Although minor symptoms such as breathlessness may occur at altitudes of 1,500 metres (5,000 ft), AMS commonly occurs above 2,400 metres (8,000 ft). It presents as a collection of nonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover ''. It is hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can ascend to 2,400 metres (8,000 ft) without difficulty.
when do you start to get altitude sickness
above 2,400 metres (8,000 ft)