The first two or three days above 3,000 metres are uncomfortable for almost everyone. Expect a dull headache, broken sleep, no appetite and breathlessness walking uphill at a pace that would be nothing at home. All of that is ordinary and passes as you acclimatise. What is not ordinary is a headache that will not shift, breathlessness while sitting still, vomiting or unsteadiness on your feet — those mean go down.
The headache
It is usually frontal, dull rather than sharp, and worst in the evening and on waking. It responds to water, rest and ordinary painkillers, and it fades over a couple of days as your body catches up. Most people are mildly dehydrated as well as short of oxygen, because the air is dry, you breathe harder, and nobody drinks enough when it is cold and the toilet is outside.
Being able to tell that headache from the one that matters is the whole skill, and it is set out properly in our guide to altitude sickness and acclimatisation in Nepal. This page is about what the first nights feel like, not what to do about them clinically.
The sleep
Bad, and worse than the headache for most people. You fall asleep, wake after an hour for no reason, and lie there. Dreams are strange and vivid. Many people experience periodic breathing at altitude, where the rhythm gets shallower and shallower, pauses, and then restarts with a gasp that wakes you up. It is a normal response to thin air, it is not you stopping breathing in any dangerous sense, and knowing that in advance makes it a great deal less frightening at two in the morning than discovering it cold.
You will also be up in the night, because altitude makes you pass more urine. That is a sign your body is adjusting properly rather than a nuisance to be suppressed. Keep a bottle and a head torch within reach and accept the interruption.
The appetite
It goes. Food you would eat happily at 1,000 metres is unappealing at 4,000, and the dal bhat that tasted excellent three days ago now looks like a chore. Eat anyway. You are burning a great deal walking, and going into a hard day underfed is how a manageable trip becomes a miserable one. Carbohydrate goes down more easily than fat at altitude, hot drinks work when food does not, and something sweet in your pocket is more use than a perfect meal you cannot face.
The walking
Slower. Noticeably, embarrassingly slower — a gentle rise that would be nothing at home has you stopping to breathe. Porters and local people will walk past you carrying more. This is not fitness, and being fit does not protect you from it; a strong walker who goes up fast is at more risk, not less, because they can outrun their own acclimatisation.
Emotionally, a lot of people are flat or short-tempered for the first days and do not connect it to the altitude. If you are irritable, cold, hungry and not sleeping, that is a normal combination up there and it lifts.
Where the line is
| Ordinary in the first days | Not ordinary — descend |
|---|---|
| Dull headache that eases with rest, fluids and painkillers | Headache that does not respond to anything |
| Broken sleep, vivid dreams, waking with a gasp | Breathlessness while resting or lying down |
| Poor appetite, mild nausea | Vomiting |
| Out of breath on the uphill, fine when you stop | Unsteadiness, stumbling, confusion |
| Passing more urine than usual | A wet, bubbling cough |
Going down is the treatment, and it works fast. Nobody in the mountains will think less of you for it. The one situation to avoid entirely is pressing on because a schedule says so, which is how almost every serious case starts.
How to make the first days easier
Gain height slowly and sleep low. The old rule of thumb about not raising your sleeping altitude by too much in a single day exists because sleeping height, not walking height, is what your body has to cope with. Take a rest day, and on it walk up a few hundred metres and come back down to sleep.
The other half is the itinerary. Trips into Humla and Dolpa start high, because the airstrips are high, so the acclimatisation has to be built in from day one rather than added later. Fewer places and more days in each is better here for reasons beyond comfort, which is the argument in our piece on slow travel in Nepal.
Frequently Asked Questions
Is it normal to get a headache at 3,500 metres?
Yes, a mild one that responds to rest, fluids and simple painkillers is common in the first days. A headache that will not shift, or one that comes with vomiting or unsteadiness, is not normal and means descending.
Why can I not sleep at altitude?
Thin air disrupts the breathing rhythm during sleep, which makes for shallow, broken nights and sometimes waking with a gasp. It improves over several nights as you acclimatise. Sleeping lower than the highest point you reached that day helps considerably.
Why do I have no appetite at altitude?
Appetite drops at height for most people. Eat regardless, favouring carbohydrate and hot drinks, because you are burning far more than usual and eating too little makes every other symptom worse.
Does being fit prevent altitude sickness?
No. Fitness makes the walking easier but does not protect against altitude, and fit walkers sometimes get into trouble precisely because they climb faster than they acclimatise. The rate of ascent is what matters.