How to avoid altitude sickness

Physical fitness does not prevent altitude illness. Once you are at elevation, avoid climbing higher while unwell; rest at the same level and descend if symptoms worsen.

Air pressure falls as elevation rises, so each breath delivers less oxygen. The body needs time to adapt. Going up too quickly can bring headache, nausea, dizziness, tiredness, poor appetite or disturbed sleep.

Symptoms often begin after reaching a higher sleeping altitude. They can affect healthy travellers as well as people with medical conditions, and a previous trouble-free trip does not predict every future ascent.

Build flexibility into the itinerary so your sleeping elevation rises slowly and you can pause when needed. Keep exertion gentle during early days, drink according to thirst, eat regular meals and avoid using sleeping medicines unless a clinician familiar with altitude travel says they are suitable.

Before a rapid or very high trip, discuss your route, health conditions and medicines at a travel health consultation. A clinician may consider preventive medicine for some itineraries, but it does not replace gradual ascent or symptom monitoring.

Do not ascend with headache or nausea that is developing at altitude. Descend and seek urgent medical help for confusion, unusual drowsiness, difficulty walking in a straight line, breathlessness at rest, chest tightness, blue or grey lips, or a wet cough.

These signs can reflect serious altitude illness. Oxygen and medical treatment may be needed, but waiting for treatment should never delay descent when it can be performed safely with assistance.

Ask whether your planned sleeping elevations allow enough adjustment, whether any existing heart or lung problem changes the plan, and how your regular medicines behave at altitude. Clarify which symptoms should trigger descent and whether preventive medication is appropriate for your route.