Nepal Stories and Tips

Altitude Trekking

Female Porters Photo, Mount Everest, Nepal

On a Slow Death and How to Cheat It

There isn’t a sadder way of spoiling the perfect vacation than climbing beyond the altitude limit where the body can get suitable amounts of oxygen from the atmosphere. The problem is that this limit is not steady, it varies as the body gets accustomed to the altitude; a process known as acclimatization.

Enjoying an altitude trek demands from the trekker knowledge of his – or hers – acclimatization stage at every moment and how much altitude gain is possible to get in a given day without suffering damage. A point usually confused is that physical fitness is not related to acclimatization. Ahead of me in the trek was a group from north Europe. They did the short trek, from Lukla, and advanced without any acclimatization stops. Among them was a triathlon professional. Shortly after they crossed the 4200m, the champion collapsed at once despite his superb fitness and was evacuated within a pressurized plastic bag. Less fit members of that group were not affected at all. The issue is individual; nobody can take decisions better than the well-informed trekker.

Above 5000m, the issue gets tricky. At those altitudes the trekker is near the human limit. It isn’t as dramatic or well advertised as the dangers of reaching the Everest summit, but the danger is real. Above 7000m the body cannot acclimatize and begins dying, that’s why climbers rush up at those altitudes. Above 5000m acclimatization is slow and demands long stays; or for those aware of their exact acclimatization stage a quick ascent to and descent from the desired sight.

What is high?

As explained above, the response to altitude is personal. 80% of the population would not experience any troubles between 2000 and 3000m. However, above that everybody needs acclimatization.

How do I know my limits?

The only way to find one’s body response to altitude is reaching it. That means the first time this is done extreme care should be taken. Be aware of sudden dizziness and headaches; unexplained fatigue is also a sign. Try walking in a straight line heel to toe and standing on one leg. If failing any of these simple tasks, then altitude is taking its toll on the trekker.


The air pressure diminishes with altitude. That means the body gets less oxygen molecules per breath.


Acclimatization is the process which allows the body overcoming the diminishing pressure. It includes several adjustments. The simpler one is increasing the breathing rate; this is important and would be expanded later on. Beyond that the pressure in pulmonary arteries is increased, so that blood can reach portions of the lung which are not used during sea level breathing. Moreover, the body produces more of an enzyme that facilitates the release of oxygen from the hemoglobin to the body tissues. Finally, the body increases the number of red blood cells, so that there is more hemoglobin available for carrying oxygen; in parallel it decreased the amounts of liquids in the blood, thus an increased urination rate appears. The last processes takes time and demand stays at given heights until new cells are produced.


Beyond the preliminary signs described above, the trekker would find harder to walk and climb as altitude is gained: a peculiar feeling of suffocation appears. There is no air, despite nothing obstructing your airways. Scary. All these signs are collectively known as Mild (or Acute – depending on the signs) Mountain Sickness (AMS).

Dizziness can cause accidents, but the real danger is of a different nature. At certain altitude – different for every person – fluid leaks from the capillaries to the lungs and brain. This process is known as edema and is life-threatening. High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE) happen to people going too high too fast or going very high and staying there. Both are dangerous, demanding evacuation to lower altitudes and a complex follow up.

Go Down!

If vomiting, unreasonable weakness or ataxia (bad coordination) appear, wait for nothing: go down along the fastest and safest path. Mild Mountain Sickness had set on, and the Acute variation is on its way: don’t wait. Down, down, down!


Luckily, prevention is easy, demanding just awareness of what is sensible to achieve during the trek. For those having read the "Trek" part of this journal is obvious that the first rule is advancing from low altitudes by foot. Reaching a high altitude by car or air and starting the trek from a high point (for example, Lukla) is the sure way of getting in troubles.

Then, walk at your own pace until the 3000m line is reached. Problems are not expected, but perform the test described above at least once a day. After crossing the 3000m upwards don’t sleep 300m above the altitude spent the night before. That means during the day you may climb higher than 300m, as long as you descend to that altitude difference for the night. Three nights should be spent between the 3000 and 4000m line. If at those altitudes the AMS symptoms appear, there is only one course of action: go down! Don’t panic, don’t run. Just go down as fast and safe as possible; if following the precautions all along, all the symptoms would reverse soon after crossing the last night altitude downwards.

Afterwards, for every 1000m accumulated, take a day off at that altitude. During that day exercising lightly is recommended; that means walking along the same altitude.

Due to the nature of the process, drinking lots of water and eating well helps the acclimatization. Monitoring is essential; perform the tests described above daily and check out the urine color: it should be clear, otherwise the body is dehydrating. Alcohol, tobacco and any depressant drugs would worsen the symptoms; avoiding them is recommended.


All that is nice, but what happens when a storm approaches and threatens spoiling the end of the trek? In the trek described in this journal, the first winter storm was announced shortly before I reached the 5000m line. All the medical books in the world wouldn’t have convinced me to walk down and wait until the next season.

Luckily, I had a cheat in my pocket. While in Kathmandu, I had purchased a strip of Diamox (Acetazolamide) and kept it with me. There is no need of prescription and all drugstores in Thamel (see that entry in this journal) would eventually offer it once they find out the customer is about to take an altitude trek.

Eventually I didn’t use it, but I had the knowledge that if AMS signs appeared I would be able to artificially increase the rate of my breath – that’s what this drug performs – and thus gain some extra time.

Accordingly, I climbed directly from the Pyramid to Kala Pattar – about 600 meters – without the additional acclimatization day I needed for the 5000m mark. Near Kala Pattar, mild altitude sickness symptoms appeared. Moreover my face and fingers swelled up – but I made it. A few hours later, when I was back at the Pyramid – and after a well earned pot of tea – the symptoms disappeared.

In my way down, the storm began and the paths were sealed until the spring.

Been to this destination?

Share Your Story or Tip