Altitude Sickness on Indian Peaks: Signs, Prevention and Rules
Go up slowly. Go down fast.
A clear guide to altitude sickness for trekkers and climbers heading into the Indian Himalaya: where it starts, the early signs, the two emergencies (HAPE and HACE), the sleeping-altitude rule that prevents most of it, and how real Himachal climbs and Ladakh's 48-hour advice build it into the plan.
- From 2,500 m 8,200 ft and up
- Above 3,000 m sleep ≤ 500 m higher a night
- Headache? stop going up
- Worse? go down 300–1,000 m
Mountains of India › Altitude Sickness on Indian Peaks
Last verified 15 Oct 2026
What is high altitude sickness?
High altitude sickness is the body’s reaction to thin air when you go up faster than it can adjust. It can begin from about 2,500 m (8,200 ft): a headache with nausea, tiredness or dizziness. Above 3,000 m, sleep no more than 500 m higher each night. If symptoms get worse, go down. Heights of every big summit are on our list of the highest peaks in India.
Altitude sickness, also called acute mountain sickness or AMS, can affect anyone who sleeps high before their body has adjusted. The US Centers for Disease Control and Prevention (CDC) says the risk applies to unacclimatised people sleeping at about 2,450 m (8,000 ft) or higher, and sometimes lower; the UK’s NHS puts it above about 2,500 m. It is common: about one person in five gets it after going quickly to 2,500 m, and about two in five after going quickly to 3,000 m.
Most guides stop at the definition. This one applies the rules to the mountains of India: how fast the road gains height from Manali into Lahaul, why flying into Leh is a special case, and how Himachal climbs such as Yunam Peak and Friendship Peak build rest days into the climb.
This guide is general information, not medical advice. See a doctor before a high-altitude trip, especially with a heart or lung condition or if you are pregnant.
Altitude sickness symptoms: AMS, HAPE and HACE
Acute mountain sickness usually starts 2–12 hours after you arrive at a new height, often during or after the first night. The CDC describes it as a headache plus at least one of: loss of appetite, dizziness, tiredness, nausea or vomiting. It feels like a hangover. Two rarer forms are emergencies.
| Condition | What happens | Signs to watch for | What to do |
|---|---|---|---|
| AMS (acute mountain sickness) | The body has not yet adjusted to the height | Headache with nausea, tiredness, dizziness or poor appetite | Tell your team, stop going up and rest at the same height. If it gets worse or does not improve in a day, go down |
| HACE (high-altitude cerebral edema) | Swelling of the brain; the end stage of AMS | Confusion, unusual drowsiness, stumbling or loss of coordination | Emergency: go down at once and get medical help |
| HAPE (high-altitude pulmonary edema) | Fluid in the lungs | Chest congestion, cough, falling behind, then breathless even at rest; frothy or bloody cough; blue or grey lips | Emergency: go down at once and get medical help. It can get worse fast |
Emergency signs. Confusion, poor balance, breathlessness at rest, a frothy or bloody cough, blue or grey lips or extreme drowsiness mean the person needs medical help and needs to go down, if it can be done safely.
How to prevent altitude sickness: the 500 m rule
The safest way to avoid altitude sickness is to give your body time. What counts is the height where you sleep, not the highest point you touch in the day.
- Above 3,000 m (9,800 ft), sleep no more than 500 m (1,600 ft) higher each night.This is the CDC’s rule for gradual ascent.
- Add an extra night for every 1,000 m (3,300 ft) you gain.The NHS adds a rest day every 3–4 days above 3,000 m.
- Climb high, sleep low.Above about 3,000 m, most climbers carry loads or walk higher during the day and come back down to sleep.
- Avoid big one-day jumps.The NHS advises against going from below 1,200 m (3,900 ft) to above 3,500 m (11,500 ft) in one day, and against flying straight to a high place.
- Drink enough and skip the alcohol.Both are on the NHS list. Medicines are a decision for your doctor; going down is the treatment that always works.
Acclimatisation on real Himachal climbs
Roads in Himachal climb fast. From Manali at about 2,050 m (6,700 ft), the drive through the Atal Tunnel reaches Jispa at about 3,150 m (10,300 ft) in a day, and the next day’s drive up the Manali–Leh highway reaches the Bharatpur tent camp at about 4,650 m (15,300 ft). That second night is about 1,500 m higher: three times the 500 m rule. This is why well-built itineraries add rest days where the jumps are big.
| Climb | Sleeping heights, night by night (about) | Where the rest days sit |
|---|---|---|
| Yunam Peak, 6,111 m / 20,049 ft | Manali 2,050 → Jispa 3,150 → Bharatpur 4,650 → Bharatpur → base camp 5,200 → base camp | A full day at Bharatpur, then a second one at base camp before the summit |
| Friendship Peak, 5,289 m / 17,352 ft | Manali 2,050 → Bakarthach 3,300 → Lady Leg 3,850 → Lady Leg → summit camp 4,200 | A rest and load-ferry day at Lady Leg base camp; nightly gains above 3,300 m stay close to the 500 m rule |
| Deo Tibba, 6,001 m / 19,688 ft | Manali 2,050 → Chhika 3,160 → Seri 3,620 → Tainta 4,100 → Tainta → camp 1 5,100 → camp 1 → summit camp 5,500 → summit camp | Rest days at base camp, camp 1 and summit camp; load ferries before each move up |
Camp heights are approximate and taken from each peak page’s route. Summit heights come from our peak dataset.
Our guide to expedition camping explains how camps are spaced, and what to wear for cold high camps is in our layering guide.
Altitude sickness in Ladakh: the 48-hour advice
A flight from Delhi lands you in Leh, at about 3,500 m (11,500 ft), within hours: exactly the kind of jump the NHS warns about. Ladakh’s official tourism advisory asks every visitor to allow at least 48 hours for acclimatisation on arrival in Leh.
Ladakh Tourism advises
- Day 1: complete rest.
- Day 2: short, easy walks only.
- No alcohol or smoking in the first 48 hours, and no sleeping pills.
- Go down immediately if severe symptoms develop.
- SNM Hospital in Leh offers emergency oxygen.
Why it matters
- In June 2022 the Leh authorities made 48-hour acclimatisation mandatory after a run of altitude-related deaths among tourists.
- Road trips into Ladakh and Spiti gain height more slowly than a flight, but long one-day drives over high passes can still break the 500 m rule.
Who gets altitude sickness? Fitness does not protect you
Myth
- “I’m fit, so I won’t get it.”
- “Drinking lots of water prevents it.”
- “A headache at altitude is nothing.”
What the sources say
- The CDC says training and physical fitness do not affect the risk. Fit people often climb too fast.
- Drinking enough helps you feel well, but only a slow ascent prevents AMS.
- A headache at a new height is AMS until proven otherwise: stop going up.
The best predictor. How you did before at a similar height and ascent rate is the best guide to how you will do next time. Tell your doctor and your guide about any past problems at altitude.
On a guided climb, Himachal’s adventure rules require registered guides to be medically fit and certified in first aid and CPR. Foreign expeditions to Indian peaks also need insurance that covers altitude-related illness and rescue, under the Indian Mountaineering Foundation’s expedition rules.
Altitude sickness questions
At what height does altitude sickness start?
It can start from about 2,450–2,500 m (8,000–8,200 ft) and is common above 3,000 m (9,800 ft), especially if you go up quickly.
What are the first symptoms of altitude sickness?
A headache plus nausea, tiredness, dizziness or poor appetite, often after the first night at a new height. It feels like a hangover.
How do you prevent altitude sickness?
Go up slowly. Above 3,000 m, sleep no more than 500 m higher each night and add an extra night for every 1,000 m. Drink enough and avoid alcohol.
Can fit people get altitude sickness?
Yes. Training and fitness do not lower the risk, and fit people often climb too fast.
What should I do if I get altitude sickness?
Tell your team, stop going up and rest at the same height. If it gets worse or does not improve in a day, go down 300–1,000 m.
What are HAPE and HACE?
HAPE is fluid in the lungs: a cough and breathlessness even at rest. HACE is swelling of the brain: confusion and stumbling. Both are emergencies: go down and get medical help.
Is 48-hour acclimatisation compulsory in Leh?
Ladakh’s official advisory asks visitors to allow at least 48 hours of rest on arrival in Leh, and the Leh authorities made it mandatory in 2022.
Should I take medicine to prevent altitude sickness?
That is a decision for your doctor. Going down is the treatment that always works.
Climb with acclimatisation built in
Planning a first Himalayan summit? We pair you with a registered Himachal outfitter and certified guides on an itinerary with rest days where the height jumps are big, and add hotels and transfers: one plan, one quote.
