How many meters above sea level cause altitude sickness?

It is normal to have altitude sickness at high altitudes. It is difficult for most people to adapt to the sudden high altitude, and it will take a few days to get used to it. So how many meters above sea level will there be altitude sickness?

1. Altitude sickness may occur at altitudes above 2,500 meters, while altitude sickness is unlikely to occur at altitudes below 2,500 meters, which is related to individual tolerance, individual differences, and cardiopulmonary function status.

2. Clinically, altitude sickness is all high altitude boundaries. The higher the relative altitude, the less oxygen contained in the atmosphere, and the greater the possibility of patients suffering from high altitude encephalopathy.