It's a common worry for first-time trekkers: will I need an oxygen tank to reach Everest Base Camp? The good news is no.
Quick answer: no, trekkers don't use supplemental oxygen to reach Everest Base Camp (5,364 m) or Kala Patthar (about 5,545 m). The air there has only about half the oxygen available at sea level, so you need to acclimatise gradually. Guides may carry oxygen or use it at lodges for emergencies only.
How thin is the air?
The percentage of oxygen in the air is the same as at sea level, but the air pressure is much lower, so each breath contains less oxygen. At base camp, it's roughly half the sea-level amount.
How trekkers cope
- A slow ascent, with acclimatisation days at Namche Bazaar and Dingboche.
- Drinking plenty of water.
- Walking slowly and steadily.
- Sleeping lower than the highest point reached each day when possible.
When oxygen is used
If someone develops serious altitude sickness, oxygen can buy time while they descend or wait for a helicopter. Descent is the most important treatment.
Who uses oxygen on Everest?
Climbers use supplemental oxygen high on the mountain, typically above Camp 3, not trekkers going to base camp.
Read our altitude sickness guide and EBC difficulty guide.
Oxygen along the trail
| Place | Altitude | Effective oxygen compared with sea level (approx.) |
|---|---|---|
| Kathmandu | 1,400 m | About 85% |
| Lukla | 2,860 m | About 72% |
| Namche Bazaar | 3,440 m | About 67% |
| Dingboche | 4,410 m | About 59% |
| Lobuche | 4,940 m | About 55% |
| Gorak Shep | 5,164 m | About 53% |
| Everest Base Camp | 5,364 m | About 51% |
| Kala Patthar | About 5,545 m | About 50% |
| Everest summit | 8,848.86 m | About 33% |
The figures are approximate and vary with weather and season, but they show why every step at Gorak Shep feels harder than at Namche.
What acclimatisation does
When you go higher, your body responds in stages. Within hours, you breathe faster and deeper, and your heart beats faster. Over the next few days, your kidneys adjust the chemistry of your blood so you can breathe more effectively, and you urinate more. Over days to weeks, your body produces more red blood cells to carry oxygen. These changes take time, which is why sensible itineraries gain no more than about 300–500 m of sleeping altitude a day above 3,000 m, with a rest day every 1,000 m or so. On the Everest trail, the classic acclimatisation stops are Namche Bazaar and Dingboche, where you spend an extra night and climb a nearby hill before returning to sleep.
A sensible acclimatisation itinerary
| Day | Sleep at | Altitude |
|---|---|---|
| 1 | Phakding | 2,610 m |
| 2 | Namche Bazaar | 3,440 m |
| 3 | Namche (acclimatisation hike to the Everest View Hotel) | 3,440 m |
| 4 | Tengboche or Deboche | 3,820–3,860 m |
| 5 | Dingboche | 4,410 m |
| 6 | Dingboche (hike towards Nangkartshang) | 4,410 m |
| 7 | Lobuche | 4,940 m |
| 8 | Gorak Shep, visit Everest Base Camp | 5,164 m |
| 9 | Kala Patthar at dawn, descend to Pheriche | About 4,370 m |
Symptoms to watch for
| Condition | Symptoms | What to do |
|---|---|---|
| Acute mountain sickness (AMS) | Headache plus nausea, tiredness, dizziness, poor appetite or poor sleep | Rest, don't go higher, drink fluids; descend if not improving |
| High-altitude pulmonary oedema (HAPE) | Breathlessness at rest, cough, gurgling chest, extreme fatigue, blue lips | Descend immediately; oxygen and medical help |
| High-altitude cerebral oedema (HACE) | Confusion, loss of coordination, severe headache, drowsiness | Descend immediately; oxygen and medical help |
HAPE and HACE are emergencies that can be fatal within hours. Never leave someone with these symptoms alone, and never let them descend unaccompanied. See altitude sickness guide.
Pulse oximeters
Many guides carry a pulse oximeter, a small clip that measures the oxygen saturation of your blood (SpO2) and your heart rate. At sea level, healthy people have saturations of about 95–100%; at Namche, 85–92% is common; and at Gorak Shep, readings in the high 70s or low 80s are normal for a well-acclimatised trekker. The trend matters more than a single number, and how you feel matters most: a low reading in someone who feels well is less worrying than a "normal" reading in someone who is confused or breathless. Our guides check trekkers' oxygen levels each morning and evening on high treks.
Medicines
Acetazolamide (Diamox) can help prevent and treat mild altitude sickness by speeding up acclimatisation. It is a prescription medicine with side effects such as tingling fingers and more frequent urination, and isn't suitable for everyone, including people with sulfa allergies. Discuss it with your doctor before you travel. Other medicines, such as dexamethasone and nifedipine, are used for severe altitude illness and should be carried by expedition doctors or used on medical advice. No medicine replaces a slow ascent and descending when necessary.
Oxygen and helicopters in emergencies
Lodges in the upper Khumbu, the Himalayan Rescue Association clinic at Pheriche, and some trekking teams keep oxygen cylinders for emergencies. Portable hyperbaric chambers (Gamow bags), which simulate a lower altitude, are also available in some places. These buy time, but the definitive treatment is descent, on foot, on a horse, carried by porters, or by helicopter when the weather allows. See helicopter rescue.
Who should be cautious
People with heart or lung disease, severe anaemia, sickle-cell disease or a history of severe altitude illness should talk to a doctor before trekking to Everest Base Camp. Age and fitness don't predict who gets altitude sickness, but a slow pace and an honest conversation with your guide help everyone. See EBC difficulty.
Tips for coping with thin air
- Walk slowly: your guide's pace may feel too slow at first; it isn't. Aim to be able to talk while walking.
- Breathe deeply and rhythmically: some trekkers find "pressure breathing", a forceful out-breath, helps on steep sections.
- Drink 3–4 litres a day: hydration doesn't prevent altitude sickness on its own, but dehydration makes everything worse.
- Eat well: carbohydrates are easier to use at altitude; keep eating even when your appetite drops.
- Avoid alcohol and sleeping pills: both depress breathing at night.
- Keep warm: cold increases the body's demand for oxygen.
- Sleep with your head raised: an extra pillow or a rolled-up jacket can make breathing at night easier.
- Be honest: tell your guide about headaches, nausea or breathlessness, even if they seem minor.
Sleeping at altitude
Many trekkers sleep badly above about 4,000 m. You may wake often, feel short of breath, or notice a pattern called periodic breathing, in which breathing slows or pauses for a few seconds and then speeds up. This is common and usually harmless, but it can be alarming for room-mates. Acetazolamide can reduce it. If someone can't be woken easily, or is breathless lying down, it may be a sign of serious altitude illness and needs urgent attention. See Diamox for trekking.
Helicopter tours and oxygen
Passengers on Everest helicopter tours fly from Kathmandu (1,400 m) to landing points around 5,000–5,500 m in a couple of hours, without acclimatisation. Because of this, helicopter companies limit the time on the ground to a few minutes, and many carry oxygen on board. People with heart or lung conditions should check with their doctor before booking. See helicopter tour guide.
Training for thin air
You can't fully prepare for altitude at sea level, but good aerobic fitness makes the trek more comfortable, because you will work less hard at any given pace. Build endurance with long walks, hill climbing, cycling or running for two to three months before the trek. Some trekkers use altitude tents or masks at home; these may help a little with acclimatisation, but they are no substitute for a sensible itinerary. Previous experience at altitude, for example on a trek to 3,000–4,000 m, is useful because you learn how your own body reacts. See how to train for EBC.
Our approach
Our Everest Base Camp itineraries include acclimatisation days at Namche and Dingboche, our guides monitor oxygen saturation and symptoms every day, and we carry first-aid kits and arrange emergency oxygen where needed. Most of our trekkers reach base camp and Kala Patthar comfortably without ever needing supplemental oxygen. Contact us to ask about our Everest treks.