Altitude sickness is a potentially life-threatening condition that can happen when you're high up on a mountain. It's caused by climbing up too quickly.
The decrease in atmospheric pressure makes breathing difficult, because you are not able to take in as much oxygen. You may also experience:
- headache
- nausea
- dizziness
- exhaustion
In severe cases, altitude sickness can cause fluid to build up either on the lungs or on the brain. These are very serious conditions and require immediate medical attention.
See Altitude sickness - symptoms and complications for more information.
When you may be at risk
Altitude sickness is fairly common among those who spend time at high altitudes, such as mountaineers and skiers.
In its mildest form, altitude sickness can occur at heights over about 2,500m (8,000 feet) above sea level, which is a common height for many ski resorts. However, the more severe symptoms of altitude sickness tend to occur at altitudes of 3,600m (about 12,000 feet) and above.
It is not possible to get altitude sickness in the UK because the highest mountain, Ben Nevis in Scotland, is only 1,344m (4,406 feet) high.
There are no specific factors, such as age, sex or physical condition, that increase a person’s likelihood of getting altitude sickness. Certain people are affected while others are less susceptible to it.
Preventing altitude sickness
Proper acclimatisation is the best way to prevent altitude sickness. Ascending slowly will give your body time to adapt to the change in altitude.
For example, once you are above 3,000m (10,000 feet), try not to increase the altitude at which you sleep by more than 300m a night.
See Altitude sickness - prevention for more advice.
What to do if you get ill
If you have mild symptoms of altitude sickness, continue to ascend but do so gradually and at a steady rate.
If your symptoms are more severe, stay at your current altitude to let your body adjust. If your symptoms do not get better (or they get worse), descend to a lower altitude. See Altitude sickness - prevention for more advice.
