Love mountains? Our NOLS Wilderness Medicine Institute classes about high-altitude medicine are often the students' favorites, as every class contains at least a few aspiring mountaineers.
Lurking behind every mandatory summit photo, though, can be a heap of pain and adversity. Hypothermia, frostbite, deli belly, blisters, sore muscles, bad weather, falling rocks and ice, sometimes falling people—there's a whole array of potential obstacles aligned against you.
And the higher you climb the thinner the air gets, leaving you vulnerable to altitude illness. You can beat many of the obstacles with guts and persistence, but the only way to beat altitude illness is by being smart. If you try to grit through altitude sickness, you can get into deep trouble. Sometimes you die.
The mild form of altitude illness is called AMS, or acute mountain sickness. It's a headache, plus other symptoms that resemble the flu or maybe a hangover: nausea, fatigue, loss of appetite, difficulty sleeping, etc.
AMS isn't dangerous, but it should signal a clear warning to the climber to stop climbing. AMS means you are ascending faster than you can adapt, and it's time to pause until feeling better. Most AMS sufferers (who stop climbing) feel better in a day. If the symptoms don't improve in 24 hours, you should head down into thicker air.
The serious forms of altitude sickness, the deadly ones, carry the impressive acronyms HACE and HAPE. They stand for high-altitude cerebral edema and high-altitude pulmonary edema—brain swelling and lungs filling with fluid. Not good, either one, and both are treated by a rapid descent to lower elevations until symptoms improve.