What should you know about altitude sickness in travellers?

Early altitude illness commonly includes headache, nausea, reduced appetite, dizziness, tiredness or poor sleep after reaching a higher elevation. It can happen to fit travellers and is not prevented simply by being young or physically strong. Symptoms may begin after several hours or during the first night. More dangerous illness can affect the brain or lungs, causing confusion, poor coordination, breathlessness at rest, a persistent cough or frothy sputum. Alcohol and sedating medicines can make judgment and breathing problems harder to recognise.

Ascend gradually, build in rest days when the itinerary allows, and avoid going higher while symptoms are present. Drink normally, eat light meals if nauseated, and avoid alcohol. Tell travel companions how you feel and do not travel alone when unwell. Stop climbing and seek advice from a clinician or trained expedition professional about suitable treatment. If symptoms worsen, descend promptly; descent is the key emergency measure. People with heart or lung disease, pregnancy, sleep-related breathing problems or previous altitude illness should discuss an itinerary and preventive medicine before travel.

Treat confusion, unusual sleepiness, difficulty walking straight, breathlessness while resting, chest tightness, blue lips, or a cough producing frothy sputum as an emergency. Descend with assistance if possible and contact emergency services. Do not leave a severely unwell traveller alone to fetch help. A headache with vomiting or rapidly worsening symptoms also needs prompt assessment, especially if symptoms do not improve after stopping ascent.

Ask how your health conditions affect the route, whether preventive medicine is suitable, what dose instructions apply, and which symptoms mean you must descend. Share your planned elevations, pace of ascent and access to emergency care.