On climbs of higher peaks, such as Mt. McKinley, these syndromes can be much more severe, leading to many deaths of ill prepared or poorly experienced climbers. There are other related altitude disorders but these will not be discussed at this time. Table 1 presents the symptom complex of each of these. Each may begin in a mild form and advance to more severe symptoms if the appropriate steps are not taken. Mild symptoms begin as a mild headache, decreased appetite, mild nausea, and malaise.
Moderate symptoms are an increasingly severe headache, vomiting, and a reduced urine output.
The onset of symptoms of HAPE will usually occur within the first two to four days of ascent to a higher altitude. Typically they will begin on the second night. If nothing is done, they can progress from mild symptoms to severe symptoms in 12 to 24 hours. Early symptoms may be weakness, fatigue, and feeling winded with minimal exertion. This may progress to rapid or difficult breathing and coughing.