We are sure whenever you research for or plan to go to the Himalayas or any high altitude landscape you will come across these words Acclimatization or AMS. One can easily get confused with the ample amount of unauthenticated information that is available on the internet on this subject. Here is our consolidated ‘All You Need To Know About Acclimatization and AMS’ to eliminate all the confusion and bring to light this self adjusting human phenomenon for a comfortable and healthy high altitude trek.


In simple words when we go higher there is lesser oxygen available for us to breathe and our body creates more Red Blood Cells to increase our oxygen carrying capacity and this process is simply termed as Acclimatization. When we go higher than the altitude our body is ready to acclimatize, this leads to a mountaineering condition like Acute Mountain Sickness (AMS), High-Altitude Cerebral Oedema (HACO or HACE), High-altitude Pulmonary Oedema (HAPO or HAPE) which untreated can lead to more severe conditions, worse case even death. Any of the altitude sickness is a sign that our body is not used to the altitude we are in.

Mild AMS after a height gain is a very common phenomenon. Altitude sickness can be prevented by taking precautions. Understanding and knowing what to do in such a situation gives you no reason to be scared and in return empowers you to take practical decisions which help you get better. This is the soul intention of this consolidation from our side. 


Any place about 7,000 feet as per normal standards or 8,000 feet as per Indian military standards in altitude is said to be in high altitude. Ideally following the mountaineering mantra of ‘Climb High, Sleep Low’ helps our body to get gradually used to the high altitude. 
Many times following this mantra might not possible hence for our complete preparation, here is a list of things one can do when we are in the city, on the mountains, in a potential AMS situation or in a confirmed AMS situation related to you or anyone around you.

Till the natural process of acclimatization completes, our body goes through some changes on it own. Following is a list of changes the body goes through which are a good sign of acclimatization:
  • Heavy Breathing: Since there is lesser amount of oxygen in the air hence the amount of oxygen we can take in one breath reduces. This gives our body the need to be take more breaths to compensate for the lesser amount of oxygen available. A remarkable thing about the human body is that it automatically increases the red blood cells count in the body and once this process gets completed we restore to our usual breathing.
  • Shortness of breath after little exercise or exertion
  • Disturbed sleep
  • Change in the breathing pattern while sleeping
  • More frequent urine 

  • Health Checkups: Make sure you visit your doctor and get a health checkup before your trek. Take your doctor’s advice seriously specially on your blood pressure and haemoglobin.
  • Plans Your Climbs And Height Gain Properly: It is true that the mountains don’t adjust as per us but we adjust as per the mountains, having said that, in an ideal scenario if you are climbing higher than 10,000 feet then:
  • Increase your sleeping altitude only by approximately 1,000 to 1,600 feet.
  • Take a rest day for ideally every 3,500 feet gained.
  • Consult With Your Doctor for the use of AMS prevention medicines like Diamox
  • Start Building A Habit of Drinking More Water
  • Find out the altitude of the base camp and if it lies in high altitude then try to reach there by road for a gradual height gain or keep an extra day for acclimatization when you reach the camp. Do not exert on this day. 


Few precautions from our side can ensure a comfortable ascend into the infinite views, the endless snow and priceless memories. Things you would keep in mind to prevent altitude sickness:
  • Drink As Much As Water/Fluids As You Can: The more healthy fluids you drink, faster are the chances of acclimatization.  
  • Don’t Climb Too Quickly: Our bodies are unique and require their own time to get used to the changes. The faster you go, the lesser time you get to acclimatize.
  • Keep Your Outdoor Leaders Informed: If you feel any noticeable change, do inform your outdoor Leaders. They will know what to do.
  • Do Not Sleep Immediately After A Height Gain: When the body sleeps it slows down its metabolism and affects the acclimatization.
  • Do Not Cover Your Ears: The ears maintain the balance of the body, do not shield them with the changes happening in the air.
  • Eat Enough Food: Loss of appetite is a common situation at high altitudes but no matter how tired we are it is only food which gets us back on our feet and helps us acclimatize. 
  • Acetazolamide aka Diamox: Diamox is one of the most widely used medicines to prevent AMS. These are most suitable for people who have been known to have problems in the past or who unavoidably have to ascend more quickly than recommended. The routine use of acetazolamide before ascent is not recommended. The better strategy for prevention is to ascend slowly and to be aware of any developing symptoms.
  • If symptoms of AMS develop, then delay further ascent.

The body has a beautiful way to speak to us. It always gives us symptoms before progressing to something serious. Usually the symptoms take 6 to 12 hours to appear after arriving at the higher location and vary from person to person. Here is a list of symptoms which will help you identify AMS:
  • Headache
  • Loss of Appetite
  • Fatigue
  • Nausea
  • Feeling light headed or dizzy
Use of Oximeter: Oximeter is a pocket size device into which one can put their finger and find out their current oxygen levels and heart beat. After a height gain, it is normal for the oxygen level (number) to be lower than the usual. If after spending a few hours in the new campsite the oxygen level (number) keep getting lower or gets constant at a lower number and doesn’t increase towards a more normal number (the normal number depends on the height gain or the trek you are on) then this is a sign of AMS.

Lake Louise Score Sheet: Lake Louise Score Sheet for AMS is a technique where one can answer a few questions and get to understand their situation better. Following is the sheet. All you have to do is answer the 5 questions below and calculate your total. After you find out your total, compare your total against the results mentioned below.
3 to 5 = Mild AMS 
6 or more = Severe AMS
If you feel you or any found around you is getting affected by AMS, inform your Outdoor Leaders immediately. They know what to do. AMS can happen to anyone if proper care is not taken irrespective of the experience. Everybody is different. It is not connected to fitness. Do not underplay or ignore the symptoms.

3 to 5 = Mild AMS

6 or more = Severe AMS

IMPORTANT: Remember that any symptoms at altitude are altitude illness until proven otherwise.

Here is a list of immediate things you should do if you or someone you know is showing the signs of AMS:
  • Inform your Outdoor Leaders immediately. They know what to do. AMS can happen to anyone if proper care is not taken irrespective of the experience.
  • Stop your ascent immediately and rest at the same altitude. Usually the symptoms improve within 24 Hrs with basic painkillers like paracetamol (under the supervision of the Outdoor Leaders).
  • If the symptoms do not improve within 24th hours or get worse before 24 hours, descent immediately. There is no medicinal cure to altitude sickness, the only cure is to descend to a lower height where the body has acclimatized before.
  • It is highly likely that a short descend and rest will make you feel better. It may still be better to climb up provided that you have recovered completely. Do not go back up under any circumstance if you do not feel 100% recovered.

trekking , himalayas , himalayantrek , uttarakhnad , northindia , blog , clothing , altitude


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