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Most people can over time acclimate to the higher elevations of The Colorado Trail, which range from 5,500 feet to 13,300 feet and average 10,300 feet. A few people cannot, however, including those who may have an underlying medical condition that may or may not have been diagnosed. But that is not common.

Fully acclimatizing can take days, even weeks, but there are a number of steps that Trail users, especially those planning multiday excursions, can take to ease their transition to the elevation change:

  • Stay high. No, we’re not referring to Colorado’s availability of recreational marijuana. We are suggesting that after arriving in the state, and before striking out on the Trail, that you spend a couple of days in a mountain town at 8,000-9,000 feet, an elevation range most helpful to your body as it begins acclimatizing. (An alternative, though not as effective, would be to stay those days in the mile-high Denver area.) Do some easy day hikes or rides to gauge how your body is adjusting to the change.
  • Take it easy as you start the CT. Plan to hike or bike fewer miles a day the first few days than you might otherwise at lower elevations.
  • Ascend slowly. Ascend no more than 1,000-1,500 feet per day as you get going. This is much easier to do when starting in Denver because of the gradual climb to high elevations.
  • Drink more water than you ordinarily might. Because of Colorado’s relatively low humidity, you’ll lose more-than-normal moisture with every breath. Drinking more water helps counteract the effects of dehydration that can make altitude sickness worse.
  • Get adequate rest. At altitude, your body may need more sleep than normal.
  • Consider medication. A prescription drug, Diamox, is available that can help the body acclimatize. Talk to your doctor about whether this might be right for you. Over-the-counter pain relievers such as ibuprofen can offer headache relief.

It is normal to experience a little shortness of breath, slightly faster pulse rate and difficulty sleeping. However, if you experience headaches, fatigue, loss of appetite, nausea or dizziness, you may be experiencing acute altitude sickness. Make sure you’re adequately hydrated and consider holding your elevation or descending to a lower elevation, depending on how severe the symptoms are. Do not proceed higher until symptoms resolve. If you develop lung congestion, become confused, or lose coordination, this is an emergency and you should return to a lower elevation as quickly as possible. Those symptoms can indicate more serious, and possibly fatal, forms of altitude sickness known as HAPE (high-altitude pulmonary edema) and HACE (high-altitude cerebral edema).

Other symptoms of HAPE are shortness of breath, a cough (particularly if accompanied by frothy sputum (mucus) tinged with blood), difficulty walking, and fever. HACE is often accompanied by confusion, loss of consciousness, fever, and a rapid heartbeat.

Most thru- and multiday hikers and bikers elect to go south from Denver, not only as a matter of convenience but because the elevation gain is much more gradual. From Durango, the CT ascends abruptly to more than 12,000 feet in 23 miles, which is not only more challenging physically but shortens the time for acclimatizing.