Altitude sickness is the group of symptoms your body produces when it cannot get enough oxygen at height, and it becomes a real risk above roughly 2,500 metres. Your hospital placement in Nepal almost certainly sits far below that line. The trek you book for the fortnight afterwards does not. So the short answer is this: you are not at risk on the ward, you are at risk on the trail, and the single thing that protects you most is climbing slowly rather than swallowing a tablet. This guide covers what altitude sickness feels like, how fast you can safely ascend, which symptoms mean stop, and which mean go down tonight.
Altitude sickness, which clinicians usually call acute mountain sickness or AMS, is what happens when you climb faster than your physiology can adapt. Air at 4,000 m still contains 21% oxygen, but the pressure driving that oxygen across your alveolar membrane is far lower, so your arterial saturation falls. Your body compensates by breathing faster and by shifting fluid around. The headache, the nausea and the terrible first night's sleep are that compensation going badly.
The NHS describes the usual picture plainly: you can get altitude sickness at more than 2,500 metres above sea level, you are more likely to get it if you travel or climb up quickly, and symptoms typically begin 6 to 10 hours after arriving at height. The main ones are headache, loss of appetite, feeling or being sick, tiredness, dizziness and difficulty sleeping. Most cases settle in 1 to 3 days if you simply stay put.
Two rarer conditions sit at the dangerous end of the same spectrum. High altitude cerebral edema (HACE) is AMS plus altered mental state or ataxia. High altitude pulmonary edema (HAPE) is non cardiogenic pulmonary oedema, and it can appear without any AMS at all, usually 1 to 4 days after reaching altitude. Both are emergencies. Both improve with descent faster than with anything else you can carry in a rucksack.
Here is the bit students underestimate. Being 23, fit and a medical student protects you from almost none of this. Susceptibility is largely individual, and a previous episode is one of the few genuine predictors.
Secure your spot for your internship abroad now.
No, and that is worth saying clearly before anyone panics. travel4med places students in Pokhara, and both Pokhara and Kathmandu lie comfortably below the 2,500 m line the NHS names. You will not develop altitude sickness walking to the hospital, and you do not need acclimatisation days built into your medical elective in Nepal itself.
The risk arrives the moment your placement ends. Nearly everyone tacks a trek onto the trip, and the classic routes climb hard. The Mustang study describes its own district as sitting between 2,500 m and 3,000 m, with Muktinath at 3,800 m, Lo Manthang at 3,840 m, the Kora La at 4,660 m and the Thorong La pass at 5,416 m. On the Khumbu side, the Himalayan Rescue Association's aid post at Pheriche sits at 14,343 feet, which is about 4,371 m.
| Where you are | Approximate elevation | Altitude sickness risk |
|---|---|---|
| Pokhara and Kathmandu | Well below 2,500 m | Not a concern |
| Lower Mustang villages | 2,500 m to 3,000 m | Risk begins here |
| Muktinath | 3,800 m | Real, plan rest days |
| Pheriche aid post, Khumbu | About 4,371 m | High, medical help on site |
| Thorong La pass | 5,416 m | High, and no easy descent |
So treat your trek as a separate medical plan from your placement, with its own preparation, its own kit and its own insurance check.
Common enough that a district hospital sees it as routine seasonal work. A case control study published in PLOS Global Public Health on 7 February 2025 recruited patients at Mustang district hospital in Nepal over 13 weeks, from 1 September to 30 November 2023, and compared 63 people who presented with altitude illness against 63 matched controls who had been to the same heights without it.
Of those 63 cases, 67% had AMS, 20% had HAPE and 13% had HACE. That last figure is the one to sit with. Roughly one in three people sick enough to reach that hospital had a form of altitude illness that kills people.
The same paper reports something more useful than a prevalence figure: what separated the cases from the controls. Rapid ascent carried an adjusted odds ratio of 6.41 (95% CI 2.36 to 17.54). A previous history of illness carried 10.20 (95% CI 2.70 to 38.46). Not taking prophylaxis carried 10.01. Age, sex, smoking and fitness did not reach significance. It is a small single hospital study, so read the odds ratios as a direction rather than a national statistic, but the direction is unambiguous.
Awareness matters too, and it is measurable. The authors cite a 12 year follow up of trekkers around the Annapurnas in which AMS prevalence fell from 43% to 29% while awareness of the condition rose from 80% to 95%. Reading this page is not a trivial intervention.
Use two thresholds, not one. The first says stay at this height. The second says lose altitude tonight, in the dark if necessary.
| Level | What you notice | What you do |
|---|---|---|
| Mild AMS | Headache, nausea, poor appetite, bad sleep, dizziness | Stop climbing. Rest at the same height. Paracetamol or ibuprofen, fluids, no alcohol |
| Not improving | Symptoms the same or worse after 1 day | Descend 300 to 1,000 m |
| Emergency | Confusion, ataxia, hallucinations, breathless at rest, frothy or bloody sputum, blue or grey lips or nail beds, very drowsy | Descend immediately and get medical help |
Those emergency features come straight from the NHS urgent advice box, and they map onto HACE and HAPE. The rule that matters is the boring one: never climb higher on the day you develop symptoms, and never let a symptomatic person in your group sleep higher than they slept last night.
One practical warning for medical students specifically. You will be the person in the teahouse everyone turns to, probably three weeks after you first held a stethoscope on a ward in Pokhara. Be honest about your limits, and use descent rather than diagnosis as your default. Descent is the treatment you can actually deliver.
Preventing altitude sickness is mostly an itinerary problem, not a pharmacy problem. Build the schedule first, then decide about tablets. The NHS prevention advice, combined with the ascent definition the Mustang authors used, gives you a workable plan:
Planning a placement in Nepal and a trek afterwards? travel4med organises clinical clerkships, nursing internships, practical year placements and observerships in Nepal, Sri Lanka, Bali and Zanzibar, and we will talk through the health and safety side with you before you book. Arrange a free consultation or read more about our Nepal location.
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Acetazolamide is the standard prophylactic drug, typically 125 mg or 250 mg twice daily in the studies described here, and the Mustang authors found not taking it was strongly associated with becoming a case. Note the direction of that finding carefully: it is an association in a small observational study, not a licence to climb fast. The same paper states plainly that prophylaxis does not prevent symptoms if the ascent is too rapid.
Two things follow for you. First, this is a prescription decision for a doctor who knows your history, not something to buy over a counter in Thamel the night before you leave. Second, if you do carry it, carry it alongside a plan, not instead of one.
Partly volunteers, and partly nobody. The Himalayan Rescue Association is a voluntary non profit formed in 1973 to reduce casualties in the Nepal Himalaya. It staffs seasonal aid posts at Manang on the Annapurna circuit and at Pheriche in the Khumbu, plus the Everest ER camp at Everest base camp, with volunteer doctors during the trekking seasons.
That network is genuinely good, and it is also thin and seasonal. Between posts you are relying on your group, a satellite messenger if you carry one, and a helicopter that will only fly in certain weather and only after somebody has agreed to pay for it. Read that last clause twice.
Often not, and this is the single most expensive mistake on this page. Many student travel policies exclude trekking above a stated altitude, commonly somewhere between 3,000 m and 4,500 m, and helicopter evacuation is a separate benefit again. A Thorong La crossing at 5,416 m sits above almost every standard ceiling.
Before you pay for anything, pull up the policy wording and look for three specific things: the maximum trekking altitude covered, whether mountain rescue and helicopter evacuation are included, and whether repatriation has a cap. Our guide to medical elective insurance walks through how to read those clauses, and the packing list for a clinical internship abroad covers what to actually carry. While you are checking documents, it is worth reading up on the other health risks that travel with you, from travellers diarrhoea to tuberculosis on the ward itself, and on getting around Sri Lanka and Nepal safely.
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