Heading for High Altitudes? 4 Things Travelers Should Know About Altitude Illness

It’s happened to countless travelers on hiking, climbing, and skiing trips. You’ve prepped your gear and your itinerary. You’ve arrived at your destination. You’re ready to get out there and enjoy yourself. But after a few hours (or less), you start feeling tired and irritable, a bit nauseous with a headache.

These symptoms, combined with recent travel, are telltale signs of altitude illness. Altitude illness occurs because of a lack of oxygen at high altitudes, and it affects mountain climbers, recreational hikers, skiers, and others who travel to high altitudes.

Altitude illness should be a consideration for anyone planning a trip to high altitudes (generally above 8,000 feet, but sometimes lower). Here are four things to know about altitude illness.

1. Altitude illness falls into three categories

Generally, there are three conditions related to altitude illness. Acute mountain sickness (AMS) is the mildest and most common of the three. Symptoms usually develop within 6 to 10 hours of ascent (increase in altitude) and often include headache and one or more other symptoms, such as light-headedness, loss of appetite, nausea, vomiting, fatigue, weakness, or irritability.

High-altitude cerebral edema (HACE) is a rare but potentially fatal condition in which the brain swells with fluid. People with HACE have headaches, confusion, and unsteady and uncoordinated walking (ataxia).

The third condition is high-altitude pulmonary edema (HAPE), which causes difficulty breathing and can cause low blood oxygen levels because of fluid build-up in the lungs that usually develops 24 to 96 hours after a rapid ascent to over 8,000 feet. It can occur in people even if they do not have symptoms of AMS.

HACE and HAPE are severe conditions that require immediate attention and treatment that often involves a descent to lower altitudes.

2. Don’t overlook AMS as a cause of symptoms

Many symptoms of AMS are relatively common when traveling. Plenty of people suffer from a headache, irritability, or fatigue after a long flight or car ride. But if you’re at a higher elevation, remember that AMS could be a cause and watch for more serious symptoms. If you don’t feel better with rest, water, and maybe some over-the-counter headache medicine, it may be time to talk to a medical professional and get to a lower elevation.

People say dehydration causes AMS. That’s not true, but it’s easier to become dehydrated at higher altitudes. It’s still a good idea to drink plenty of fluids. Dehydration can also make you feel tired and lightheaded just like AMS, so if you don’t feel better after drinking enough water this might be another time to talk to a medical professional.

3. The altitude always wins

One of the biggest misconceptions about altitude illness is that being in good shape reduces your risk. That’s not true. What’s more, other medical conditions like asthma or high blood pressure (hypertension) don’t make people more likely to suffer from AMS. Everyone’s tolerance is different, and you won’t know how you handle different altitudes until you’re exposed to them.

At the same time, physical exertion at higher altitudes is hard work. Being in good shape won’t prevent altitude illness, but it is still an essential consideration for strenuous trips at higher elevations.

If you’re traveling at heights, remember: The altitude always wins. Altitude doesn’t care how determined you are or how excited you are to ski a particular slope or hike a particular mountain. If you’re having symptoms of altitude illness, you need to stop and potentially get to a lower altitude. Pushing yourself to go higher is a risk.

4. Staying safe starts with smart planning

Everyone wants to make the most of their trips and travel. But ascending too quickly is the primary risk factor for altitude illness. Build time to acclimate to higher altitudes into your trip planning and give yourself and your group time to get used to the new conditions. You may be anxious to start skiing or hiking, but it’s often better to take it easy on that first day and make sure everyone is comfortable at that elevation.

When planning trips with large groups, keep in mind that each person will acclimate differently. Ask people if they’ve traveled to high altitudes before and be conservative in planning activities. And remember — the altitude always wins. If in doubt, go down where there is more oxygen.

To learn more about altitude illness, visit the Manuals page or the Quick Facts on the topic.