The symptoms of altitude sickness include: 1  A headache, which is usually throbbing. 2  It gets worse during the night and when you wake up. 3  Not feeling like eating. 4  Feeling sick to your stomach.5  You may vomit. 6  Feeling weak and tired.t happens most often when people who are not used to high altitudes go quickly from lower altitudes to 8000 ft (2438 m) or higher. For example, you may get a headache when you drive over a high mountain pass, hike to a high altitude, or arrive at a mountain resort. Mild altitude sickness is common.