Walking Among the Clouds: A Guide to High-Altitude Trekking

Combating AMS and the other perils of hiking in the high mountains.

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Conquering a trek is an unparalleled feeling. It’s even better when you’re not sick from the altitude. Photo: Maria Ly/ Flickr/ Creative Commons


What is high altitude?

Elevations in the excess of 8,000 ft are said to be at a high altitude.

What does this high-altitude business mean?

Travelling beyond these altitudes deserves a little more respect than a normal holiday. The geek take: air is composed of 21 per cent oxygen, which remains constant as you ascend, but with the air getting thinner, there is less oxygen available (to breathe). This makes every task seem more difficult; you find yourself getting tired faster.

Anything else?

Yes. You are likely to experience some physiological problems until your body gets used to being at the higher altitude you have arrived at. This “settling in” is called acclimatisation. The time taken to acclimatise varies from person to person – it could take anything from one to five days.

During the acclimatisation period, you may have any one or a combination of the following symptoms: headache, nausea, vomiting, insomnia or poor sleep, loss of appetite, lethargy and fatigue, difficulty in breathing, shortness of breath, a general feeling of malaise. My favourite symptom is flatulence! The sum of these symptoms is called altitude sickness or acute mountain sickness (AMS).

All told – it’s not nice!

Is this serious?

Acclimatisation is a normal adaptive process. If you do develop symptoms, they will typically pass in a few days. However, if you do not help your body to adapt (resting, and drinking plenty of non-alcoholic fluids, is key to the process among other precautions), your symptoms might get worse. It could then develop into pulmonary oedema (fluid entering the lungs), and cerebral oedema (fluid entering the brain cavity).  These conditions are serious, and if they are not immediately attended to, you will die.

What’s the summary here?

Most people can go up to 8,000ft with minimal effect. But if you haven’t been in a high altitude location before, it’s important to be cautious. People in good health should not be alarmed by this piece, but if you have a medical condition such as high blood pressure, heart or lung disease, you must take the advice of a doctor who has experience with the effects of altitude (eg an Army or BSF doctor). If you follow a regimen that includes drinking a lot of fluids (you must stay hydrated), eating well, and rest, rest, and rest, you will make a painless transition, and have a great vacation. Quite simple!

What happens if I fall sick with serious AMS?

All of us will feel less-than-optimal for a couple of days. Even I do. This is expected, and is no big deal. However, if you are macho and decide not to follow the advice outlined below, normal altitude sickness may progress to advanced stages of pulmonary oedema or cerebral oedema. If this happens, everything must be done to prevent the condition from deteriorating.

Under no circumstances should a person with AMS be allowed to proceed to a higher altitude.

Typically, medical facilities are non-existent in high-altitude regions, and hospitals are too far for rapid access. Heli-evacuation in India is not an alternative, which is sad, since rapid and immediate evacuation (to a lower altitude) is imperative for a patient showing symptoms of advancing AMS. Descent is a sure cure.

What can I do?

Oxygen? Nah. Even if you are carrying bottled oxygen, though it may provide relief, it will not fix someone suffering from advancing Altitude Sickness. Heard of portable acclimatisation chambers? (Google “Gammow Bag”.) Even if you are part of an organised climbing or trekking group and happen to have one, it will only provide temporary relief. Immediate and rapid descent is imperative.

What happens if I get advanced AMS, and the symptoms don’t subside?

There is only one sure cure for AMS – and luckily that is a sure fix: Descend, descend, descend!

As soon as you are at a lower altitude (where you were earlier asymptomatic), the symptoms will alleviate, and will start reversing immediately. Remember that pulmonary and cerebral oedema are not fatal in themselves, but they will lead to death if left unattended. (See Fact file below.)

Can I do anything to assist acclimatisation?

The process of acclimatisation is unpredictable and varies from person to person. You can help yourself by adhering to the basic rules:

Rest is critical. Do not exert yourself.

Keep yourself hydrated. Drink lots of fluids – four litres through the day. In fact, as a general rule, if your urine has any colour, you need more liquid intake. Do not wait to feel thirsty before you drink. Keep a one-litre bottle accessible at all times, and drink from it to keep track of your daily consumption. Don’t make the mistake of keeping your fluid intake low to avoid the discomfort of getting up at night to pee.

Stay off alcohol. While tea is great for the sugar kick and the warmth, it is a diuretic, so don’t consume more than a couple of cups.

You will probably have no desire to eat, since altitude dampens appetite, but you must force yourself to ingest at least small quantities of light food (70 per cent of which is carbs) if you cannot handle a full meal.

Is there any medication I can take for altitude sickness?

Diamox (acetazolamide) is of some value in the prevention of AMS, however, despite the amount of money spent on research on altitude and its effects, there is no conclusive evidence that it does help!

Whether or not one takes Diamox is obviously a matter of personal choice – travel to high altitudes is quite possible without it.

High Altitude Cerebral Oedema High Altitude Pulmonary Oedema Altitude Trek

Acclimatisation is imperative on high-altitude treks; make sure you know what it entails. Photo: Maria Ly/ Flickr/ Creative Commons (bit.ly/1jxQJMa)

High-Altitude 101

•    Be careful after crossing 3,000m.
•    It is recommended to not gain more than 300m in sleeping height per day.
•    “Climb high and sleep low.” This is the maxim used by climbers. You can climb more than 1,000 ft (300m) in a day as long as you come back down and sleep at a lower altitude.
•    In addition to the above, take a rest day and stay at the same altitude, after every 1,000m of gain, or every two or three days.
•    If you begin to show symptoms of moderate altitude illness, don’t go higher until symptoms decrease.
•    You can take regular medication for headaches, or if you feel like throwing up.
•    If symptoms increase, immediately go down, down, down.
•    Keep in mind that different people will acclimatise at different rates. Make sure all of your party is properly acclimatised before going higher.
•    Stay properly hydrated. Acclimatisation is often accompanied by fluid loss, so you need to drink lots of fluids to remain properly hydrated (at least four litres per day). Urine output should be copious and clear.
•    Take Diamox 125mg, twice daily, two days before arriving at high altitude.
•    Take it easy; don’t over-exert yourself when you first get to a high altitude. Light activity during the day is better than sleeping because respiration decreases during sleep, exacerbating the symptoms.
•    Avoid tobacco and alcohol and other depressant drugs including barbiturates, tranquilisers, and sleeping pills. These depressants further decrease the respiratory drive during sleep resulting in a worsening of the symptoms.
•    Eat a high carbohydrate diet (more than 70 per cent of your calories from carbohydrates) while at altitude.
•    The acclimatisation process is inhibited by dehydration, over-exertion, and alcohol and other depressant drugs.
•    If you have exhibited symptoms of AMS during previous visits to high altitude you may be predisposed to getting AMS in subsequent visits.

Emergency Primer

High-Altitude Cerebral Oedema (HACE) and High-Altitude Pulmonary Oedema (HAPE) occur only in exceptional cases. Here’s a primer:

•    Any person with AMS should be watched over very carefully.
•    Under no circumstances should a person with AMS be allowed to sleep alone.
•    Observe for confusion, disorientation, clumsiness, unsteady gait or hand coordination, irrational behavior, or if unusually quiet or noisy.
•    If there is any doubt, assume HACE is present.
•    Make the patient walk in a straight line, placing heel against toe with each step. An inability to do this is an important clinical test for HACE.
•    It is imperative that the patient does not exert themselves even in the smallest way.
•    Plan for immediate evacuation to a lower altitude (where they were asymptomatic earlier). This is critical.
•    Administer oxygen if available.
•    A drug called Dexamethasone, if available, to be given 8mg initially, followed by 4mg every six hours.
•    A patient with the symptoms described above will become lethargic, sleepy, and eventually slip into a coma. This could take as little as 12 hours.

•    Any person with AMS should be watched over very carefully.
•    Under no circumstances should a person with AMS be allowed to sleep alone.
•    Do note that HAPE can appear dramatically without obvious symptoms of AMS.
•    Watch out for uncomfortable awareness of breathing, lowered tolerance to exercise, and longer recovery from exercise.
•    In HAPE, this will progress to breathlessness, and a dry cough, that with time will become bubbly and wet, and may be blood-stained. (Do note that a dry cough is quite common at high altitude, and may not be due to early HAPE).
•    A low fever will develop.
•    If there is any doubt, assume HAPE is present.
•    It is imperative that the patient does not exert themselves even in the smallest way.
•    Plan for immediate evacuation to a lower altitude (where they were asymptomatic). This is critical
•    Administer oxygen if available. Oxygen provides immediate and dramatic relief.
•    The patient should be kept warm.
•    Sit the patient upright.
•    Nifedipine 10mg, if available, to be administered by breaking a capsule and placing it under the tongue, followed by 20mg four times daily.
•    Since HAPE is generally associated with AMS and HACE, Dexamethasone should be given if available.




  • Milan Moudgill is a graphic design consultant, based in New Delhi. For the last decade he has been travelling in the Himalayas, and organising extreme treks, in an attempt to bring the mountains closer to the uninitiated and inexperienced.