Gradual ascent remains the single most reliable natural strategy for preventing altitude sickness, but it is far from the only one with evidence behind it. Acute mountain sickness (AMS) affects a significant share of people who travel above about 2,500 meters, and the underlying problem is straightforward: as you climb, air pressure drops and each breath delivers less oxygen. What makes prevention tricky is that no single trick works for everyone, and some popular remedies have shakier science than their reputations suggest. The good news is that a handful of genuinely useful, drug-free approaches can stack the odds in your favor.
Why Altitude Makes You Sick in the First Place
At sea level, the atmosphere pushes oxygen into your lungs efficiently. As altitude increases, barometric pressure falls and the partial pressure of oxygen drops along with it, creating what researchers call hypobaric hypoxia. That oxygen shortfall is the root cause of AMS and its more dangerous cousin, high-altitude cerebral edema.1ScienceDirect (Progress in Cardiovascular Diseases). Acute Mountain Sickness: Pathophysiology, Prevention, and Treatment – Section: The setting Your body can adapt, but it needs time. Blood vessels in the lungs constrict, fluid shifts in ways that cause headaches and nausea, and your brain essentially protests the reduced oxygen supply. Every natural prevention method works by either easing this oxygen deficit, helping your body adapt faster, or avoiding behaviors that make things worse.
Climb Slowly and Stage Your Ascent
The advice you’ll hear most often is to ascend gradually, sleeping no more than about 300 to 500 meters higher each night once you’re above 3,000 meters, and building in a rest day every three or four days. This staged approach has long been considered the gold standard. One field study, however, found that even a slow ascent with a two-day staging period at an intermediate altitude did not eliminate AMS once participants pushed above 4,000 meters.2Frontiers in Public Health. Dynamics in the prevalence and clinical manifestations of acute mountain sickness of different ascent protocols during high altitudes exposure That doesn’t mean gradual climbing is useless. It means it’s not bulletproof, especially at extreme heights. Your body’s acclimatization process doesn’t follow a neat linear schedule, and individual variation is huge. Treat a slow ascent as the foundation of prevention, not a guarantee.
If your itinerary forces a rapid gain in elevation (a flight into a high-altitude city like Cusco or La Paz, for instance), staging becomes impossible. In those situations, the other strategies in this article matter even more.
Pre-Acclimatization With Hypoxic Exposure
If you have weeks to prepare before a trip, sleeping or resting in a hypoxic tent (or mask system that delivers reduced-oxygen air) can give your body a head start. A recent analysis found that the duration of pre-acclimatization exposure accounted for about three-quarters of the variation in AMS risk reduction, with benefits ranging from modest to substantial depending on total hours spent in simulated altitude.3PubMed Central. Time requirements of pre-acclimatization at simulated altitude to prevent acute mountain sickness Even short protocols can help: a week-long regimen of one hour per day at a simulated oxygen fraction roughly equivalent to very high altitude produced a measurable reduction in AMS symptoms, and that protection persisted for at least a week afterward.4PubMed Central. Carry-Over Quality of Pre-acclimatization to Altitude Elicited by Intermittent Hypoxia: A Participant-Blinded, Randomized Controlled Trial on Antedated Acclimatization to Altitude
For casual trekkers, the practical reality is that hypoxic tents are expensive and inconvenient. But for mountaineers planning expeditions to extreme altitudes, the data suggest that longer cumulative exposure (on the order of many dozens of hours at minimum) produces more robust protection.5Journal of Science in Sport and Exercise. Hypoxia Conditioning for High-Altitude Pre-acclimatization If you can only manage a modest protocol, even a few hours of simulated altitude in the days before your trip is better than nothing.
Slow Deep Breathing at Altitude
One of the simplest tools costs nothing and requires no equipment. Deliberate slow, deep breathing at altitude can meaningfully raise your blood oxygen levels in real time. In studies conducted above 4,000 meters, slow breathing exercises increased oxygen saturation from roughly 80% to about 89%, a clinically meaningful jump that occurred through an increase in the volume of each breath without changing how much air moved per minute overall.6PubMed Central. Effects of Slow Deep Breathing at High Altitude on Oxygen Saturation, Pulmonary and Systemic Hemodynamics In plain terms, deep slow breaths pull more oxygen into the lower portions of your lungs where gas exchange is most efficient.
This isn’t a cure. Once you stop the breathing exercises, your saturation drifts back toward its previous level. But as a way to manage symptoms during the acute phase of acclimatization, or during exertion when you’re feeling lightheaded, it’s a real and immediate tool. The technique is simple: breathe in slowly through your nose for about five seconds, then exhale slowly for about five seconds. Keep your breaths deep and steady. Some people find it helpful to set a timer or use a guided rhythm.
Food and Drink Choices That Help
Two dietary factors have at least some scientific backing. First, a high-carbohydrate diet has been shown in older research to lessen AMS symptom severity.7Journal of Wilderness Medicine. Nutritional intake and carbohydrate supplementation at high altitude The proposed mechanism is straightforward: carbohydrates produce more carbon dioxide per unit of oxygen consumed compared with fats, which stimulates breathing and can slightly improve oxygen delivery. In practice, this means favoring pasta, rice, bread, and starchy foods over fatty meals during the first days at altitude. The effect is modest, but it’s a low-risk adjustment that also helps maintain energy when appetite drops at elevation.
Second, staying well hydrated appears to be protective, though the evidence is less definitive than the popular advice might suggest. One study found that fluid intake was associated with lower AMS incidence and severity, and the trend pointed toward aggressive hydration being beneficial, but the sample size was too small to reach statistical significance.8PubMed. Acute mountain sickness: influence of fluid intake Dehydration definitely makes you feel worse at altitude, and the dry air at high elevations increases water loss through breathing and skin. Drinking plenty of water is sensible advice regardless of its specific effect on AMS scores.
Beetroot Juice and Nitric Oxide
Beetroot juice has generated real interest in altitude research because it is rich in dietary nitrate, which the body converts into nitric oxide, a molecule that relaxes blood vessels. At altitude, blood vessels in the lungs tend to constrict in response to low oxygen, and improving vascular function could theoretically ease that constriction. A small but well-designed crossover trial found that beetroot juice supplementation at 3,700 meters restored arterial endothelial function (a measure of how well blood vessels dilate) to levels comparable to those measured at low altitude, while a placebo did not.9Nitric Oxide. Acute dietary nitrate supplementation improves arterial endothelial function at high altitude: A double-blinded randomized controlled cross over study
A broader review noted that few studies have tested nitrate supplementation at real (as opposed to simulated) altitude, but that the existing evidence points to improvements in endothelial function.10PubMed Central. “Beet-ing” the Mountain: A Review of the Physiological and Performance Effects of Dietary Nitrate Supplementation at Simulated and Terrestrial Altitude Whether those vascular improvements translate into fewer headaches and less nausea is still an open question. The research is promising enough that drinking beetroot juice (or eating nitrate-rich foods like spinach and arugula) before and during altitude exposure is a reasonable gamble with no real downside. Just don’t expect miracles.
Ginkgo Biloba Is Not the Answer Most People Think
Ginkgo biloba is one of the most frequently mentioned natural altitude remedies, but the evidence is disappointingly mixed. One small early study found that ginkgo taken three times daily for just one day before rapid ascent significantly reduced the severity of AMS compared with placebo, though it did not quite reach significance for lowering overall AMS incidence.11PubMed. Ginkgo biloba for the prevention of severe acute mountain sickness (AMS) starting one day before rapid ascent That result generated excitement. But a much larger trial comparing ginkgo, the prescription drug acetazolamide, and placebo among Himalayan trekkers found no benefit for ginkgo. AMS incidence was 35% with ginkgo versus 34% with placebo, while acetazolamide cut it to 12%.12PubMed Central. Randomised, double blind, placebo controlled comparison of ginkgo biloba and acetazolamide for prevention of acute mountain sickness among Himalayan trekkers: the prevention of high altitude illness trial (PHAIT)
A meta-analysis pooling data from multiple trials concluded that ginkgo showed a trend toward benefit but the effect was not statistically significant.13PubMed. Ginkgo biloba extract for prevention of acute mountain sickness: a systematic review and meta-analysis of randomised controlled trials The honest takeaway is that ginkgo probably doesn’t work for most people, or at best has a marginal effect that current studies aren’t large enough to detect reliably. If your altitude prevention plan hinges on ginkgo, you need a better plan.
Garlic Has a Lab Problem
Garlic is sometimes recommended in travel forums and traditional medicine contexts for altitude sickness, and there is an interesting animal study behind the claim. In rats, garlic completely blocked the acute constriction of pulmonary blood vessels caused by low oxygen, through both direct relaxation of arterial walls and effects on the vessel lining.14PubMed. Garlic prevents hypoxic pulmonary hypertension in rats That sounds compelling until you look at what happens in humans. A controlled study of garlic supplementation during exercise in hypoxic conditions found no significant differences in oxygen saturation, blood pressure, heart rate, or exercise performance compared with placebo.15PubMed. Effects of garlic consumption on physiological variables and performance during exercise in hypoxia The disconnect between rat physiology and human physiology is a recurring theme in altitude supplement research. Garlic is perfectly healthy to eat, but there is no good reason to believe it will prevent AMS in practice.
Skip the Alcohol
This may be the least glamorous advice but also among the most important. Alcohol and altitude are a bad combination. A study simulating cabin-altitude hypoxia (roughly equivalent to about 2,400 meters, far lower than most trekking destinations) found that when participants drank a moderate amount of alcohol under hypoxic conditions, their blood oxygen saturation during sleep dropped to a median of about 85%, compared with 88% without alcohol in the same low-pressure environment.16PubMed. Effects of moderate alcohol consumption and hypobaric hypoxia: implications for passengers’ sleep, oxygen saturation and heart rate on long-haul flights Heart rate climbed, deep sleep was dramatically reduced, and the total time spent below the clinical hypoxia threshold of 90% oxygen saturation was extended. Scale that effect up to 3,500 or 4,500 meters, and the picture gets worse.
Alcohol also disrupts sleep quality, promotes dehydration, and dulls your ability to notice early AMS symptoms. The cultural temptation to celebrate arriving at base camp or a mountain lodge with a beer is understandable, but your first night or two at a new altitude is exactly when your body most needs good sleep and maximal oxygen delivery. Wait until you’ve acclimatized before drinking.
Being Fit Won’t Protect You
One of the most persistent misconceptions about altitude sickness is that fit people are immune to it. Research comparing mountaineers across a range of fitness levels found that physical work capacity and exercise intensity during ascent were of minor importance for the development of AMS. Correlations between fitness and symptom severity existed but were small, with correlation coefficients in the range of 0.32 to 0.43.17Journal of Wilderness Medicine. Relationship of mountain sickness to physical fitness and exercise intensity during ascent In practice, highly trained athletes get altitude sickness at roughly the same rates as moderately fit recreational hikers. Some evidence even suggests that very fit people may push themselves harder at altitude, ironically increasing their risk.
This doesn’t mean you should skip training before a high-altitude trip. Cardiovascular fitness matters for performance, endurance, and recovery. It just doesn’t confer special protection against the headache-nausea-fatigue triad of AMS. The person who can run a six-minute mile still needs to climb slowly and hydrate aggressively.
Iron Status and Acclimatization
Here’s a factor that gets almost no attention in popular altitude advice but matters a great deal: your iron levels before you go. At altitude, your body ramps up production of red blood cells to carry more oxygen. That process requires iron. Athletes with low ferritin (the storage form of iron) who spent four weeks at altitude did not increase their red cell volume, while those with adequate ferritin stores saw meaningful increases.18PubMed. Iron insufficiency diminishes the erythropoietic response to moderate altitude exposure A separate study showed that oral iron supplementation during altitude exposure significantly boosted hemoglobin mass gains, with higher doses producing larger effects, while unsupplemented athletes saw their ferritin levels drop by about a third.19PLOS ONE. Pre-Altitude Serum Ferritin Levels and Daily Oral Iron Supplement Dose Mediate Iron Parameter and Hemoglobin Mass Responses to Altitude Exposure
For the average trekker, this means it’s worth having your iron levels checked before a high-altitude trip, especially if you’re female, vegetarian, or a regular blood donor, since all of these increase the risk of depleted iron stores. If your ferritin is low, correcting it beforehand could meaningfully improve your body’s ability to adapt. This is a conversation to have with your doctor, since iron supplementation isn’t appropriate for everyone and can cause side effects.
Populations That Need Extra Caution
Young children present a particular challenge at altitude because they cannot clearly describe their symptoms. A toddler with a pounding headache and nausea may just seem fussy and refuse to eat, which delays recognition of AMS. Parents traveling to high-altitude destinations with pre-verbal children need to be especially conservative with ascent rates and vigilant about behavior changes.20Heart & Lung. High-altitude–related disorders—part ii: prevention, special populations, and chronic medical conditions Pregnant women, particularly in their first trimester, are commonly advised to avoid going beyond moderate altitudes because the risk to the fetus from sustained hypoxia is not well characterized.
People with pre-existing heart or lung conditions face compounded risk at altitude, since their baseline oxygen delivery is already compromised. For these groups, the natural strategies described in this article are still useful but should be paired with medical guidance and, in many cases, pharmacological prevention. “Natural” is not always sufficient when the stakes include someone else’s health.
Genetic Differences in Altitude Tolerance
If you’ve ever wondered why some Sherpas seem almost unfazed by elevations that flatten lowlanders, the answer lies in thousands of years of natural selection. Tibetan and Andean populations, descended from colonizers who arrived at high plateaus roughly 25,000 and 11,000 years ago respectively, have evolved distinct physiological adaptations to chronic hypoxia. Tibetans and Andeans achieve the same functional outcome (full-range oxygen metabolism at altitude) through different biological routes, with large quantitative differences in hemoglobin concentration, lung capacity, and blood flow patterns.21PubMed Central. Two routes to functional adaptation: Tibetan and Andean high-altitude natives The genetic underpinnings of these adaptations are now well documented across multiple studies.22Annual Review of Anthropology. Adaptation to High Altitude: Phenotypes and Genotypes
For the rest of us, this means there is genuine biological variation in susceptibility to AMS that no amount of preparation can fully override. Some lowlanders acclimatize quickly and easily; others are prone to AMS every time, regardless of how carefully they ascend. If you’ve gotten sick at altitude before, you’re more likely to get sick again, and planning accordingly is simply smart. The natural strategies that work well for most people may need to be supplemented with medication for those who are consistently vulnerable.
Coca Leaf Tea in the Andes
Travelers to Peru and Bolivia will quickly encounter coca leaf tea (mate de coca) offered at hotels and restaurants as a remedy for altitude discomfort. Andean populations have chewed coca leaves for centuries to enhance physical performance, and experimental evidence suggests the practice produces benefits during prolonged sustained physical activity.23PubMed Central. Does chewing coca leaves influence physiology at high altitude? The active compounds in coca leaves include small amounts of the alkaloid cocaine, but in the concentrations present in tea or chewed leaves, the pharmacological profile is quite different from the concentrated drug. Coca tea is legal in most Andean countries and widely consumed by locals and tourists alike.
Whether coca tea genuinely prevents AMS or mainly provides a mild stimulant and anti-nausea effect is debated. Controlled studies specifically on coca tea and AMS prevention are scarce. It’s culturally significant, widely tolerated, and may offer subjective relief, but treating it as a reliable prevention strategy would be overstating the evidence. Think of it as part of the local acclimatization toolkit rather than a standalone solution. And be aware that coca leaf products can cause a positive result on drug tests, which matters if you’re subject to workplace or athletic testing after your trip.