How do I know if I'm getting high-altitude illness?
Some of the first signs of high-altitude illness are headache, lightheadedness, weakness, trouble sleeping and an upset stomach. If you have these symptoms, stop going up or go back down to a lower altitude until your symptoms go away. More severe symptoms include difficulty breathing even while you're resting, coughing, confusion and the inability to walk in a straight line. If you get these symptoms, go to a lower altitude right away and get help from a doctor.
Written by familydoctor.org editorial staff