Why trust this guide?
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 Langtang Valley library →Acute mountain sickness can begin after ascent and commonly includes headache with symptoms such as nausea, dizziness, unusual tiredness or poor sleep. Treat a change in health as a decision point, not an inconvenience.
What this means
AMS is a pattern of symptoms after recent ascent; a guide or clinician should consider other causes such as dehydration, infection, exhaustion, migraine or medication effects.
What to do on the trail
- Headache after ascent, especially with nausea or dizziness
- Unusual fatigue, reduced appetite or disturbed sleep
- Poor balance, confusion, breathlessness at rest or a wet cough are red flags for more serious illness
- Never use a normal-looking pulse-oximeter reading to dismiss a worsening clinical picture
Do not ascend with worsening symptoms. Stop, tell the guide, rest at the same altitude or descend according to professional advice.
Build it into the itinerary
Share the plan with every trek member before departure. Agree who makes the decision to stop or descend, where the nearest help is expected and how the operator and insurer will be contacted.
Current weather, transport, local medical access and trail conditions can change. Reconfirm the operational plan in Kathmandu and again with the guide before the high stages.
Useful answers
Frequently asked questions
Can I continue if I have a mild headache?
Do not decide from headache alone. Stop ascending, report it, check for other symptoms and follow the guide or clinician's assessment. Symptoms that worsen require descent and professional help.
Is AMS the same as dehydration?
No. Dehydration, exhaustion and other illnesses can look similar. A health professional should assess the overall pattern rather than relying on one symptom.
Sources and fact-checking
Rules, prices, access, weather and local procedures can change. Reconfirm current conditions before travel.
Keep planning internally
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