Acute Mountain Sickness (AMS) affects up to 50% of trekkers above 3,500 m. Know the symptoms, know the rules, and know when to descend.
Acute Mountain Sickness (AMS) is not a sign of weakness or poor fitness. It is a physiological response to reduced oxygen availability at altitude — and it can affect Olympic athletes just as readily as first-time trekkers. What separates a safe mountain experience from a dangerous one is not whether AMS occurs, but how you recognise and respond to it.
Recognising AMS Symptoms
The Lake Louise Score is the standard assessment tool used by mountain medicine practitioners. A headache plus any one of the following constitutes AMS:
- Headache (especially morning headache that doesn't resolve with paracetamol)
- Loss of appetite or nausea
- Fatigue or weakness disproportionate to effort
- Dizziness or light-headedness
- Difficulty sleeping at altitude
High Altitude Cerebral Oedema (HACE) and High Altitude Pulmonary Oedema (HAPE) are life-threatening progressions of AMS. Signs include: ataxia (inability to walk in a straight line), severe confusion, persistent dry cough, pink frothy sputum, or extreme breathlessness at rest. These require IMMEDIATE descent and emergency evacuation.
The Prevention Protocol
- Ascend gradually — no more than 300–500 m/day above 3,000 m
- Take acclimatisation days seriously — use them for light activity, not rest
- Stay hydrated — 3–4 litres of water daily
- Avoid alcohol and sleeping medication for the first 3 nights at new altitude
- Consider prophylactic Acetazolamide (Diamox) — consult your doctor
- Know the rule: if you feel unwell at altitude, the altitude is the cause until proven otherwise
The One Rule That Saves Lives
Never ascend with symptoms of AMS. This is non-negotiable. Many trekking fatalities are the result of continuing to climb with headache, nausea, or fatigue — hoping symptoms will resolve. They rarely do above the threshold altitude. Descend 300–500 m at the first sign of worsening symptoms.
How Himalvara Manages Altitude Risk
Every Himalvara guide is trained in Wilderness First Aid and altitude medicine. We carry pulse oximeters on every trek above 3,500 m, monitoring blood oxygen saturation daily. Our itineraries are built with contingency descent days, and every expedition carries supplemental oxygen for emergency use.
Our founder's Army training at the High Altitude Warfare School taught him one thing above all else: altitude respect saves lives. We apply the same medical protocols the Indian Army uses for high-altitude operations — because your safety is not something we compromise on.
Mayank Bohra
Mayank Bohra is a Wilderness Emergency Medical Specialist. He designs Himalvara's altitude acclimatisation protocols, briefs every group before departure, and runs on-trek medical response.