Altitude sickness (AMS) is the main risk on Himalayan treks above 10,000 ft — not bears, not “cold”. This guide explains what actually happens, how to prevent it, and what our guides do on trail when someone feels unwell. Not medical advice — see a doctor if you have heart/lung conditions.
What is AMS?
Acute Mountain Sickness happens when you gain altitude faster than your body can adjust. Lower oxygen at height causes headache, nausea, poor sleep and fatigue. It can progress to HAPE (lungs) or HACE (brain) — rare but serious. Descending is the treatment — not “pushing through” to summit.
At what altitude does it start?
Many people feel mild symptoms above 9,000–10,000 ft. Sleep disturbance at camp is common. On treks like Kedarkantha (12,500 ft summit) or Gaumukh–Tapovan (14,640 ft), most issues appear at camp — not on day 1 in Sankri.
Symptoms — mild vs serious
| Mild (monitor) | Descend now — tell your guide |
|---|---|
| Light headache, tiredness | Headache not relieved by rest + fluids + paracetamol |
| Poor appetite | Vomiting repeatedly |
| Shortness of breath on stairs at home level | Ataxia — walking like drunk, can’t heel-to-toe |
| Cough with pink froth (HAPE sign) | |
| Confusion, extreme drowsiness (HACE sign) |
Prevention that actually works
- Climb high, sleep low — itineraries with acclimatisation days matter (Har Ki Dun, Gaumukh).
- Hydrate — 3–4 litres/day on trek; urine pale yellow.
- No alcohol at altitude — worsens sleep and dehydration.
- Don’t rush — slowest person sets pace on summit day.
- Diamox (acetazolamide) — some trekkers take 125 mg twice daily after consulting a doctor; we don’t prescribe it.
What we do on our batches
- Pulse oximeter checks on high routes (Kedartal, Gaumukh, Kashmir).
- Turn-back rule: if symptoms worsen after rest at camp, we descend — no argument.
- Guides trained to recognise ataxia and coordinate porter assist downhill.
Read our trek safety page for evacuation reality — helicopter is not included in trek price.
Treks by altitude risk (honest)
- Lower risk for first-timers: Dayara Bugyal, Chopta, Triund
- Moderate: Kedarkantha, Har Ki Dun, Brahmatal
- High — prior experience needed: Gaumukh–Tapovan, Kedartal