Altitude sickness is a common condition that can occur when you climb to a high altitude too quickly.
The decrease in atmospheric pressure makes breathing difficult because you aren't able to take in as much oxygen. Most cases are mild, with symptoms that can include:
Inrare cases, altitude sickness can cause fluid to build up either on the lungs or the brain. These are very serious conditions and require immediate medical attention. Symptoms of severe altitude sickness can include:
You can continue to climb if your symptoms improveafter this.
If your symptoms get worse or don't improve after 24 to 48 hours, you shoulddescend by at least 500m.
Severe altitude sickness is a medical emergency. Someone with severe symptoms should immediately descend to a low altitude and seek medical help.
It usually takes a few days for the body to get used to a change in altitude.
Ascending slowly will give your body time to adapt to the change in altitude. For example, once you're above 3,000m (10,000 feet) try not to increase the altitude at which you sleep by more than 300-500m a night. Keeping hydrated is also important,but make sure you avoid alcohol.
However, the more severe symptoms of altitude sickness tend to occur at altitudes of 3,600m (about 12,000 feet) and above.
It's 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 fitness, that increase a person's likelihood of getting altitude sickness. Certain people are affected, while others are less susceptible to it.Just because you haven't had it before doesn't mean you won't develop it on another trip.
Find out what to do if you have symptoms of altitude sickness, who's affected, and how you can prevent it.
Find out about the symptoms of mild and severe altitude sickness, which include headache, dizziness, nausea and vomiting, shortness of breath, and an increased heart rate.
Find out how altitude sickness should be treated, including descending to a lower altitude, oxygen treatment, and different types of medication.
Altitude sickness can cause potentially life-threatening conditions that affect the brain or lungs. Find out what to do if someone has severe symptoms of altitude sickness.
Find out how to prevent altitude sickness, including climbing slowly, particularly at altitudes of 2,500m or above. Ascending gradually will give your body time to adapt.
Jessica Mathur, a GP from London, was surprised when she became ill with altitude sickness during a holiday in Peru.