How to Stay Alive Up High

Got a headache? Feel nauseated? You're so irritable your trekking partner has threatened to take the next plane to a different continent? If you've got a problem up high, blame it on the altitude.

That's according to the Himalayan Rescue Association, which educates trekkers on the dangers of altitude sickness (also called acute mountain sickness, or AMS)—and rescues the trekkers who refuse to listen to their advice.

Even in the contiguous United States, where the highest peak is a comparatively paltry 14,494 feet, serious cases of AMS involving cerebral and pulmonary edemas are not uncommon. Sounds sobering? It is. But it's also preventable.

Here's what you need to know:

Why you get it. The air pressure at high elevations is less than that at sea level, so with every breath, you take in less oxygen. The higher you go, the less the air pressure and the greater the problem. You can get used to the lower air pressure—but only if you take the time to acclimatize.

When you'll get it. Unfortunately, there's no hard and fast rule. Different people are susceptible at different elevations—and one person might react differently on two separate occasions. Lots of factors enter into the equation, and scientists don't fully understand them. It's common, however, for fit hikers to feel the effects of altitude at about 10,000 feet. Some people feel the effect of elevation much lower.

Who is at risk? Age, fitness, pre-existing medical conditions, and medications may play a role—but the person who is most at risk is the person who climbs too high too fast. Being super-fit doesn't exempt you. In fact, it may increase your chances of AMS because you're capable of climbing too fast for your own good.

How to avoid AMS:

• If you live at sea level and fly to higher elevations, take a rest day before you start hiking.
• Try to limit your net gain of elevation. There are no hard and fast rules. A commonly accepted limit is a net elevation gain of no more than 1,000 feet a day once you're over 10,000 feet. The Himayan Rescue Association recommends that net elevation gain be limited to 400 meters (about 1,300 feet). If route considerations force you to do more, monitor your condition closely and take a rest day if necessary.
• Medicate. The drug Diamox can be used to help prevent AMS; however, this is something you should discuss with your physician.
• Sleep low: Go ahead and climb during the day—but at night choose campsites at lower elevations so you can recover.
• Drink up. Dehydration contributes to altitude sickness, so keep that canteen handy! Monitor your hydration: Your urine should be almost clear.
• If you feel lousy, assume that it's the altitude: No exceptions, no excuses. The common early symptoms are headaches, slight nausea, dizziness, heart palpitations, and shortness of breath.
• Never go higher if you have even minor symptoms. Wait them out: Usually, they'll go away and it'll be safe to continue.
• If your symptoms worsen or intensify, go downhill to the last place you felt well.
• Severe symptoms can quickly turn into fatal pulmonary or cerebral edemas. If you or your partner have any of the following—staggering and disorientation, vomiting, rapid pulse, cyanosis (bluish coloring of the skin), ragged breathing, and white or bloody sputum—go downhill immediately.