At high altitudes, travellers may develop altitude sickness (also known as acute mountain sickness), which can be fatal in some cases. 3 The risk relates more to the speed of ascent than the altitude reached.4 Most people who ascend rapidly to heights above 2,500 m can experience a period of acclimatisation during which they can have a variety of symptoms including headache, tiredness, insomnia, nausea and vomiting. Anyone can be affected; women, men and children. Altitude sickness is infrequent below 2,500 m.4
Precautions and prevention3,4 The most effective way to avoid acute mountain sickness is gradual acclimatisation and slow ascent.
Avoid direct travel to high altitudes if possible. Break the journey for 2–3 nights at 2,500–3,000 m to help prevent acute mountain sickness. If direct travel to a high altitude cannot be avoided, the traveller should avoid overexertion, large meals, and alcohol after arrival. Instead keep well hydrated and remain and rest for a few days after you arrive at that altitude before ascending to a higher elevation.
Travellers making a rapid ascent to high altitude (>3,000 m) may consider taking prophylactic medication. However, in general prophylactic medications are not recommended for travellers. It is much safer to rely on good planning and gradual ascent rather than medication. (See your doctor.)
Travellers with pre-existing cardiovascular or pulmonary disease or anaemia should seek medical advice before deciding to travel to high altitude.
Pregnant women should seek medical advice prior to deciding to travel to high altitude. 4
N.B: It is now easy to reach many high places rapidly by air-travel without allowing time to acclimatise. Examples of high altitude cities with airports include:
Cuzco, Peru (3,225 m; 10,600 ft)
La Paz, Bolivia (3,658 m; 12,000 ft)
Lhasa, Tibet (3,685 m; 12,090 ft)
(Please read the Disclaimer before using the ABC Guide to Travel Health).