Summary

• Encompasses acute mountain sickness, high-altitude pulmonary oedema, and high-altitude cerebral oedema that occurs in lowland residents following an ascent to altitude.
• Acute mountain sickness is self-limiting and resolves over a number of days at altitude.
• High-altitude pulmonary oedema and cerebral oedema are often fatal if left untreated.
• Descent is the most effective form of treatment for all 3 conditions.
• The diagnosis is usually clinical. However, the combination of a remote environment and the potential for other medical conditions sometimes makes confirmation of the diagnosis difficult to achieve.
• New symptoms at altitude should be assumed to be those of a high-altitude illness until proved otherwise.