Acute mountain sickness is the single most common reason a trek in Nepal ends early. It is also largely preventable, and almost none of the prevention is about fitness.
Go up slowly. That is the whole thing.
Above 3,000 m, sleep no more than 500 m higher than the night before, and take a full rest day every 1,000 m. Our itineraries are built this way, which is why an Everest Base Camp trek is fourteen days rather than the nine it could physically be walked in.
Climbing higher during the day and coming back down to sleep is good for you. A rest day does not mean sitting in a lodge — it means a short walk uphill and back.
Drink, and keep eating
Three to four litres a day. Altitude suppresses appetite exactly when your body needs more fuel, so eat even when you do not feel like it. Dal bhat twice a day is not a cliche; it is the right food for the job and the refill is free.
Know the symptoms, and be honest about them
Headache, nausea, dizziness, no appetite, broken sleep. Mild symptoms are common and usually settle with a rest day. What is not normal:
- Breathlessness at rest
- A cough that produces frothy or pink fluid
- Loss of balance, or being unable to walk a straight line
- Confusion, or unusual behaviour a companion notices before you do
Any of those means descend now, at night if necessary. Several hundred metres usually makes the difference. Every guide we send out carries a pulse oximeter and has the authority to turn a client around — that decision is never the client's alone.
The myths
Being young and fit is not protection; fit trekkers often ascend too fast precisely because they can. Alcohol and sleeping tablets both make it worse. Garlic soup is pleasant and does nothing. Diamox works, but talk to your own doctor before you fly, not to a lodge owner at 4,000 m.
