Altitude Sickness Explained

At high altitude, each breath provides less available oxygen than at sea level. The body needs time to adjust, and symptoms can begin after travelling upward, especially when ascent is rapid. Headache is common, with nausea, poor appetite, unusual tiredness, dizziness, and disturbed sleep also possible. Mild symptoms should not be dismissed if they worsen. Severe altitude illness can affect the brain or lungs, causing confusion, poor coordination, breathlessness at rest, a cough, or frothy sputum. Fitness does not guarantee protection, and a previous comfortable trip does not predict every future response.

Stop ascending when symptoms appear and rest at the same elevation while monitoring closely. Avoid alcohol and strenuous exertion, and drink normally rather than forcing excessive fluids. If symptoms do not improve or become worse, descend to a lower altitude with assistance. People planning travel to high areas should discuss acclimatisation, medicines, existing heart or lung conditions, and an emergency plan during a travel health consultation. Do not continue upward to reach a planned destination while unwell.

Seek emergency help and descend urgently for confusion, unusual sleepiness, trouble walking straight, fainting, breathlessness at rest, chest tightness, a worsening cough, blue lips, or frothy sputum. Someone with severe symptoms should not descend alone. Persistent headache, repeated vomiting, or worsening nausea also warrants medical advice, especially when rest at the same altitude has not helped.

How should I plan ascent and rest days? Do my medical conditions or medicines change my risk? What symptoms mean I must descend, and what emergency supplies or support should my group arrange?