High altitude sickness also referred to acute mountain sickness (AMS), is the effect of the environment at higher elevations (above 2440 meters) on the body. You don’t have to be attempting an 8000-er to experience this. It is common among skiers, travelers, hikers, and climbers and should be taken very seriously. I have had my fair share of experience and knowledge on the matter and in the following article, I will share with you some useful information regarding its nature and prevention.

The first time

Back in 2014, I got high at 5895 meters on top of one of the most common of the 7 summits – Kilimanjaro. The trip was an impulsive one, and I did not understand what altitude does to one’s body. Hell, I haven’t even been to my homeland’s higher peaks which are below 3000 meters. Kilimanjaro is a peak where often inexperienced enthusiasts are exposed to the risk of acute mountain sickness due to the short itinerary.

The usual culprit in the onset of either condition (HAPE,HACE) is a sudden ascent from a relatively low altitude. A peak like Kilimanjaro, in Tanzania, is a perfect breeding ground for HAPE or HACE , as hundreds of trekkers each month go from 3,000 feet to 19,000 in a matter of days. – Ed Viesters

Within less than 48 hours we made an ascent from Horombo hut at 3700 meters to Kibo hut at 4750 meters where we had a rest in the afternoon, only to prepare for a summit after midnight. Gaining 1000 meter within a day is normally an optimal case at altitude even if you are experienced and acclimatized. Something I was not. After midnight we went for the summit and gained another 1145 meters, only to find ourselves some 18 hours later back to the Horombo Hut. That makes 2195 meters altitude gain in less than 48 hours.

I am a stubborn person and the challenge ahead was one I welcomed. As the night’s chill took a toll on me, so did a rapid heartbeat, dizziness, loss of orientation and one hell of a cough, ripping my ribs from the inside. Thanks to the tight itinerary we were quickly back down. Within a day, I was back to a cheerful mood, ready to celebrate the success of what marked my first of many to come adventures up in the thin air.

On the top
On top of Kilimanjaro, 2014

What causes AMS?

The higher you go, the lower the levels of oxygen in the air. Air pressure also decreases, so even though the ratio of the oxygen to the nitrogen remains the same, the molecules are spread further apart. Thus, one portion of breath brings in less oxygen. Exertion at higher elevations adds to the cause. As with any other exertion, your body needs to transport oxygen, but when there is a lack, you suffer.

To compensate, the heart pumps faster, so it can carry blood flow to the oxygen-starved tissues. That compensation has its limits. Once the heart reaches its maximum rate, the body shuts any further exertion to preserve itself. Our bodies are complex and smart so within hours of getting to high altitude it starts producing red blood cells to accommodate to the environment. Red blood cells help transport the increasing scares oxygen, but this also works to a point. First up, new red blood cells take 7 to 10 days to mature. If the blood gets too thick it can form clots. That, in a worst case scenario, may end up in a deep vein thrombosis. If it breaks loose, it may cause a serious problem in the lung, called a pulmonary embolism, a heart attack or stroke.

Types and Symptoms

Mild AMS

Many people experience that during their acclimatization process. One can feel the effect of the altitude within 12-24 hours upon arrival. At night the symptoms worsen due to poor oxygenation. This is because the respiratory drive is decreased while we are at rest. Common symptoms are:

* headaches * dizziness * fatigue * shortness of breath * loss of appetite * nausea * disturbed sleep * general feeling of malaise *

It is normal, not to say inevitable, to experience any of those symptoms if you are going up. Even if you gain elevation by the book, it is probable that at some point you will feel discomfort. As long as it is mild, some rest and either stopping or even going down may have a miraculously curing effect. Mild AMS is treated with pain medications and should not cause abortion of your trip or expedition.

Nowadays, a drug called DIAMOX is popular in terms of prevention. If you are a trekker or a tourist, you don’t need it. You could manage going high in a way that is controllable and needs no medications. If you are a mountaineer, using DIAMOX is like cheating and it is very disrespectful. I have never used it and I would not recommend it.

High altitude image
A bit swollen somewhere high in the tent

Moderate AMS

While the mild AMS does not interfere with your normal activity, this one does. Ibuprofen won’t do the magic here. Been there, done that. Your head is like a ticking bomb. Your eyelids are swollen. Someone is giving you pasta and you not only feel like vomiting, you do so. Appetite- there is no appetite. Sleeping is a problem. We are talking about the next level of feeling shitty. The symptoms are:

* severe headache * nausea * vomiting * increased weakness * fatigue * shortness of breath * loss of coordination * irritability * rapid heartbeat * swelling of limps and face

If you are experiencing a moderate altitude sickness, it will be challenging to walk the straight line. You know, the heel to toe test. That would seem hard, not to say impossible. You will probably look like someone completely different. I tend to have my face swollen at altitude. In such a case, it is best to descend. Some 300-600 meters will make a huge difference and will ensure you get down before you become incapable of walking. A day or two at a lower elevation should make you feel better. Give yourself time to recover and acclimatize before you go up again.

Descend 500m or more; if descent is not possible, use a hyperbaric chamber or administer low-flow oxygen (1-2 lts/min); if descent is not possible and oxygen is not available, administer acetazolamide (250 mg BD), or dexamethasone (4 mg PO or IM q 6 hourly), or both until symptoms resolve.

Severe AMS

This is where we talk of HAPE (high altitude pulmonary edema) and HACE (high altitude cerebral edema). If you are suffering from any of those conditions, you need to get down. When experiencing Moderate AMS, your ego and power of will may help you continue going up. If you experience HAPE or HACE, though, you feel the urgency of descending.

High altitude pulmonary edema is caused when hypoxia increases both arterial flow and blood pressure to the lungs to a point when fluid leaks from the capillaries. It is something like drowning in your own fluids. The symptoms are:

* difficulty breathing at rest * moist cough * severe weakness * drowsiness * cyanosis * tachycardia * tachypnea rales

Administer oxygen (4-6 lts/min until condition improves, and then 2-4 lts/min to conserve supplies); descend as soon as possible, with minimal exertion, or use a portable hyperbaric chamber; if descent is not possible or oxygen is not available, administer nifedipine (10 mg PO initially and then 30 mg of extended release formulations PO q 12-24 hrs); add dexamethasone if neurological deterioration occurs.

Altitude sickness
Normally, I look better 😉

High altitude cerebral edema is like the pulmonary edema, except the leakage is in the area around the brain rather than the lungs. As the fluid leaks out because it is entrapped within the rigid structure of the skull, it creates pressure to the soft tissue of the brain with devastating results. Symptoms include:

* hallucinations * extreme mental confusion * ataxia (loss of full control over the body)

Initiate immediate descent or evacuation; if descent is not possible, use a portable hyperbaric chamber; administer oxygen (2-4 lts/min;) administer dexamethasone (8 mg PO or IM or IV initially and then 4 mg q 6 hourly); administer acetazolamide if descent is delayed.

Second time

They say the first time hurts the most. Yet, with altitude sickness, one can never predict. Edema does not necessarily affect the unfit or inexperienced ones. If you have suffered ones, it doesn’t mean you are likely to get it again. If you have been several times up high with no problems, that, too, does not mean you are invincible.

My second exposure to altitude was in the Alps on a classic climb of Mont Blanc. While the story had its twists and turns, I felt no symptoms. My acclimatization was by the books and I felt strong. So was the case when I first visited the Khumbu region and did the EBC trek with a hike up to Kalla Patar. With no problems and well acclimatized, I even took part in a focus group which aimed to examine the effects that altitude has on humans. It turned out that my memory and sharp mind became duller above 5000 meters. Apart from being just slower, I suffered none further.

Himalayan views
Himalayan views

My second suffering, though, was as epic as the scenery in which it took place. Even though I felt great during the acclimatization, with having slept at 5600 meters and been to 6000 meters, what came after was like from a horror movie. Stuck at 6000 meters for 5 nights and 6 days, I developed HAPE. Trust me when I say, this is pure torture. Breathing is painful, and every breath is followed by a horrific cough that tears your torso from the inside. Sleep is impossible. Darth Vader could only envy your vocal complexity. Going down became the most important thing. I have been coughing for days, suffocating, until a doctor at base camp gave me a pill. I took it. It was steroids and together with my descent; it helped for a rapid recovery.

What happens to the body at altitude?

* Your respiratory rate increases.

* Your resting heart rate increases.

* You body initiates the production of red blood cells.

* The higher you go, you maximum heart rate is reduced. The body turns on preservation mode.

* Your heart stroke volume drops.

* For any given workload, your heart must beat more to deliver sufficient oxygen to the working muscles.

* The higher you go, the less oxygen is available to the red blood cells.

* Plasma volume decreases.

* Blood pH shifts to become more alkaline.

Tips & Tricks

  1. Train the diaphragm. At altitude, the respiratory muscles – primary the diaphragm – require a greater portion of your cardiac output than the muscles being used for locomotion. The best way to train the muscles of your diaphragm is by doing long duration aerobic efforts. Higher volumes of heavy breathing over long periods is what you should focus on before your trip/expedition.
  2. Climb slowly. If you are not acclimatized, avoid flying to or driving to high altitudes. One reason the Everest view hotel at 3880 meters shut down in the past was due to deaths of people who were flown there. This is also the reason behind the oxygen masks you will find in the rooms. While on your trek/approach up, do not exceed 500 meters of elevation gain per day. It is advisable to have a rest day after ascending 1500 meters for the body to adapt. Here, too, one becomes stronger during the rest. If you feel mild AMS symptoms, slow down or stop.
  3. All in on carbs. Yep! No low-carb diets while you are up high. You need calories as at altitude everything is magnified, including your need for eating well. Try to eat light but often. Every two hours is ideal. Appetite is a great indicator of acclimatization. Eat simple foods that are palatable and easy to digest.
  4. Hydration. I go for at least 3 liters a day. I know people who manage with 1 liter and others who need 5 or even 6 liters a day. While the amount is individual, it is important to stay well hydrated. Alcohol does not fall into the proper hydration process even though it is liquid.
  5. Caffeine? I love coffee. A high altitude Tzvetichino is my specialty. And so, I embarked on a mission to find an excuse for the otherwise thought to be bad at altitude coffee. Altitude expert Dr. Peter Hackett concludes:

Fears of dehydration from caffeine are exaggerated. Its effect on ventilation and cerebral circulation and its action as a psychostimulant are likely to be helpful at altitude. Caffeine may also help exercise performance at altitude. Importantly, habitual caffeine users should not discontinue caffeine because of travel to altitude.  

6. Sleep lower. Depending on how high you are going and the essence of your expedition, it is better to go higher during the day and sleep at a lower altitude. As mentioned, altitude sickness gets worse at night and having a good night rest is vital for your well-being.

7. Drugs and supplements. I will not get into the serious stuff such as Dexamethazone and other steroid drugs. What could be crowned as the most universal drug ever is the Aspirin. Having one a day helps to thin the blood. Ibuprofen can help with altitude headaches. It is also good to have an anti-nausea drug. I use Degan, but in different countries, the name of the drug differs.

Ginger and garlic are the two foods all altitude adventurers swear by. There is no scientific evidence of their efficacy, but I can tell you that altitude sickness has some vampire root as garlic does miracles in keeping it far from you.

Electrolytes are a good way to stay hydrated and to give some extra taste to the liquids you drink.

More Himalayan views
More Himalayan views


Acclimatization to altitude is a wondrously complex process. Despite its suffering, it is also accompanied by breathtaking views which have nothing to do with HAPE. Going high requires from one to summon up all reserves of will he has stacked. Only true motivation can resist high altitude atrophy. In an alien-like environment, it is only natural for one to experience extraterrestrial sensations. One such is to admire the beauty of an alpine setting. For your body to adapt to altitude, it is important to increase its ability to deliver oxygen to the muscles and its efficiency with which those muscles use oxygen. There is no single formula as we are all different. What is important is to enjoy the process and stay healthy.

Explore. Exhale. Enjoy.


Sources: Training for the New Alpinism by Scott Johnston & Steve House; No Shortcuts to the Top by Ed Viesturs; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4923381/

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