Altitude Sickness in Nepal: Symptoms, Prevention & When to Turn Back

Trekking in Nepal often means walking above 3,000 m, where the air is thin and the body needs time to adjust. Acute mountain sickness (AMS), a form of altitude sickness, affects many trekkers and can become dangerous if ignored. This guide explains what altitude sickness is, how to recognise the symptoms, and practical steps to prevent it while exploring the Himalayas.

If you are planning a high-altitude route, first explore our Nepal treks to understand which journeys match your fitness level, time and comfort.

What is altitude sickness?

Altitude sickness occurs when the body cannot get enough oxygen from the reduced atmospheric pressure at high elevations. The CDC’s travel health guide notes that hypoxia at about 3,050 m reduces arterial oxygen saturation to around 88–91%. AMS usually occurs after a rapid ascent, and the body needs time, also called acclimatisation, to adjust.

Two life-threatening forms of altitude illness — high-altitude cerebral edema (HACE) and high-altitude pulmonary edema (HAPE) — can develop if mild AMS is ignored.

Common symptoms

AMS symptoms can feel like an intense hangover. Headache is usually the main symptom and may be accompanied by loss of appetite, dizziness, fatigue or nausea. Symptoms typically begin within 2–12 hours of arrival at altitude and often worsen on the first night.

Children may show irritability or unusual tiredness instead of clearly describing a headache. If left untreated, or if one continues climbing, AMS can progress to HACE or HAPE. HACE may include confusion, loss of coordination and drowsiness, while HAPE may include chest congestion, cough, extreme breathlessness and sometimes bloody sputum.

These severe forms are medical emergencies requiring immediate descent and treatment.

If you are unsure whether a trek is suitable for your group, compare routes through our all Nepal packages before finalising your plan.

Prevention strategies

Ascend gradually

The most reliable prevention is a slow and steady ascent. The Wilderness Medical Society recommends not sleeping more than 500 m higher each night once above 3,000 m, and taking an extra rest day for every additional 1,000 m gained.

Many itineraries for Everest Base Camp and Annapurna Base Camp include these principles by spending extra nights in acclimatisation hubs such as Namche Bazaar, Dingboche, Ghorepani or similar mountain villages.

For first-time trekkers, choosing a route with planned acclimatisation days is more important than choosing the shortest itinerary.

Planning a high-altitude trek? A safer itinerary is not always the fastest one. Sustainable Journeys Nepal can help you choose a trek pace that gives your body time to adjust. Talk to our travel team.

Build in rest days and acclimatisation hikes

Once you reach 2,500 m or higher, schedule at least one rest day every few days. On rest days, do short “active acclimatisation” hikes to slightly higher elevations and then return to sleep at your base altitude.

This helps the body adapt to lower oxygen levels while still allowing enough rest for the next stage of the trek.

Stay hydrated and fuelled

Drink plenty of water to combat dehydration, which can worsen AMS symptoms. Many trekkers aim for around 3–4 litres per day, but your exact requirement depends on weather, activity level and your body.

Avoid alcohol during the first stage of high-altitude travel because it can affect hydration and sleep. Eat balanced meals rich in carbohydrates to provide energy for long walking days.

If you want a professionally managed trek with meals, route planning and guide support included, browse our guided trek packages.

Consider medication only with medical advice

Acetazolamide, commonly known as Diamox, is sometimes prescribed to help with acclimatisation. Dexamethasone may also be prescribed in specific cases. However, these medicines should only be used after consulting a qualified doctor.

Medication should never replace gradual ascent, rest days and proper decision-making on the trail.

Medical note: This blog is for general travel awareness only. It is not medical advice. Always consult your doctor before taking altitude medication or travelling to high-altitude regions.

Monitor yourself and your group

Carry a small pulse oximeter if possible, but do not rely only on numbers. Listen to your body and observe your group.

If you or a fellow trekker experiences persistent headache, severe fatigue, vomiting, confusion or difficulty walking in a straight line, treat it seriously.

What to do if symptoms appear

If you develop mild AMS, stop ascending and rest at the same altitude. Symptoms often improve within 12–48 hours. Over-the-counter painkillers can help with headaches, and anti-nausea tablets may ease stomach upset.

However, never ascend to a higher sleeping altitude if symptoms persist or worsen.

If your condition deteriorates despite rest or medication, or if you experience signs of HACE or HAPE, descend immediately and seek medical assistance. Portable hyperbaric bags or evacuation by helicopter may be necessary in remote areas.

For safer travel planning, you can also contact Sustainable Journeys Nepal before booking your route, especially if your group includes first-time trekkers, children, seniors or travellers with medical concerns.

Safe ascent itinerary examples

For the Everest Base Camp trek, most itineraries stretch over 11–14 days and include rest days in Namche Bazaar and Dingboche to allow acclimatisation. Days typically gain 300–500 m in sleeping altitude and the route avoids sudden large overnight jumps.

Annapurna Base Camp trekkers often start at Nayapul or nearby trailheads and spend nights in villages such as Ghorepani, Chhomrong, Dovan or Deurali before ascending toward the base camp area.

Following a reputable itinerary prevents going “too high too fast.” Before finalising your trek, compare options on our Nepal treks page or browse all Nepal packages for guided routes.

Emergency protocols

If a member of your group shows severe AMS or HACE/HAPE symptoms, stop ascent immediately and keep the person warm and hydrated.

Administer oxygen if available and start descent as soon as possible, ideally with a guide or porter’s assistance. Medicines such as dexamethasone or nifedipine may be used in some altitude emergencies, but only under professional advice.

In remote regions without immediate evacuation options, a portable hyperbaric chamber can temporarily simulate a lower altitude and stabilise the patient until descent is possible.

Role of experienced guides

Hiring an experienced guide ensures that you have someone trained to recognise and manage altitude illness. Guides plan acclimatisation days, monitor trekkers for symptoms and coordinate emergency rescues if necessary.

This is especially useful on high-altitude routes like Everest Base Camp, Annapurna Base Camp, Langtang Valley and other Himalayan treks.

Need help choosing a safer route? Sustainable Journeys Nepal can help you select the right trek based on altitude, season, fitness level and comfort. Plan your trek with us.

Plan Your Trip with Sustainable Journeys Nepal

Altitude sickness is preventable and manageable when you respect the mountains and your body. Trekking slowly, hydrating, taking rest days and being aware of symptoms will increase your chances of a safe and enjoyable journey.

To explore the Himalayas confidently, consider booking a guided trek with Sustainable Journeys Nepal. Our experienced team prioritises your safety, follows best acclimatisation practices and helps you enjoy Nepal’s stunning landscapes at a comfortable pace.

Explore our Nepal treks, view all packages, or contact us to plan a safer Himalayan journey.