6 Ways to Prevent Altitude Sickness

Around the world, high-altitude adventures await. From Patagonia to Mount Kilimanjaro, the Alps to the Rockies, and Denali to the Himalayas, many mountainous areas offer stunning natural landscapes, immersive cultural experiences, and crisp air. As diverse as these regions are, though, they have one thing in common: substantially less oxygen in the air compared to locations at sea level, due to a significant decrease in atmospheric pressure.

This means that for every breath you take at high elevation, you get substantially less oxygen in your lungs. Particularly for people who live at or near sea level, traveling to high altitude (defined as a place at 8,000 feet above sea level or more) is not without health risks, including nausea, headache, and insomnia.

“Altitude is two things,” says Alan Arnette, a mountaineer, climbing coach, and author of a popular blog among trekkers. “It’s exponential and it’s random. Exponential means that when you go from 10,000 feet to 12,000 feet, that’s one thing, but when you go from 16,000 to 18,000 feet, that’s a whole other world. Random means that altitude can strike anyone at any time.” In other words, even taking precautions is no guarantee that you will be in the clear.

Even though it’s impossible to make travel to elevation free of risk, you can minimize the chances of altitude sickness to help you enjoy your time in the mountains. Here are six tips to consider before your next high-altitude adventure.

1. Prepare before you travel

Before heading to the high hills, you can prepare your body for the lower oxygen levels you will experience. First, begin drinking more water than usual—the High Altitude Doctor recommends between one and one-and-a-half liters of extra water per day, starting a week before traveling.

Second, if you are going to be hiking, practice walking long distances. To prepare for a long-distance trek, Arnette suggests walking at least two hours a day for several weeks, “hopefully on uneven terrain, to work all the micro-ligaments and micro-joints. You don’t need to go to the gym and sweat all over the place. It’s really about building the cardiovascular system and having strong legs and a strong core.”

Third, research the trip you’re about to embark on. If you are doing physical activity, do you know how long each day will last and what kind of terrain you will cover? That will help you better prepare yourself, both physically and mentally.

Last, if possible, talk to your doctor before your trip. The medication Diamox might be a good prophylactic to consider, depending on your medical history (for instance, it is not recommended for people who are pregnant or for those with a history of kidney or liver disease). According to the High Altitude Doctor, when a person takes Diamox 24 hours prior to a high-altitude location and for two days afterward, it can be 75 percent effective in preventing acute mountain sickness (AMS).

Photo by Michelle Heimerman

2. Ascend slowly

The U.S. Centers for Disease Control and Prevention recommends avoiding travel from a low elevation to one above 9,000 feet above sea level in a day. If possible, break during your trip to allow your body to gradually adjust to the lower oxygenation levels. Above 9,000 feet, ascend slowly: Try to increase no more than 1,600 feet per day, particularly if you’re sleeping at high altitudes.

While preparing for my trip to Nepal’s Everest region earlier this year, I heard one adage over and again: “Climb high, sleep low.” This essentially means doing day trips to higher altitudes, which allow you to be exposed briefly to lower oxygen levels, followed by returning downhill and re-oxygenating overnight. Once we crossed 11,000 feet, we spent two nights at every location we visited, which allowed for an acclimatization hike on the days in between. The following morning, we were ready to head uphill and sleep comfortably at a higher altitude.

3. Hydrate, eat, and sleep well

Avoiding AMS, says Arnette, amounts to practicing basic self-care. Above 10,000 feet, he recommends drinking four to six liters of water a day with electrolytes. “You’re still sweating even if you’re at altitude and it’s cold,” he says. “Replenishing sugars and salt is important.”

Likewise, our bodies burn more calories at higher altitudes, meaning that we need to eat foods rich in carbohydrates. The CDC also recommends avoiding alcohol above 8,000 feet, particularly for the first two days of a trip.

Finally, try to sleep well, both to help your body acclimatize and also to recover from any physical activity you might have done during the day.

4. Travel with a reputable operator and with insurance

Many high-altitude areas can be visited on your own, but if you are ascending above 10,000 feet (particularly if you are doing a long-distance trek), there is value in working with a reputable tour operator. They may be able to take you on lesser-known paths, introduce you to cultural traditions, and assist with any altitude-related symptoms that arise. Some operators will also carry oxygen canisters with them, depending on the route and the altitudes reached.

For my trip to Everest Base Camp (17,598 feet above sea level), the tour operator required all of us to get high-altitude rescue insurance in advance of traveling (which cost about $600). This gave me access to a helicopter evacuation in case of a serious medical emergency in the mountains. Well-known insurers include Global Rescue, World Nomads, and Garmin SAR. I would recommend talking to them before your trip to understand the exclusions as well as to let them know of any preexisting conditions you may have.

Photos by Michelle Heimerman

5. Partake in natural local remedies

One night during my trek, when my energy levels started to dip, the chef at Mountain Lodges of Nepal recommended I try garlic soup. Visually, it wasn’t the most appetizing—imagine a bowl of stodgy beige liquid—but it tasted rich and soothing. One cup in, the metaphorical weight on my head already started dissipating, and I started feeling noticeably less dizzy. I noticed that most of the Nepali people traveling with my group were drinking the soup most evenings, along with glasses of warm water.

Years before, in the Andes, I recall being given coca tea as a natural prophylactic to ward off any potential altitude issues. Similarly, most Peruvians around me drank this daily.

These natural remedies may not have as many proven scientific benefits as drinking water and avoiding alcohol, but at least in my case, they certainly did not hurt.

6. Listen to your body—and descend if necessary

The telltale signs of altitude illness may include a headache, dizziness, nausea and/or vomiting, insomnia, a loss of appetite, or shortness of breath. Pay attention to your body as you ascend to higher heights. Are you feeling yourself? Do you need to stop and rest?

In my case, the altitude unfortunately did hit me at Everest Base Camp, and I experienced most of the symptoms mentioned above. Luckily, I was able to take a helicopter from there to the village of Lukla, about 8,000 feet closer to sea level. Experts agree that the most effective treatment against AMS is simply to descend. Even a small decrease in elevation can help symptoms dissipate.

If descending is not an option, try to rest, stay hydrated (ideally with electrolytes) and, if possible, hook up to an oxygen machine.