#### Summary points
Acute altitude illnesses are potentially serious conditions that can affect otherwise fit individuals who ascend too rapidly to altitude. They include high altitude headache, acute mountain sickness, high altitude cerebral oedema, and high altitude pulmonary oedema. The number of people travelling to altitude for work (soldiers, miners, construction workers, and astronomers) or for recreation (skiing, trekking, mountain biking, and climbing) is rising, and increased media attention towards these activities has also raised the profile of altitude related illness. Typical scenarios in which such illness might occur are a family trek to Everest base camp in Nepal (5360 m), a fund raising climb of Mount Kilimanjaro (5895 m), or a tourist visit to Machu Picchu (2430 m). Awareness of potential altitude related problems is important even for healthcare practitioners working at lower altitude, because patients may ask for advice about the safety of a proposed journey and how to prevent illness at altitude.
#### Sources and selection criteria
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