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Mountain sickness from A to Z. What is mountain sickness? Symptoms, medications, acclimatization. How to avoid it?


Friends, hello! This is Taras Pozdnii. I constantly face the mountain sickness in one way or another. Both personally, when climbing at 8000m, and from observing the participants, when working as a guide on trekking tours in Nepal. I have decided to collect all my experience and to structure the knowledge I received from the lectures and the Internet..

The goal: to write the most simple, understandable to anyone and at the same time complete article about the mountain sickness and acclimatization. And also to answer most of the questions that I hear from the participants and which are regularly repeated, and therefore – are of interest to most.  

About mountain sickness in simple words. What is mining sickness?

Mountain sickness (commonly known as mountain sickness) is a negative reaction of the body to altitude caused by lack of oxygen (hypoxia – oxygen starvation). In the mild stage it is observed almost in all those who ascend to high altitudes. And in the severe – can lead to death.

What are the stages, symptoms and at what altitude begins mountain sickness we will discuss below. And first, a disclaimer:

All of the following is based only on my personal experience and knowledge obtained from the Internet. The information should not be taken as unshakable truth. Run it through your experience, and consult your doctor before taking medication.  

Where mountain sickness comes from – a little bit of theory

At sea level (up to 1000-1500 m) at normal pressure, the oxygen content of the air is about 20.9%. This is the norm to which we are accustomed.

With increasing altitude, the atmospheric pressure decreases and the air becomes “thinner” – thinner. This means that there are fewer oxygen molecules per unit volume. By how much?

At 5000 meters, it is about 50% of normal, at the summit of Mount Everest it is 30-32%.

Уровень кислорода в зависимости от высоты

In practice, this means that we get less oxygen in one breath than we are used to. The body’s first reaction is to breathe more frequently and more deeply. At low altitudes it works – you stop and catch your breath. But if you immediately get to a high altitude (from 3000 m), you will not be able to breathe, even if you are motionless. There comes hypoxia – a lack of oxygen in the blood, brain and tissues. You begin to die little by little.

“What about the Sherpas? After all, they live at high altitudes and feel fine?” – you ask.

Fortunately, our bodies know how to adapt to the lack of oxygen. It just needs time. This process is called adaptation to altitude or acclimatization, and we will consider it below. But first, let’s break down the mountain sickness.

Will I get mountain sickness? Who is at risk?

It’s impossible to know from the bottom whether you’ll get mountain sickness or not. Everything is very individual. A better-trained participant may get sick at 3000m, while a less-trained one will pass the track without any problems. It is possible to single out general theses and tendencies, but even they are very tentative:

These are all just trends. Again, no one can say for sure in advance if you will get altitude sickness. An athlete and an “office plankton” have the same chances.

The body’s normal reaction to altitude

When you get to a high altitude zone (1500-3000 m) your breathing becomes faster and deeper. With standard physical exertion, severe shortness of breath appears. Fluid is retained in the body, which leads to swelling of the face and hands. This happens to absolutely everyone, you should not worry.

Adaptation to new conditions begins: the number of red blood cells (red blood cells that carry oxygen) increases, blood flow accelerates and at the same time the body learns to function in a more economical mode.

This takes time, which most of the time we don’t have. But there is a program schedule, limited vacation time, and no one is going to sit around for months just to get up to 5,000 in peace. We keep climbing, and this will probably lead to a mild stage of mountain sickness.

Infographics: the body’s response to altitude

 Инфографика: как ощущается горная болезнь на разной высоте

Forms of mountain sickness and symptoms

The symptoms of altitude sickness appear in one way or another in virtually everyone. But should you panic and start descending right away? Or is it possible to continue climbing? Everything depends on the stage of mountain sickness. Generally, there are three forms: acute altitude sickness, pulmonary edema and cerebral edema. Let’s discuss each of them.

Acute mountain sickness (AMS, mide)

This is the first stage of mountain sickness, most often appearing 4-12 hours after reaching an altitude of 3,000 m or more. It can have both milder and very unpleasant form. The sensation is usually compared to a severe hangover, and yes, it is indeed similar.

The main symptom that signals the onset of a hangover is a headache. It is usually accompanied by one or more of the following:

You can also diagnose mountain sickness by looking at your face: your skin turns pale, your lips turn blue, and you look a little lost.

All Kuluar groups are equipped with pulse oximeters and we measure blood oxygen saturation every evening and morning. What this is and why it’s needed is at the bottom of the article.

And yet you’re sick. What to do when you get mountain sickness?

First of all, you should not panic and fear a slight mountain sickness. Headache, increased fatigue and lethargy are observed in almost everyone.

Secondly, you should understand that there are no miracle pills for the mountain sickness. But it is possible to help:

Most often there are situations when the mountain sickness is in moderate condition and the group continues to move along the route. In this case, it is important to go as slowly as possible and unload the sick people. If day crossing is not complicated, elevation gain is either absent or small (200-300 m), usually nothing terrible happens. It is important to have a more experienced outside observer. In our groups it is guide, Team Leader Couloir, who watches each of the participants. Even experienced climbers are not always able to estimate their own condition adequately, and beginners do not do it.

If you do not recognize the progressing mountain sickness in time and continue climbing, it may develop into pulmonary and/or brain edema. And this is already a critical condition.

High altitude pulmonary edema (HIGH ALTITUDE PULMONARY EDEMA – HAPE)

With each breath, air enters the lungs and then enters the small air pockets (alveoli). They have very thin walls with good conduction. It is there that blood is enriched with oxygen, and then returns to the heart and further to all organs. At altitude, on the one hand, the pressure in the vessels increases, on the other hand, the permeability of the walls increases, as a result our “air pockets” are filled with fluid. If there is fluid in the alveoli, it means that air cannot get there and the blood is not enriched with oxygen. This is alpine pulmonary edema. It can develop within 2-3 days after being at altitude.

The main symptoms of pulmonary edema:

What to do in case of high altitude pulmonary edema?

With pulmonary edema we have several hours to a day, so we act quickly.

The only “cure” is a quick drop in altitude of 1,000 meters or more. All other measures are only temporary. Helicopter evacuation is ideal. That is why all participants of our high-mountain treks have insurance that includes helicopter evacuation. Read our recommendations for insurance for trekking and climbing.

But often, for one reason or another, starting an instant descent is impossible. Then:

  1. Artificial oxygen. In Nepal they have it in many lodges or medical centers.
  2. Gamow bag – a bag in which the victim is placed and in which pressure is applied, thus simulating a descent. Usually used in conjunction with oxygen, but it is more rare.
  3. Nifedipine is the first drug recommended for pulmonary edema
  4. Dexamethasone is a steroid that can give the patient extra time.

But none of this cancels out as quick a descent as possible.

High altitude cerebral edema. HIGH ALTITUDE CEREBRAL EDEMA (HACE)

The methodology of cerebral edema is still not thoroughly understood. But the point is that fluid enters the brain, increasing the pressure on it and reducing the supply of oxygen. This causes severe headaches that are not relieved by painkillers.

A typical syndrome is “drunken behavior:

Fortunately, cerebral edema is rare. It usually occurs after an altitude of 4,000 meters in less than 1% of hikers, but there have been cases of fixation at an altitude of 2,100 meters as well. Cerebral edema is preceded by an acute stage of mountain sickness and can be paralleled by pulmonary edema. Only in exceptional cases HACE has been detected without previous symptoms of acute mountain sickness.

But what to do if you notice a “drunk” person?

Everything is about the same as in pulmonary edema – the fastest possible descent, at least 1000 m, best of all helicopter evacuation and hospital. While waiting for evacuation: dexamethasone, oxygen and Gamow bag.

Infographic: Forms, symptoms, and first aid for mountain sickness

Инфографика: Формы, симптомы и первая помощь при горной болезни

So, we’ve dealt with the mountain sickness. We know how it appears, what are the stages, symptoms, and what it is fraught with. And now let’s talk about how to avoid it or at least make it as mild as possible – about acclimatization and what to do and what not to do at altitude.

Acclimatization – the body’s adaptation to altitude

Once the body gets into a new environment, it gradually begins to adapt to it. It takes time. In the mountains, like nowhere else, the rule: “The quieter the ride, the farther away you’ll be. The first important step is to make a proper acclimatization schedule. There are several basic rules:

There is an opinion that acclimatization lasts up to three weeks. But I have an exception, based on personal experience. In November-December 2016 I was at an altitude above 4,000 in Nepal for a long time. Trekked to Everest and then an expedition to Mera Peak (6461m) + Island Peak (6189m). After that I was home for two weeks, then trekked in Patagonia for 22 days at low altitude. After one week of rest my partner and I went to Aconcagua (6962m) for the first time. We decided to do it quickly, because he had been higher than 6,000m a month and a half before, too. As a result the ascent to Aconcagua from the entrance to the national park to the exit took 7 days. Practically without acclimatization, with only one night at 5050m and starting from Nido de Condores at 5500m. At the same time my partner fell overnight at 5050 and I helped him down to the base camp. Why is that? Because I had been at altitude in Nepal for a long time and my acclimatization was still good even after almost two months. My partner was at Chimborazo (6384m) and there the whole climb takes three days – such acclimatization disappears very quickly.

The rule works: the longer you are at altitude, the longer the acclimatization lasts.

But, nevertheless, no matter how many eight-thousanders I have under my belt, every time I have to acclimatize again. It’s good that every next time it’s a little easier.

How to feel better at heights? Advice for everyone

Our task is to reduce the amount of stress and unnecessary strain on the body as much as possible.

Infographic: Acclimatization. What to do to make it easier to tolerate altitude

Инфографика: Акклиматизация. Что делать, чтобы легче переносить высоту

Sleeping on high

Dreams at altitude are more vivid and lively than those below. At least for me. Maybe it’s because the sleep is less deep and I can wake up three or five times a night and fall asleep again. This is normal.

If you are plagued by insomnia, you can take half a tablet of Diamax. You can also take the sleep hormone Melatonin. I don’t recommend taking ordinary sleeping pills as they are said to worsen your acclimatization. Some climbers take Cinnarizin for headache before sleep.

Another phenomenon I want to talk about is periodic breathing, the so-called Cheyne-Stokes breathing.

At altitude, we breathe deeply and frequently, as a result of which the concentration of carbon dioxide (CO2) decreases. And it is its excess that stimulates the respiratory center. When we are awake, our consciousness signals us to breathe, and when we fall asleep, it stops. As a result, there is no excess CO2 and there is no signal for breath. There is a breath-holding for 10-15 seconds, then there is an awakening from lack of oxygen and a series of intense breaths. It feels like waking up from gasping for air and trying to catch your breath. It is extremely unpleasant, but not a critical phenomenon that many people experience.

After catching your breath, you can go back to sleep.

Pills for mountain sickness

There are no pills for mountain sickness, and we already know that one treatment is a quick descent. But there are pills to help you better acclimatize.

I won’t touch the subject of ethics of using medicines (as well as artificial oxygen at 8000), but I will say simply – if you are not an athlete and you have nothing to prove to others or yourself, then do your best to get the most of the pleasant sensations from the trek/climb, and not to suffer from mountain sickness.

Acetazolamide, Diamox, Diacarb

Acetazolamide, Diamox, Diacarb  – It’s all the name of one drug.

It is noteworthy that in the former Soviet Union there is still debate about its effectiveness as a preventive measure, while in the Western world it is strongly recommended. From personal experience and observations of hundreds of participants: Diamax really does help to acclimatize better.

Diamax is a diuretic which lowers intracranial pressure, thus relieving symptoms of mountain sickness and facilitating easier and quicker acclimatization.

At the same time there is no “kickback” effect, that is, if you stop taking the drug, nothing bad will happen.

How to take Diakarb (Diamax)

You should start taking it the day before you go to 3000 m. The standard dose is 250 mg, which is one tablet. It is better to take it in the morning. If we feel that all the same, the dose can be increased to two tablets. One in the morning and one in the evening. Remember, Diacarb is a diuretic, so I don’t recommend to take it later than two hours before sleep. Otherwise you will run to the toilet all night and you won’t get enough sleep, which is also bad. It is not recommended to take more than three pills a day.

At altitude, you already lose a lot of fluid, and with Diacarb even more, so drink more water. With urine, minerals and salts are washed out, in particular – potassium and magnesium. Therefore, in parallel with Dicarb is recommended to take Panangin or Asparkam – 1-2 tablets 2-3 times a day.

Be prepared that after about a day of taking Diacarb you will begin to have tingling in your extremities – fingers and toes, even your nose, teeth and feet may feel as if they are numb and itchy. In addition, Diacarb has another property – it changes the taste of carbonated drinks.

Half a tablet can be taken at night if you have trouble sleeping.

Stop taking Diamax the day you reach the maximum altitude and start descending.

Decide for yourself whether to take Diamax, I recommend it to all participants who want a gentler altitude.

Other medications you may need

Vitamins. Two weeks before going to the altitude it is good to start taking a vitamin complex. We need Potassium, Magnesium, Calcium, B vitamins and vitamin C. In the trek excellent showed itself effervescent tablets that dissolve in water.

Ibuprofen, paracetamol are the best remedies for headaches at altitude. The normal dose is two tablets a day. Often recommended paired with Aspirin because it thinners the blood.

Dexamethasone is a steroid that is in the group medicine cabinet. As a last resort in case of high lung and/or brain edema.

How much oxygen do I have in my blood? Measuring saturation

Saturation is the saturation of blood with oxygen and now it can be measured with a small device, which each of our guides on high-altitude programs has – a pulse oximeter.

We measure twice a day – in the morning and in the evening. We do not look at the absolute values, but at the dynamics.

In the evening you climb to a new altitude, for example 4200 m. Body has not yet adapted, breathing is fast, pulse is high. We take measurements, pulse should be 100 and O2 – 80%. In the morning before breakfast we measured again: heart rate was 75 and O2 was 90%. So you’re getting acclimatized. When the body adapts properly, pulse rate should decrease and saturation should increase.

I do not consider pulse oximeter the only basis for any decisions and conclusions, I look only as a whole, based on the symptoms described above. But if the saturation is below 70, I take a very close look at the participant and take him under my special supervision.

At the same time pulse oximeter has a big error, it will show different values on different fingers, and gel polish (especially red) on the nails is a finish. It prevents proper measurement of saturation. So, girls, going high in the mountains, leave at least one finger without nail polish. Thank you for understanding!

Friends, I tried to put all the necessary information about the mountain sickness in one article and convey it in understandable simple language. It was quite voluminous, but hopefully also useful. Let me remind you that everything is based on my experience, and someone may have a different opinion.

The main thing is to go to the mountains safely, tolerate heights easily, and enjoy every moment of the trip!

Kuluar – your life-changing mountain experience!


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