The single most effective natural way to prevent altitude sickness is climbing slowly enough to let your body adjust. No supplement, food, or breathing technique comes close to the protection that a gradual ascent provides. Beyond pacing, a handful of other strategies, including staying hydrated, eating well, and managing your iron stores, can meaningfully support your body’s adjustment to thinner air.
What Happens in Your Body at Altitude
Understanding acclimatization helps explain why certain natural strategies work and others don’t. When you ascend, the air contains less oxygen per breath. Your body’s oxygen sensors, located near the carotid arteries in your neck, detect this drop almost immediately and trigger faster, deeper breathing. This hyperventilation is your first line of defense, and it continues to ramp up over several days as those sensors grow increasingly sensitive to low oxygen.
Breathing faster comes with a side effect: you exhale more carbon dioxide than usual, which shifts your blood chemistry toward alkaline. Your kidneys spend the next few days correcting this by flushing out bicarbonate, gradually restoring balance. Meanwhile, your kidneys also release a hormone called erythropoietin (EPO), which tells your bone marrow to produce more red blood cells. This process is slow and takes several weeks to reach full capacity, which is why spending time at moderate altitude before going higher makes such a difference.
Ascend Slowly: The Most Proven Strategy
The Wilderness Medical Society recommends three specific rules for climbing. First, avoid jumping to a sleeping altitude above 2,750 meters (9,000 feet) in a single day. Second, once you’re above 3,000 meters (9,800 feet), increase your sleeping altitude by no more than 500 meters (1,650 feet) per night. Third, build in an extra rest day for every 1,000 meters (3,300 feet) of sleeping altitude gained.
The emphasis on “sleeping altitude” is intentional. You can hike higher during the day as long as you come back down to sleep. This “climb high, sleep low” approach gives your lungs and blood chemistry repeated exposure to thinner air while letting your body recover overnight at a more comfortable elevation. If you’re flying directly into a high-altitude city like Cusco (3,400 meters) or La Paz (3,640 meters), plan to take it very easy for the first one to two days. Avoid strenuous activity and give your breathing rate and kidney function time to catch up.
How to Recognize Early Symptoms
Altitude sickness is diagnosed using a scoring system called the Lake Louise Scale, which tracks four symptoms: headache, dizziness, gastrointestinal distress (nausea, vomiting, or loss of appetite), and fatigue. Each is rated from 0 (none) to 3 (severe), for a maximum score of 12. A score of 3 or higher, with headache present alongside at least one other symptom, qualifies as acute mountain sickness.
Recognizing these symptoms early matters because the best natural treatment is also the simplest: stop ascending. Stay at your current altitude until symptoms resolve, or descend if they worsen. Pushing through a headache and nausea at 3,500 meters is how people end up with dangerous swelling in the brain or lungs at 4,500 meters.
Hydration and Fluid Loss
Your body loses water faster at altitude than you might expect. The dry mountain air and your increased breathing rate both pull moisture from your system with every exhale. Princeton University’s mountaineering guidelines recommend drinking at least 3 to 4 quarts (roughly 3 to 4 liters) of fluid per day at high altitude. That’s significantly more than most people drink at sea level.
Dehydration mimics and worsens altitude sickness symptoms. Headache, fatigue, and nausea can come from fluid loss alone, making it harder to tell whether you’re dealing with altitude sickness or simply not drinking enough. Carry water with you and sip consistently rather than waiting until you’re thirsty. Urine color is a reliable gauge: pale yellow means you’re on track, while dark yellow means you need to drink more. Adding electrolytes to your water helps your body retain fluid rather than just flushing it through.
What to Eat at Altitude
A carbohydrate-rich diet is commonly recommended at altitude because carbohydrates require less oxygen to metabolize than fats or proteins. When every molecule of oxygen counts, giving your body the most efficient fuel source makes a practical difference. Focus on grains, fruits, potatoes, pasta, and rice. Many people lose their appetite at altitude, so eating smaller, more frequent meals can help you maintain calorie intake even when you don’t feel hungry.
Iron deserves special attention. Your body needs adequate iron stores to produce the extra red blood cells that altitude demands. The Wilderness Medical Society suggests checking your ferritin level (a blood marker of iron stores) before a trip. If it’s below 100 ng/mL, supplementing with 200 mg of elemental iron daily starting about a week before your trip and continuing through it can support acclimatization. If your ferritin is between 100 and 130 ng/mL, 100 mg daily is a reasonable dose. Above 130 ng/mL, supplementation probably isn’t necessary. A simple blood test from your doctor can tell you where you stand.
Supplements That Don’t Work
Ginkgo biloba is one of the most commonly marketed natural remedies for altitude sickness, but the clinical evidence is discouraging. A systematic review and meta-analysis published in BMJ Open found that ginkgo biloba had no significant effect in preventing acute mountain sickness compared to placebo. In one well-designed trial, the incidence of altitude sickness was 34% with placebo and 35% with ginkgo biloba, essentially identical. Only one study ever showed a benefit, and it was flagged for high risk of bias.
Beetroot juice, popular for its nitric oxide-boosting properties, is another supplement that sounds promising on paper but fails in practice at altitude. A study published in the Journal of Applied Physiology found that five days of beetroot juice supplementation (containing about 6.4 mmol of nitrate daily) did not reduce altitude sickness or improve exercise performance in hypoxic conditions. In people who were susceptible to altitude sickness, beetroot juice actually made things worse, increasing headache severity, perceived effort during exercise, and blood pressure. The researchers explicitly recommended against using dietary nitrate as a preventive measure for unacclimatized individuals at altitude.
What to Avoid at Altitude
Alcohol is one of the worst things you can consume during the first days at altitude. A study from the German Aerospace Center found that the combination of alcohol and reduced air pressure dropped blood oxygen levels to just over 85% during sleep, well below normal, while pushing resting heart rate up to about 88 beats per minute. These effects occurred in young, healthy subjects. At altitude, where your oxygen levels are already compromised, alcohol amplifies the problem and disrupts the quality of sleep you need for acclimatization.
Sleeping pills and sedatives carry similar risks. They can suppress your breathing rate during sleep, which is the exact opposite of what your body needs to do at altitude. Your respiratory system needs to breathe faster and deeper overnight to compensate for low oxygen. Anything that blunts that response works against acclimatization. Caffeine in moderate amounts is generally fine and may even help with altitude headaches, but avoid it close to bedtime since quality sleep supports recovery.
Pre-Trip Fitness and Preparation
Physical fitness does not prevent altitude sickness. Highly trained athletes get altitude sickness at the same rates as moderately fit people, because the condition is driven by how quickly your blood chemistry and breathing reflexes adapt, not by how strong your cardiovascular system is. That said, being fit means the physical demands of hiking at altitude will be less taxing overall, leaving more of your body’s resources available for acclimatization.
If you have access to moderate altitude before a big trip, spending a few nights at 2,000 to 2,500 meters in the weeks beforehand can give your body a head start. Some people use altitude-simulating tents or masks for pre-acclimatization, though the evidence on their effectiveness is mixed and they’re expensive. The simplest and most reliable preparation remains planning an itinerary that builds in gradual ascent and rest days, rather than relying on any pill, powder, or supplement to do the work for you.