What should you know about airplane altitude sickness?

A pressurised cabin has less available oxygen than sea level, yet symptoms felt only on the aircraft may also come from dehydration, anxiety, motion sickness, prolonged sitting, or an existing heart or lung condition. The travel route after landing matters: going directly to a high mountain area gives the body less time to adjust.

Acute mountain sickness typically presents with headache after recent ascent, together with symptoms such as nausea, dizziness, unusual tiredness, poor sleep, or reduced appetite. The condition can begin after arrival rather than during the flight.

Blocked ears and facial pressure during take-off or landing result from pressure changes across air spaces and are not the same illness. Likewise, a headache on a plane does not by itself establish altitude sickness. People with significant heart, lung, blood, or sleep-related breathing conditions may need individual advice about cabin oxygen and destination altitude before travelling.

If possible, build gradual ascent and an easier first day into a high-altitude itinerary. Avoid pushing higher when a new headache or sickness develops after ascent. Rest at the same altitude, drink according to thirst, eat light meals if nausea allows, and avoid alcohol or strenuous exercise while unwell.

If symptoms fail to improve or become worse, descend to a lower altitude and obtain medical help. Do not depend on pain medicine to hide worsening symptoms while continuing upward. Travellers with previous altitude illness or a fast, unavoidable ascent should discuss prevention and any appropriate prescription medicine with a travel-health clinician before departure.

Confusion, unusual drowsiness, trouble walking in a straight line, breathlessness at rest, a persistent wet cough, or blue-grey lips after ascent can signal severe altitude illness. Descend promptly if it is safe to do so, arrange emergency assistance, and use supplemental oxygen when trained help makes it available.

During a flight, tell cabin crew immediately about chest pain, fainting, severe shortness of breath, new weakness on one side, confusion, or blue-grey discoloration. These signs have causes beyond altitude sickness and need urgent assessment. A person with severe symptoms should not continue to a higher destination merely because the aircraft has landed.

Share the destination, sleeping altitude, speed of ascent, planned exertion, previous reactions to altitude, and relevant medical conditions. Ask whether the schedule allows acclimatisation, what medicine is suitable for you, how it should be used, and where reliable care or descent routes are available along the journey.