Altitude Sickness

Altitude sickness can occur at altitudes above 2000m and can affect anyone. The risk of altitude sickness is greatest with poor acclimatization (habituation), but very well acclimatized persons can also be affected.
Altitude sickness is caused by a lack of oxygen in the air: Hypobaric hypoxia. As you get higher in the atmosphere, the air pressure decreases and with it the number of particles of oxygen per liter of air. With every breath you take, you take in less oxygen than at sea level. In response to this, the body will create extra red blood cells: these transport oxygen to the other cells in the body.

This takes time: It takes a few days to climb a mountain like Mont Blanc (as a lowland resident) with a greatly reduced risk of altitude sickness. The motto here is usually: get as high as possible during the day and stay low overnight. This would speed up the process. It is important to drink plenty of water: the air in the mountains is often dry, physical activity is high and the production of extra red blood cells makes the blood thicker. Water is the best thinner for this.
Above 7500m, the body can no longer adapt and one will become increasingly tired: this is called the Zone of Death

Symptoms & forms of altitude sickness

Hoogteziekte treed in de meeste gevallen zeer acuut op, maar niet altijd even intens. Er zijn milde symptomen en ernstige symptomen. De milde symptomen bestaan uit slapeloosheid, verhoogde hartslag, verminderde eetrust en hoofdpijn. Tevens kan er misselijkheid, diarree en braken optreden. Dit hoeft echter niet. Dit noemen we Acute Mountain Sickness of “AMS”. Naarmate het zuurstoftekort zich verder opbouwt, verergeren de symptomen en kan AMS over

Altitude sickness occurs in most cases very acutely, but not always as intensely. There are mild symptoms and severe symptoms. The mild symptoms include insomnia, increased heart rate, decreased eating rest and headaches. Nausea, diarrhea and vomiting may also occur. However, this is not necessary. We call this Acute Mountain Sickness or “AMS”. As the oxygen deficiency builds up, symptoms worsen and AMS can progress to HACE: High Altitude Cerebral Edema. Or High Altitude Cerebral Edema. This is characterized by uncoordinated muscle movements (usually of the large muscles), also called Truncal Ataxia. Inflammatory reactions and possible other forms of edema also take place elsewhere in the body.
The greatest chance of developing AMS and HACE is by rapidly ascending (more than 500 meters per day) to altitudes between 4500 and 6000 meters. HACE hardly occurs below 4000 meters. Between 4200 and 5000 meters approximately 0.5-1% HACE develops (Luks, Swenson & Bärtsch, 2016).

Another type of altitude sickness is HAPE: High Altitude Pulmonary Edema, or pulmonary edema due to high altitude. This form of altitude sickness develops at a lower altitude than HACE: from 2500 m. It is usually preceded by Acute Mountain Sickness. Increasing shortness of breath and dry cough is an early sign. Coughing up red alveoli is a rather late sign.

HAPE affects a relatively large number of people: up to 7% of the population with a very rapid rise (one day) to 5000 meters.

Altitude sickness is extra dangerous in combination with frostbite. The thickening blood makes it more difficult to reach all parts of the body. This increases the risk of frostbite.


There is actually only 1 effective remedy for altitude sickness: descending (Luks AM, Swenson ER, Bärtsch P. Acute high-altitude sickness. Eur Respir Rev 2017;26: 160096 [] ). Drinking plenty of water can be relieving, as can taking certain medications. However, neither offer a structural solution and may increase the risk precisely because the symptoms are reduced.

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