Some of the most ballyhooed experiences in travel involve journeying to lofty heights—from skiing in the Rocky Mountains to hiking in the Andes and trekking up the Himalayas.
But the low levels of oxygen and barometric pressure at increased elevations can cause altitude sickness (aka acute mountain sickness), which feels more like a hangover than a Rocky Mountain high.
The effects can range from a relatively mild shortness of breath to an emergency situation requiring evacuation from the mountain.
According to medical experts, there are precautions you can take before your trip—and steps to follow during your time up where the air is thin—that will minimize your chances of being brought low by high altitudes. Even how you structure your itinerary can play a part.
Causes and Symptoms of Altitude Sickness
The drops in oxygen and pressure that can lead to altitude sickness occur starting at heights of 2,500m (about 8,000 ft.) above sea level, according to the U.K.’s National Health Service. The agency hastens to add, “It’s not possible to get altitude sickness in the UK because the highest mountain, Ben Nevis in Scotland, is only 1,345m [4,400 ft.].”
But altitude sickness can happen at popular Colorado mountain resorts (Breckenridge, for instance, sits at 9,600 feet above sea level), along Peru’s Inca Trail to Machu Picchu (a route that reaches nearly 14,000 feet in elevation at its highest point), and, naturally, on towering peaks such as Tanzania’s more than 19,000-foot-tall Mount Kilimanjaro and Nepal’s Mount Everest, where base camp sits at an elevation of almost 18,000 feet.
You don’t have to be hiking, skiing, or mountain climbing to succumb to altitude sickness, either. Simply visiting elevated places like La Paz, Bolivia, or Lhasa, Tibet (both just shy of 12,000 feet in altitude), can make you feel unwell.
Age and physical fitness level have little to no bearing on whether a person will develop altitude sickness.
Instead, the primary cause of the illness is “going too high too fast,” as the U.S. Centers for Disease Control and Prevention puts it.
The human body needs time to adjust to the low-oxygen situation. Otherwise, you’ll breathe with increasing rapidity and, in a few hours, start to feel the following:
- • headache
- • dizziness
- • fatigue
- • nausea
- • shortness of breath
Symptoms are liable to be worse at night, causing trouble with sleep.
Typically the condition resolves over 1 to 3 days, per the CDC—provided you don’t ascend any higher.
In rare cases, a lack of oxygen can cause serious and even fatal complications affecting the brain and lungs. Warning signs of severe altitude-related problems include confusion or drowsiness (similar to alcohol intoxication) and major chest congestion with a cough. Anybody experiencing those symptoms should seek medical attention as soon as possible.
How to Prevent Altitude Sickness
Since giving your body time to acclimate to the altitude is key, try to tailor your itinerary so that you ascend slowly. If possible, avoid flying or driving straight to a location 9,000 feet or more above your starting point in one day. Instead, stop at an intermediate altitude for a day or so before heading higher.
For example, the Cleveland Clinic advises spending a night in merely mile-high Denver before continuing on to one-and-a-half-mile-high Vail. The CDC, meanwhile, recommends that passengers who fly into the airport at Cusco, Peru, descend to a lower elevation after arriving to spend a night or two before going higher into the Andes.
Past the 8,000-foot-mark, don’t climb higher than 1,600 feet per day, and give yourself a day of rest for every 3,300 feet.
According to the CDC, “Itineraries along some trekking routes in Nepal, particularly Everest base camps, push the limits of many people’s ability to acclimatize.” Given that nearly 1 in 3 trekkers get altitude sickness during Everest ascents, it’s important to make sure your guide follows a safe schedule.
Even if your plans don’t involve summiting the world’s tallest peak, you should avoid strenuous exercise, at least for your first couple days in any high-altitude destination.
What you eat and drink matters, too. On the liquids front, limit alcohol and caffeinated drinks (particularly for the first 48 hours at high elevations) and drink a lot of water—twice as much as usual to counteract the low humidity in high-altitude environments, according to the Cleveland Clinic.
Foodwise, stick to a low-fat, high-carb diet that will provide plenty of calories but not screw up your digestion. Think whole grains, fruits, and starchy vegetables.
If you have a prior history of altitude-related health issues or can’t avoid huge elevation ascents in one day (what, are you tracking a yeti?), talk with your doctor before your trip about prescribing acetazolamide, a medication that can help prevent altitude sickness.
How to Treat Altitude Sickness
In most cases, the symptoms of altitude sickness will resolve when your body has had enough time to adjust to the environment. So if you don’t feel well, stop and rest, and don’t go any higher for at least 24 hours, advises the U.K.’s National Health Service.
Keep hydrating. Take ibuprofen for your headache.
You should feel better within 2 to 3 days. If your symptoms don’t improve or if they get worse, contact a doctor, who may give you supplemental oxygen or medication and may conclude, in the CDC’s rather ominous phrase, “descent is mandatory.”