It's never a good idea to drive to high altitude, hop out of the car, unfurl your tent and head off for a day of vigorous hiking, skiing or mountaineering. No matter how young and fit you are, how much you've trained at sea level or whether you carb-loaded for breakfast, altitude sickness can strike suddenly, leaving you crippled by headaches, doubled over with nausea and staggering, disoriented by the slightest exertion. To avoid altitude sickness, allow an extra 1-3 days to acclimatize your body to the elevation. If you are planning to ascend above 10,000 feet (3,048 meters), take the extra precaution of starting your trek below 10,000 feet and hiking up -- never ascending more than 1,000 feet (305 meters) per day.
The effects of acute mountain sickness (AMS) include headache, dizziness, fatigue, nauseas and shortness of breath. As AMS progresses, you may also develop mental confusion and a staggering gait. The only cure is to descend, or -- if symptoms are mild enough -- to remain at the same elevation until you acclimatize. "Push through the pain" is never a good mantra at altitude, as AMS can develop quickly into life-threatening conditions such as high altitude pulmonary or cerebral edema. Better mantras are: "Take It Slow" and "Be Prepared."