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This article keeps the decision near the top, separates planning guidance from changing conditions and points you back to the complete internal library.
Browse the full Annapurna Base Camp library →Altitude illness can affect any trekker, regardless of age or fitness. The safest approach is gradual ascent, two acclimatization days, good communication and immediate action when symptoms worsen. Never ascend with worsening symptoms.
Common early symptoms
Acute mountain sickness commonly presents as headache together with nausea, dizziness, unusual fatigue, poor appetite or disturbed sleep after gaining altitude. Symptoms should be reported to the guide, not hidden to protect the itinerary.
A mild headache alone may have other causes, including dehydration or sun exposure, but it still deserves monitoring. The important questions are whether symptoms are improving, stable or worsening and whether new signs appear.
Emergency warning signs
- Difficulty walking in a straight line, confusion, unusual behaviour or reduced consciousness.
- Breathlessness at rest, a persistent wet cough, chest tightness or rapidly declining exercise tolerance.
- Severe or worsening headache, repeated vomiting or symptoms that do not improve with rest.
These can indicate life-threatening high-altitude cerebral or pulmonary oedema. Stop ascending, begin descent with assistance and activate professional medical or rescue support.
Practical prevention
- Follow a gradual itinerary and sleep at the planned altitude even if you feel strong.
- Walk at a pace that allows conversation and avoid racing to the next lodge.
- Drink normally, eat enough carbohydrates and avoid excessive alcohol or sedatives.
- Attend daily health checks and report headache, nausea, breathlessness or poor coordination early.
- Discuss preventive medication and personal medical risks with a qualified clinician before travel.
Evacuation and insurance
Descent is the primary response to significant altitude illness. Depending on location and condition, this may be on foot, with assisted transport or by jeep when weather and operations permit.
Buy insurance that explicitly covers trekking to at least 4,500 metres and emergency evacuation. Carry the policy number and emergency contact process, and understand that a jeep is not guaranteed in poor weather.
Useful answers
Frequently asked questions
Does being fit prevent altitude sickness?
No. Fitness helps with walking but does not reliably predict acclimatization. Fit trekkers can become ill, especially if they ascend too quickly.
Should I take Diamox?
Acetazolamide can be useful for some travellers, but it is a prescription medicine with contraindications and side effects. Discuss it with a qualified clinician before travel.
Can oxygen replace descent?
Supplemental oxygen may support emergency care, but it does not make continued ascent safe. A sick trekker still needs professional assessment and usually descent.
Sources and fact-checking
Rules, prices, access, weather and local procedures can change. Reconfirm current conditions before travel.
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