Travel excursions that involve travel at high, or even very high altitude, are becoming
The following is a classification of what is meant by high altitude:
- high altitude – is anywhere above 2400m and below 3658m e.g. Bogota, Quito
- very high altitude – is anywhere above 3658m and below 5500m e.g. La Paz,
Mount Kenya, Mount Kilimanjaro and Everest base camp.
Issues that need consideration prior to travel at high altitude include:
- increased exposure to sun and ultraviolet light and the need to preventing
- the climate can be cold especially at night
- access to medical care may be difficult
- there is a risk of Acute Mountain Sickness (AMS).
Acute Mountain Sickness (AMS)
Atmospheric pressure decreases with altitude. Although the percentage of oxygen in air
remains the same, the barometric pressure reduces and the amount of oxygen that gets
into the lungs through breathing and the amount of oxygen in the blood is reduced. This
is known as hypoxia and it is the body’s’ response to hypoxia that causes acute
Prevention of AMS
AMS is common at high altitude and more than 50% of travellers who go to 3500m or
above will be affected. There is no way to predict who will be affected. The main way to
prevent AMS is through gradual ascent.
There is some evidence that use of a drug called acetazolamide (also known as
Diamox) can reduce the chance of AMS occurring. This is not given to all travellers to
high altitude as a matter of routine, and the decision on whether it should be taken or not
is for the individual and the advising healthcare professional, and not the excursion
organisers. Where appropriate, it can be prescribed by a physician.
Symptoms of AMS
Symptoms of AMS can be mild or severe and are often unpleasant. Common symptoms
- fatigue, flu like symptoms
- irregular breathing during sleep
- loss of appetite nausea and/or vomiting
- swelling of the face, hands and feet
Key Message: If symptoms of AMS arise then ascent must be stopped. If
symptoms do not resolve then a rapid descent is required. If ignored, AMS is a
potentially life-threatening condition.
Treatment of AMS
The key to treatment of AMS is to descend to a lower altitude. Over and above this, the
actual medical treatment of the condition is too complex for the purposes of this
document. If an excursion is planned to an area of high altitude, at least of the team
leaders should have prior experience of travel to high altitude and know what to do if
someone develops symptoms of AMS. In addition, specialist pre-travel health advice
should be sought in advance.
- seek specialist advice if travelling to an area of high or very high altitude
- one of the group leaders should have prior experience of travel to high altitude
- the key to prevention of AMS is gradual ascent
- group members must report symptoms of AMS to the group leader
- if ignored, AMS can rapidly become a potentially life-threatening condition
- rapid descent is the key to treatment of AMS.
For more information visit http://www.fitfortravel.nhs.uk/advice/general-travel-health-advice/altitudeand-travel.aspx