AMS occurs when the body fails to adapt quickly enough to reduced atmospheric oxygen at altitude. Above 2,500 m the partial pressure of oxygen drops significantly; above 3,500 m — where most EBC trekking occurs — symptoms become common.
No view, no summit and no schedule is worth your life. If symptoms worsen after 24 hours at the same altitude, or if severe symptoms develop (ataxia, altered consciousness, severe breathlessness at rest), immediate descent of at least 500 m is mandatory. Evacuation by helicopter is arranged by your Lekali Journeys guide.
“Altitude does not care how fit you are, how experienced you are, or how badly you want to reach Base Camp. Acclimatise properly or pay the consequences.”
Our EBC itinerary includes two mandatory acclimatisation days — at Namche Bazaar (3,440 m) and Dingboche (4,410 m) — following the 'climb high, sleep low' principle. Never ascend more than 300-500 m per day above 3,000 m.
Acetazolamide (125-250 mg twice daily, starting 24 hours before ascent) accelerates acclimatisation and reduces AMS incidence significantly. Consult your doctor before the trek — it is a prescription medication and contraindicated in sulphonamide allergy.
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