Trekking
High Altitude Sickness Prevention: The Complete Nepal Trekker's Guide
Altitude sickness (AMS) is the top medical risk on Nepal's high-altitude treks. This guide covers prevention, recognition of symptoms, treatment, when to descend, Diamox use, and emergency evacuation.
Acute Mountain Sickness (AMS) affects approximately 25% of trekkers above 3,500m in Nepal. Understanding it is not optional — it is a safety requirement for anyone trekking above Namche Bazaar.
Overview
AMS occurs when you ascend faster than your body can acclimatise. It begins with headache, nausea, and dizziness. Left unmanaged, it can progress to life-threatening High Altitude Pulmonary Oedema (HAPE) or High Altitude Cerebral Oedema (HACE) within hours.
Prevention Rules
The golden rule: Ascend no more than 300–500m of sleeping altitude per day above 3,000m.
Mandatory rest days: One acclimatisation day for every 1,000m gained above 3,000m. For EBC: minimum at Namche (3,440m) and Dingboche (4,410m).
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Hydration: Drink 3–4 litres of water daily — dehydration accelerates AMS symptoms.
Avoid alcohol in the first 3 days at each new altitude.
Recognising Symptoms
| Severity | Symptoms |
|---|---|
| Mild AMS | Headache, fatigue, loss of appetite, mild nausea |
| Moderate AMS | Severe headache, vomiting, dizziness, shortness of breath at rest |
| HAPE | Breathlessness at rest, cough with pink frothy sputum, severe fatigue |
| HACE | Confusion, inability to walk straight, loss of consciousness |
Treatment
Mild AMS: Rest at same altitude, drink water, take ibuprofen for headache. Do not ascend until symptoms resolve.
Moderate AMS: Descend 300–500m immediately. Take Diamox if available. Seek medical advice.
HAPE/HACE: Emergency descent + emergency evacuation. These are life-threatening — do not delay.
Diamox (Acetazolamide)
Diamox speeds acclimatisation by stimulating breathing. Standard dose: 125–250mg twice daily, starting 1–2 days before major altitude gain. Consult your doctor before your trek — it is a prescription medication.
Helicopter Evacuation
Evacuation from EBC costs USD 3,000–5,000 without insurance. Ensure your travel insurance explicitly covers high-altitude trekking evacuation.
FAQ
Does being fit prevent AMS? No — fitness does not protect against altitude sickness. Athletes are just as susceptible as beginners.
Can children get AMS? Yes — children are more susceptible and less able to articulate symptoms. Monitor carefully.
Is Diamox safe? For most people, yes. Common side effect: tingling in fingers and toes. Avoid if allergic to sulfa drugs.
