High Altitude: Acclimatization and Illnesses

Yogesh Sarkar

Hi every one last year when I was planning to go to Ladakh I came across this guide on Acute Mountain Sickness and found it to be a great help.

For those heading to Ladakh and Spiti reading this guide is a must in order to prepare oneself for the AMS that you will encounter at High Altitude Places. Please go through this guide and in case you have been to High Altitude Places before then please go ahead and let us know what you did to combat AMS.


What is high altitude?


What Causes Altitude Illnesses




The depth of respiration increases.


The body produces more red blood cells to carry oxygen,


Prevention of Altitude Illnesses







• If symptoms increase, go down, down, down!







Preventive Medications



Acute Mountain Sickness (AMS)

AMS is common at high altitudes. At elevations over 10,000 feet (3,048 meters), 75% of people will have mild symptoms. The occurrence of AMS is dependent upon the elevation, the rate of ascent, and individual susceptibility. Many people will experience mild AMS during the acclimatization process. Symptoms usually start 12-24 hours after arrival at altitude and begin to decrease in severity about the third day. The symptoms of Mild AMS are headache, dizziness, fatigue, shortness of breath, loss of appetite, nausea, disturbed sleep, and a general feeling of malaise. Symptoms tend to be worse at night and when respiratory drive is decreased. Mild AMS does not interfere with normal activity and symptoms generally subside within 2-4 days as the body acclimatizes. As long as symptoms are mild, and only a nuisance, ascent can continue at a moderate rate. When hiking, it is essential that you communicate any symptoms of illness immediately to others on your trip. AMS is considered to be a neurological problem caused by changes in the central nervous system. It is basically a mild form of High Altitude Cerebral Edema (see below).

Basic Treatment of AMS

The only cure is either acclimatization or descent. Symptoms of Mild AMS can be treated with pain medications for headache and Diamox. Both help to reduce the severity of the symptoms, but remember, reducing the symptoms is not curing the problem.

Moderate AMS


Severe AMS

Severe AMS presents as an increase in the severity of the aforementioned symptoms, including shortness of breath at rest, inability to walk, decreasing mental status, and fluid buildup in the lungs. Severe AMS requires immediate descent to lower altitudes (2,000 - 4,000 feet [610-1,220 meters]).

There are two other severe forms of altitude illness, High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE). Both of these happen less frequently, especially to those who are properly acclimatized. When they do occur, it is usually with people going too high too fast or going very high and staying there. The lack of oxygen results in leakage of fluid through the capillary walls into either the lungs or the brain.

High Altitude Pulmonary Edema (HAPE)

HAPE results from fluid buildup in the lungs. The fluid in the lungs prevents effective oxygen exchange. As the condition becomes more severe, the level of oxygen in the bloodstream decreases, and this can lead to cyanosis, impaired cerebral function, and death. Symptoms include shortness of breath even at rest, “tightness in the chest,” marked fatigue, a feeling of impending suffocation at night, weakness, and a persistent productive cough bringing up white, watery, or frothy fluid. Confusion, and irrational behavior are signs that insufficient oxygen is reaching the brain. One of the methods for testing yourself for HAPE is to check your recovery time after exertion. If your heart and breathing rates normally slow down in X seconds after exercise, but at altitude your recovery time is much greater, it may mean fluid is building up in the lungs. In cases of HAPE, immediate descent is a necessary life-saving measure (2,000 - 4,000 feet [610-1,220 meters]). Anyone suffering from HAPE must be evacuated to a medical facility for proper follow-up treatment.

High Altitude Cerebral Edema (HACE)

HACE is the result of swelling of brain tissue from fluid leakage. Symptoms can include headache, loss of coordination (ataxia), weakness, and decreasing levels of consciousness including, disorientation, loss of memory, hallucinations, psychotic behavior, and coma. It generally occurs after a week or more at high altitude. Severe instances can lead to death if not treated quickly. Immediate descent is a necessary life-saving measure (2,000 - 4,000 feet [610-1,220 meters]). There are some medications that may be prescribed for treatment in the field, but these require that you have proper training in their use. Anyone suffering from HACE must be evacuated to a medical facility for proper follow-up treatment.

Other Medications for Altitude Illnesses

Ibuprofen is effective at relieving altitude headache.

Nifedipine rapidly decreases pulmonary artery pressure and relieves HAPE. Breathing oxygen reduces the effects of altitude illnesses.

Gamow Bag (pronounced ga´ mäf) This clever invention has revolutionized field treatment of high altitude illnesses. The bag is basically a sealed chamber with a pump. The person is placed inside the bag and it is inflated. Pumping the bag full of air effectively increases the concentration of oxygen molecules and therefore simulates a descent to lower altitude. In as little as 10 minutes the bag can create an “atmosphere” that corresponds to that at 3,000 - 5,000 feet (915 - 1,525 meters) lower. After a 1-2 hours in the bag, the person’s body chemistry will have “reset” to the lower altitude. This lasts for up to 12 hours outside of the bag which should be enough time to walk them down to a lower altitude and allow for further acclimatization. The bag and pump weigh about 14 pounds (6.3 kilos) and are now carried on most major high altitude expeditions. Bags can be rented for short term trips such as treks or expeditions.

Cheyne-Stokes Respirations


There are inherent risks in traveling at high altitude. The information provided here is designed for educational use only and is not a substitute for specific training or experience. Princeton University and the author assume no liability for any individual’s use of or reliance upon any material contained or referenced herein. This paper is prepared to provide basic information about altitude illnesses for the lay person. Medical research on high altitude illnesses is always expanding our knowledge of the causes and treatment. When going to altitude it is your responsibility to learn the latest information. The material contained in this article may not be the most current. Copyright © 1995 Rick Curtis, Outdoor Action Program, Princeton University.
I do tend to get sick at higher altitudes, but normally that's when I"m being driven around. Don't have enough experience on high altitude riding to know. But a great article.

Yogesh Sarkar

Manas at what did you encounter AMS?

I once experienced it at an altitude of 10000fts, that day I was tired and hadn?t had any sleep in past 30 hours and I was feeling sick after eating the worst Rajam ? Chawal of my life. On the other hand I didn?t experience AMS at Rohtang (13050ft).

Yogesh Sarkar

Another thing, I have heard drinking Glucose while traveling at high altitude helps, will be trying this on my ladakh trip.

Scorpion King

Active Member
whew long article there buddy and i must confess i did not read the whole thing but it is true this ams thing is a pretty psychological phenomenon

best thing is to keep your mind busy, body relaxed, stomach half full, if in a car ask the driver to drive slow enjoy the scenery

keeping the windows down helps.

also keep taking deep breaths for a while at regular intervals

Yogesh Sarkar

Rohan AMS is not psychological phenomenon!

It is physical and the reason behind it is lack of oxygen at high altitude. Due to scarcity of oxygen body has a hard time carrying out normal bodily functions. The danger of getting a serious case of AMS is quite true and real.

The moment you start climbing Rohtang La after Marhi you will know what I am talking about.

Scorpion King

Active Member
oh k i think i should not have used the word psychological here

i had read something about ams somewhere else as well and it is very similar to what u have written but to quote your own article

some people get it some people dont

now what i had read
(and i hope i can find that thread or article again (for posting) coz i have been reading so much from so many sites i cant remember where i read it from)
was something like this the amount of effect caused by ams does not depend on a persons physical fitness a physically weak person with low stamina can show no signs of ams at high altitudes where as a fit person may be affected by it. it all comes down to how fast your brain can trigger your body to react to the decreasing air density.

thats all :)


Super Moderator
Staff member
Cheyne-Stokes Respirations ... Now I know what I experienced at the camp above Gette village in Spiti. That was about 4300 meters... higher than Rohtang pass. But inspite of all the high altitude camps/rides etc, I have never really experienced the most basic symptom of AMS, headaches.