal does not mean better-evidenced.

Nitrate supplementation (commonly delivered as beetroot juice or nitrate salts in the sports-nutrition world) has a more recent and narrower evidence base. A 2024 systematic review and meta-analysis [2] looked specifically at oxygen saturation as an outcome — a physiological marker, not necessarily the same thing as fewer or milder symptoms, which is the outcome most travellers actually care about.

The most useful single reference: a head-to-head comparison

Rather than reading each drug's evidence in isolation, a 2025 systematic review and Bayesian network meta-analysis [1] compared multiple prevention drugs against each other directly, rather than each only against placebo. Network meta-analyses like this are more useful than a stack of separate placebo-controlled trials because they let you rank options against each other on the same scale — though we do not reproduce its specific ranking and effect sizes here; the finding worth taking away is that a comparative framework exists and is the right place to look before choosing between options, rather than picking whichever drug is best-marketed.

The Wilderness Medical Society's 2024 clinical practice guidelines [31] are the most current specialty-society consensus synthesizing this evidence base into practical recommendations, and are a reasonable starting point for a travel clinic conversation.

A comparison framework

OptionEvidence typeAccessKey caveat
AcetazolamideMultiple systematic reviews / meta-analysesPrescriptionMost-studied option; side effects include tingling and increased urination
DexamethasoneSystematic review and meta-analysisPrescriptionCorticosteroid; often reserved for treatment/rescue rather than routine prevention
IbuprofenHead-to-head trial vs. acetazolamideOver the counterCompared directly to acetazolamide in the 2020 Medwave study above
Ginkgo bilobaSystematic review of RCTsOver the counter / herbal"Natural" is not a proxy for stronger evidence — read the actual review before relying on it
Nitrate (beetroot juice, etc.)Newer meta-analysis, oxygen-saturation outcomeOver the counterOutcome measured is oxygen saturation, not directly symptom reduction

None of this replaces an individualized conversation with a travel medicine clinician about ascent profile, personal risk factors, and other medications — the table above is a map of what's been studied, not a prescription.

Common questions

Is acetazolamide the best option for preventing altitude sickness?
It has the most extensive evidence base of the options reviewed above, per the 2012 systematic review and meta-analysis, but "most studied" and "best for you personally" aren't automatically the same thing — a clinician should weigh side effects and contraindications.
Does ginkgo biloba actually prevent altitude sickness?
A 2018 systematic review and meta-analysis of randomised controlled trials examined this specifically; check that source directly rather than assuming a herbal supplement carries herbal-grade risk with prescription-grade benefit.
Is ibuprofen a reasonable substitute for acetazolamide?
A 2020 study compared the two head-to-head. It's a fair question to bring to a travel clinic rather than deciding unilaterally, since the two drugs work through different mechanisms.
Does dexamethasone work for prevention, or just treatment?
The 2014 meta-analysis evaluated it for prevention specifically, though it's more commonly used as a rescue/treatment drug in clinical practice due to its steroid side-effect profile.
Does beetroot juice or a nitrate supplement help at altitude?
A 2024 meta-analysis found an effect on oxygen saturation specifically. Whether that translates into fewer felt symptoms of acute mountain sickness is a separate question the oxygen-saturation outcome doesn't directly answer. This article is for informational purposes and is not medical advice; talk to a travel medicine clinician about your own itinerary and health history before an ascent.
Analytical chemistry bench fitted with glassware for titration and pH measurement
Jean-Pierre from Cosne-Cours-sur-Loire (Nièvre, Burgundy… · CC BY-SA 2.0 · Wikimedia Commons
The evidence behind this page A stacked bar showing the composition of the 31 publications cited on this page by study type. 9174meta-analysis (9)randomised trial (17)review (4)other (1)
31 publications, 1970–2026. That is a mix with both trials and syntheses in it, which is the position from which a claim about cause is reasonable. Source: this page’s own citation list, below.

References

Every citation below links to the original peer-reviewed record on PubMed or via DOI. Nothing here is a substitute for medical advice.

  1. Comparative effects of pharmacological interventions for the prevention of acute mountain sickness: A systematic review and Bayesian network meta-analysis Wang J, Lian N, Tang K, et al. · Travel medicine and infectious disease · 2025 · Meta-analysis DOIPubMed 40383249
  2. Effect of nitrate supplementation on oxygen saturation levels for acute mountain sickness prevention: A systematic review and meta-analysis Nafi'an MRT, Sabirin RM, Wibowo RA, et al. · Nitric oxide : biology and chemistry · 2024 · Meta-analysis DOIPubMed 39002891
  3. Ibuprofen versus acetazolamide for prevention of acute mountain sickness Schilling M, Irarrázaval S · Medwave · 2020 · Meta-analysis DOIPubMed 32604398
  4. Wilderness Medical Society Clinical Practice Guidelines for Diabetes Management VanBaak KD, Nally LM, Finigan RT, et al. · Wilderness & environmental medicine · 2019 · Clinical guideline DOIPubMed 31753543Full text
  5. Acetazolamide for the treatment of acute mountain sickness Tapia L, Irarrázaval S · Medwave · 2019 · Meta-analysis DOIPubMed 31891352
  6. Ginkgo biloba extract for prevention of acute mountain sickness: a systematic review and meta-analysis of randomised controlled trials Tsai TY, Wang SH, Lee YK, et al. · BMJ open · 2018 · Meta-analysis DOIPubMed 30121603Full text
  7. Dexamethasone for the prevention of acute mountain sickness: systematic review and meta-analysis Tang E, Chen Y, Luo Y · International journal of cardiology · 2014 · Meta-analysis DOIPubMed 24679688
  8. Acetazolamide for the prevention of acute mountain sickness--a systematic review and meta-analysis Ritchie ND, Baggott AV, Andrew Todd WT · Journal of travel medicine · 2012 · Meta-analysis DOIPubMed 22943270
  9. Altitude sickness Murdoch D · BMJ clinical evidence · 2010 · Systematic review PubMed 21718562Full text
  10. Quercetin prophylaxis in prevention of acute mountain sickness (AMS): a randomized, double blind, placebo controlled phase-II clinical trials Sagi SSK, Kirar V, Prasad J, et al. · European journal of nutrition · 2026 · Randomised controlled trial DOIPubMed 42435069
  11. Efficacy and Safety of Extended-Release Acetazolamide Capsules for the Prevention of Acute Mountain Sickness: A Randomized, Double-Blind, Placebo-Controlled Phase III Trial Danzeng Z, Zhang R, Gesang L, et al. · High altitude medicine & biology · 2026 · Randomised controlled trial DOIPubMed 40955751
  12. Gut microbiota-targeted dietary supplementation with fermentable fibers and polyphenols prevents hypobaric hypoxia-induced increases in intestinal permeability Karl JP, Fagnant HS, Radcliffe PN, et al. · American journal of physiology. Regulatory, integrative and comparative physiology · 2025 · Randomised controlled trial DOIPubMed 40701649
  13. Effects of acetazolamide combined with remote ischemic preconditioning on risk of acute mountain sickness: a randomized clinical trial Liu M, Jiao X, Li R, et al. · BMC medicine · 2024 · Randomised controlled trial DOIPubMed 38166913Full text
  14. Acetazolamide to Prevent Adverse Altitude Effects in COPD and Healthy Adults Furian M, Mademilov M, Buergin A, et al. · NEJM evidence · 2022 · Randomised controlled trial DOIPubMed 38296630
  15. Effects of acetazolamide on pulmonary artery pressure and prevention of high-altitude pulmonary edema after rapid active ascent to 4,559 m Berger MM, Sareban M, Schiefer LM, et al. · Journal of applied physiology (Bethesda, Md. : 1985) · 2022 · Randomised controlled trial DOIPubMed 35511718
  16. Prospective Double-Blinded Randomized Field-Based Clinical Trial of Metoclopramide and Ibuprofen for the Treatment of High Altitude Headache and Acute Mountain Sickness Irons HR, Salas RN, Bhai SF, et al. · Wilderness & environmental medicine · 2020 · Randomised controlled trial DOIPubMed 32057631
  17. Influence of methazolamide on the human control of breathing: A comparison to acetazolamide Teppema LJ, Boulet LM, Hackett HK, et al. · Experimental physiology · 2020 · Randomised controlled trial DOIPubMed 31595565
  18. Acetazolamide does not alter endurance exercise performance at 3,500-m altitude Bradbury KE, Yurkevicius BR, Mitchell KM, et al. · Journal of applied physiology (Bethesda, Md. : 1985) · 2020 · Randomised controlled trial DOIPubMed 31804890
  19. Altitude Sickness Prevention with Ibuprofen Relative to Acetazolamide Burns P, Lipman GS, Warner K, et al. · The American journal of medicine · 2019 · Randomised controlled trial DOIPubMed 30419226
  20. Budesonide Versus Acetazolamide for Prevention of Acute Mountain Sickness Lipman GS, Pomeranz D, Burns P, et al. · The American journal of medicine · 2018 · Randomised controlled trial DOIPubMed 28668540
  21. L-arginine supplementation enhances exhaled NO, breath condensate VEGF, and headache at 4,342 m Mansoor JK, Morrissey BM, Walby WF, et al. · High altitude medicine & biology · 2005 · Randomised controlled trial DOIPubMed 16351563
  22. Acetazolamide reduces exercise capacity and increases leg fatigue under hypoxic conditions Garske LA, Brown MG, Morrison SC · Journal of applied physiology (Bethesda, Md. : 1985) · 2003 · Randomised controlled trial DOIPubMed 12391068
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