In this article, I would like to share information about the causes, symptoms, and management of altitude sickness. I would like to emphasize, that the medications listed here for prophylaxis and treatment are general recommendations and the goal of my post is to share information about the management of altitude sickness. The information is not meant for planning an individual therapy! All medications have side effects and contraindications, so it is necessary to discuss with your personal doctor, what would be a recommendation for your individual case!

What is altitude sickness?

At higher altitudes, your body has to cope with lower air pressure and lower oxygen levels. The lower levels of oxygen lead to higher pressure in the pulmonary arteries and higher blood flow in the brain which later can progress through complicated physiological processes, that are also not completely understood, to a swelling (edema) in the brain and lung tissues.

Depending on individual factors, altitude sickness can also occur under 3500 meters (some studies show, that at rapid ascend to 2500 meters it can occur in 20% of the people and at rapid ascend to 3000 in 40% of the individuals, and there were even documented cases at 1500-200 meters). But it becomes a significant and common problem first at 3000-3500 meters and above. The slightest form is acute mountain illness (AMS), which can progress into high-altitude pulmonary edema (HAPE) or into high-altitude cerebral edema (HACE), which is life-threatening.

What are the sypmtoms?

Headache is the earliest and most typical sign of AMS. The further symptoms could be: feeling overtired, having difficulties sleeping, dizziness, shortness of breath, and nausea. Vomiting can also occur, but it can also already be a sign of further complications as it can indicate an increased pressure in the head, which is a sign of brain edema!

If neurological symptoms appear,  like difficulties in coordination, inability to think or concentrate, and confusion, these are clear signs, that your brain starts to swell up and that you develop a HACE. Remember that in this condition the ability to think clearly and make sane decisions is also compromised! Mountaineers in such conditions would often not realize that they have to turn around and try to descend, which often has fatal results.

The other serious complication of AMS is HAPE, which is in the earlier stage characterized by slighter difficulty to breathing and non-productive cough and in more serious cases causes productive cough, crackles over the lungs, serious difficulty breathing, low peripheral oxygen saturation levels and it can rapidly progress to death.

How to prevent AMS?

Acclimatisation is key and that takes time. Over 3000 meters the maximum recommended elevation change is neat 300 meters/day. This should be the maximum difference between the altitudes where you sleep. The rule is often summarised as: “Climb high and sleep low”. So you can make a bigger altitude movement during the day if you afterward descend and sleep at an altitude that is around 300 meters higher than your previous sleeping place.

What happens when you are moving around by bus or car high altitude roads in the Himalayas or in the Andean mountains? These roads can confront your body with very drastic altitude changes within a couple of hours. For example, the Manali-Leh highway in India starts around 2000 meters, climbs through multiple mountain passes with the highest being 5300 meters, and descends to Leh at 3500 meters. So if you want to take such a journey without stopping and maybe even to sleep close to the mountain passes, you will have a pretty high probability of problems!

But what to do if you don’t have the opportunity to acclimatize properly? Let’s take again my example with the bus journey from Manali to Leh or even worse, flying from Delhi at 220 meters to Leh at 3500 meters. Well, that’s a risk and I would recommend (in case there are no contraindications present) taking Acetazolamide 125 mg every 12 hours to reduce the risk of AMS. For individuals, who have a history of HAPE, it can also be recommended to take prophilactically extended release Nifedipine 30 mg every 12 hours.

What to do if you notice symptoms?

If you experience only slight symptoms (headache. fatigue) it is enough if you provide yourself with sufficient fluid intake (dehydration worsens AMS!) and descend. If symptoms of AMS are more expressed I would recommend to take also Azetazolamide 250 mg every 12 hours. But remember: the definitive therapy for AMS is descending! Taking medications and not descending will not be able to prevent further complications!

HACE (high-altitude cerebral edema) and HAPE (high-altitude pulmonary edema) are life-threatening medical emergencies, that need immediate evacuation, oxygen supplements, and medication.

For HACE the treatment of choice is dexamethasone, that can be administered orally, as intramuscular injection or intravenously.  It is recommended to start with an initial 8 mg dosis that should be followed by 4 mg every 6 hours.

HAPE (high-altitude pulmmonary edema) is treated with nifedipine 30 mg extended release tablets every 12 hours.

What about traditional medicine?

In many high-altitude regions of the world, there are traditional ways how to deal with mountain sickness. At the moment there is no scientific evidence, that any of them would really work, so they are also not recommended. But as a cultural curiosity, it is interesting to mention these as well:

Mate de Coca: a tea made from Coca leaves that is used in the Andean region against altitude sickness

Rhodiola rosea (Golden root) and Gingko biloba: these plants are used in Chinese and Tibetan traditional medicine.