Acute Mountain Sickness (AMS): A Comprehensive Collection of Links and Information

If you are a mountain lover like me, you’d probably be dreaming of being somewhere high up in the Himalayas this scorching summer. However, depending on how high you plan to climb you should consider possibility of catching high altitude sickness or AMS. After my brush with AMS a few years ago, I realised how dangerous it could have been had I continued my journey. So as a quick reference guide for fellow mountain lovers, here’s a collection of all the important links that discuss everything about altitude mountain sickness or AMS.

Mountains are calling?
Mountains are calling?

Preparing to raid the mountains?

Let it be Everest Base Camp (5380 m), Inca Trail in Peru (up to 4800 m), Mont Blanc in Swiss Alps (4800 m), or say Kilimanjaro (5900 m). As long as you’re going above a rough benchmark of 2500 m, you are at risk of catching AMS. While there’s no sure shot way of avoiding it, there are plenty of things one can do to reduce its chances. AMS, if neglected, can be very dangerous in that it can even cause death. Although, it can affect anyone globally, the information and links below mostly focus Himalayan trekking/travelling perspective.

Science behind AMS: Why, How, When

There are multiple triggers leading to AMS primary reason being lack of enough oxygen.

Altitude and oxygen unavailability

With higher altitude, the air pressure drops and thus overall oxygen in the air. Although, proportion of oxygen in air is still same, this means with every breath, the amount of oxygen that can be inspired by body reduces with altitude. If the body does not receive enough oxygen it reacts in various ways depending on severity of shortage. The most common early stage symptoms are headache and vomiting.

To give you a perspective, Leh is at an altitude of 3500 m and the (apparent) oxygen availability is only 65% compared to at sea level. While most healthy people adapt to the rarefied air of Leh very quickly, some may need rest even at Leh. It is important is to listen your body and take enough rest if needed. I never feel anything unusual while in Leh.

From aeroplane window, flying at 36000 ft. Oxygen in air at this altitude is less than 18% of at sea level.
From aeroplane window, flying at 36000 ft. Oxygen in air at this altitude is less than 18% of at sea level.

Rapid Ascent

If your climb rate is high, typically because you’re in a van or car and trying to reach higher altitude as quickly as possible, your body does not get time to acclimatize. This is why it is never risk-free to visit Ladakh in under a week. This is also the reason why it is foolish of enthusiastic people to try to reach Leh from Manali rather than from Srinagar. While some of them will not feel any severe symptoms most do. Citing own experience of surviving Manali to Leh journey is equally foolish as it could affect others’ lives who might consider it.  This approach to Leh is a descent from very high altitudes thus is risky, especially because there’s no easy medical help available on the route.

For this reason, it also better to travel by road rather than fly to Leh if you’re a beginner. Flying over the beautiful Karakoram ranges is definitely a great experience, but save it for the return journey.


This can be one of the triggers. Air at high altitudes is not just rare it also is cold. If you are inappropriately dressed, and suffer drop in body temperature, some of the body oxygen is spent in maintaining body temperature. It thus puts additional pressure on body to cope with low oxygen availability. It is therefore very important to wear warm clothes to fight cold and clothes that deflect wind (e.g. wind coats).


If you are on a trekking expedition, make sure you do not overexert thus avoiding additional oxygen demand. Preparatory exercises help. Plan well.

Symptoms of AMS

  1. Constant breathlessness. (Not to be confused with the typical efforts in breathing after strenuous walk)
  2. Severe/constant headache
  3. Tingling sensation in hands and feet
  4. Nausea and vomiting
  5. Drunken gait (ataxia)
  6. Blurred vision
  7. Confusion and irritation

Any or all of these symptoms may be observed and varies from person to person. The AMS has broadly three categories depending on the severity:

  1. Acute (mild) altitude or mountain sickness: mildest and the most common form. This is not life threatening as long as it stays at this stage. I had this on my own solo bike trip. It could have worsened had I continued on my plan to even higher altitudes. (Read my adventure here.)
  2. High Altitude Pulmonary Edema (HAPE): Accumulation of fluid in the lungs that prevents the proper exchange of oxygen. Symptoms associated with HAPE include several from the above list in addition to symptoms like fever and persistent dry cough. This requires immediate treatment or could prove fatal.
  3. High Altitude Cerebral Edema (HACE): Accumulation of fluid in the brain that results in the swelling of the brain tissues. It usually occurs at a very high altitude (above 3,500 m) or extremely high altitude (above 5,550m). Symptoms associated with HACE include many of the symptoms related to HAPE with loss of coordination sense, confusion and higher intensity of them. If no treatment is received immediately death is imminent.

If you think you have some of these, take action immediately.

Dealing with AMS

If this sounds scary, do not worry. It doesn’t mean that the human body cannot cope with the situation at all. In fact, given enough time and exercise (acclimatization) it can adapt to accept the challenging environment. Generally speaking the idea of acclimatization is about allowing body to come to terms with the low oxygen levels in the air yet be able to perform normal behaviour. It takes roughly about 50 hours for most people to fully acclimatize at 3500 m.

So depending on intensity of your high altitude adventure, you can practice exerting at increasing altitudes but at a slow rate. Do simple exercises like climbing steps or brisk walking and taking enough rest. Increase the intensity gradually and rest again.

To give you a perspective, the Indian Army has a unit deployed in the highest battlefield of the world: Siachen. This is at an altitude of 17500ft+ (apparent oxygen level 50% of sea level). The official training program for the soldiers going to Siachen lasts for over 6 weeks. Even after that sometimes, some of them get sick with AMS or its severe versions. Seasoned climbers acclimatize their body by climbing in 1000 feet steps and staying for a day after every 3000 feet to allow the body to adjust to progressive low oxygen conditions.

Some very useful links:

  • Higher Peak:  Percentage Oxygen Reduction Vs Altitude chart
  • LAHDC Health advisory for travel within Ladakh: Government advisory is often displayed on the LAHDC website. Has detailed information by a doctor on symptoms, treatment and self-assessment techniques.
  • Devil on Wheels: Hands down greatest updated knowledge repository for Ladakh/Himachal Pradesh. They also have updated Manali-Leh and Srinagar-Leh route status updates since these invariably get blocked in winter. They also have a lot of very useful information for tourists in these regions including taxi union official charges, bike and car rentals.
  • India Hikes Travel: A great place for some trekking ideas & packages in Himalaya with some really nice information
  • India Mike Forum: A gold mine of information for travel in entire country. The link goes to the Ladakh and Zanskar forum. Contributors are very helpful and asking the right questions or simply browsing through previous questions can help plan your dream mountain trip.
  • British Mountaineering Council: A nice point of reference for alternate reading on dealing with altitude sickness. (Old article)
Transporting my bike that broke down in the sands of Merak. In the meantime, I caught AMS.
Transporting my bike that broke down in the sands of Merak. In the meantime, I caught AMS.

Medication and clothing

It is important to seek professional opinion before going to high altitude places. Although, there’s some common preventive medicines that can be consumed with doctors’ consultation.

  • Diamox (acetazolamide) is most common drug taken to cope with higher breathing rate. It is a prescription drug and any qualified doctor can prescribe it for you subject to your medical conditions. People with any heart conditions should be extra careful regarding the dosage.
  • Paracetamol or similar drugs can be taken for headache or any pains. Again, in consultation with doctors.

It is better to be aware of all the side effects. Unfortunately, if you do hit AMS, seek help from professionals as soon as possible. Portable oxygen cylinders are available in certain places but are not an absolute necessity unless you’re going on an arduous high altitude trek.

No particular clothing can help prevent AMS, but it compliments the recovery. Warm and comfortable clothing can reduce your body’s efforts to stay warm in cold mountain air. Wind as much as cold is an important factor in choosing clothing. In my case, I forgot (!!!) to consider wind and wasn’t prepared for it.


Do not continue until symptoms subside. If needed, return to lower altitude.
Do not continue until symptoms subside. If needed, return to lower altitude.

Seeking help

Make every attempt to seek professional help if you think you have any of these symptoms. Do not delay as it could be fatal. Reaching medical help can be a serious issue if you are traveling in remote areas like Ladakh. Find out about locations of all the health centres on or near your route. In forward areas even in North-Eastern states, Indian army has strong presence and they have a resident doctor in almost all major posts. If outside India, competent authorities make appropriate help available. Find out whom you could turn to before embarking on the trip.

Major medical help centres are at Leh and Kargil. Sonum Norbu Memorial Hospital in Leh is well equipped to handle cases of AMS, HACE or HAPE. There are smaller hospitals in various smaller towns and villages in Ladakh. Some of these medical dispensaries are at Mulbek, Drass, Diskit, Sankoo, Trespone, Padum and Panikhar and have expertise available to treat AMS. The Indian army has many centers and major hospitals around Ladakh and emergency services are provided freely. During my AMS episode, I had myself checked at the army hospital in Karu.

ATM centres are very rare in remote areas. Carry enough cash. Find detailed information on some of the links shared in this post. Alternatively, you can inquire once in Leh. Leh, of course has plenty of ATMs.

View of the mountains and Leh town below
View of the mountains and Leh town below

Sensitive Areas for AMS

It is fairly easy to find out which areas are sensitive with respect to AMS. The risk of catching AMS is beyond altitude of 2500m and quickly increases as you go higher every 500 to 1000 m. AMS can hit anybody above a certain altitude and varies from person to person.In Ladakh, although most places apart from Leh are at altitudes beyond 3500m, there are some areas where there are high chances of suffering from AMS.

  • Changthang: 4450 m (14,846 ft)
  • Tanglang La: 5,328 m (17,480 ft)
  • Pangong Tso: 4,350 m (14,270 ft)
  • Tso Moriri: 4,522 m (14,836 ft)

The same goes for other ranges of Himalayas in Nepal, Sikkim and beyond.

Interesting blog posts:


  1. Prevention is better than cure!
  2. Keep an eye on official announcements in the area you are visiting. Make sure you have updated news and not rumors. Do not take unnecessary risks.
  3. Always begin below 3000m. In my case I travelled to Leh (3500 m) from Kashmir valley which is at much lower altitude. This is a better plan than Manali to Leh.
  4. Acclimate enough and do not climb altitude quickly. Take enough rest in between stops. I stayed in Leh for few days for acclimatization. (This didn’t help me a lot since I climbed too quickly on bike).
  5. Avoid overexertion. Do not take unnecessary risks.
  6. If in a group tour, even if one person falls sick, it ruins the trip. So have a plan B ready.
  7. Stay away from alcohol (basically any drug that impairs normal thinking and responsiveness). Alcohol reduces brain’s responses to effectively fight low oxygen situation. Even if it is very cold, drinking alcohol can actually worsen the symptoms. Find warm clothing instead.
  8. In case if you notice any of the symptoms, do not go to higher altitudes until the symptoms subside.
  9. Seek professional medical help as soon as possible.
  10. Plan well. Stay safe. Adventure with no preparation is foolishness. It could cost you your life.

Here’s some inspiration to still plan that high altitude mountain trip 😉
15 mountain holidays to conquer in your lifetime

Happy Trails!

Happy Trails!
Happy Trails!

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