Altitude sickness

As a climber/mountaineer, any illness at altitude (>8000') is considered altitude-related until proven otherwise. The climbers adage of "climb high/sleep low" works - mild exercise at altitude, then go down to sleep is a good way to acclimate. One big misnomer - there is the same amount (%) of oxygen in the air at the top of Everest as there is at sea level - there is just more "space" between those molecules. it is the atmospheric pressure that is less. It is perfectly normal for folks to be able to walk and talk at 12,000', maybe just not at the same time! Diamox is a prescription medication, and not without its own side effects. Best approach remains to acclimatize slowly. headaches are "normal" - difficulty breathing (more than just needing to catch your breath) is not - cure is to descend. And yes, folks with pre-existing breathing issues will be more susceptible. ST