Altitude sickness can begin in susceptible people at elevations as low as 2400 meters
. The early symptoms are drowsiness, feeling unwell, and weakness, especially during exercise. More severe symptoms are headache, poor sleep, persistent rapid pulse, nausea and sometimes vomiting, especially in children. More severe symptoms include pulmonary edema (fluid in the lungs; persistent coughing), confusion, psychosis, hallucination and death.
Victims can sometimes control mild altitude sickness by consciously taking ten to twelve rapid large breaths every five minutes. If overdone, this can blow off too much carbon dioxide and cause tingling in the extremities of the body. The quickest cure is to reduce the victim's altitude if possible. Some mountain rescue groups carry acetazolamide (a prescription drug) to treat mountain sickness, injectable steroids to reduce pulmonary edema, and inflatable pressure vessels to relieve and evacuate severe mountain-sick persons.
Altitude acclimatization has two stages. Overnight, the body can adjust its carbonic acid balance, and substantially improve its performance. Over four to six weeks, the body can grow more blood cells, strengthen the heart and make other tissue changes. Above 5,500 meters, further altitude exposure weakens, rather than strengthening one's acclimation.
