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Home > Altitude: Information, prevention, advice

| Altitude: Information, prevention, advice |

During your journey, you may stay some hours or some days in altitude (up 2.500 meters). These informations are intended to you.


Cause of the acute mountain sickness

At altitude the atmospheric pressure decreases: there is less oxygen available for the organism. The oxygen quantity available at 3000 meters is equivalent to two thirds of the quantity available at sea level. At 5000 meters it is equivalent to half the quanty at sea level.

The organism reacts to the lack of oxygen (also called hypoxia) by two ways.

immediate reaction

Acceleration of the ventilation frequency and of the heart rate, in order to catch more oxygen in the air and to transport it quicker to the organes. This reaction costs a lot to the organism in terms of energy, as it makes the respiratory muscles and the heart working more.

gradual reaction

The immediate reaction is replaced or completed by a more economical mechanism: the increase of the oxygen transporters quantity, which are the red blood cells. They take time to be fabricated and at least a week in altitude is necessary to see their quantity increasing. The ventilation frequency and the heart rate may then decrease without getting back to their original value.


Who is affected ?

It is considered that the altitude sickness (called "sorojche" in the Andes) affects approximately
  • 15% people from 2500 meters
  • 60 % people from 4000 meters
  • Everyone at high elevation (more than 5000 meters)

Like sea sickness, it may affect anybody. The age or the sex are not risk factors.


What are the symptoms ?

The reaction to the altitude depends of each one. In most cases the AMS is mild and can be seen by diverse disorders happening separately or in association with others, from the first hours staying in altitude.

  • headaches
  • feeling fatigue and sleepiness
  • breathing problems
  • sleeping disorders
  • dizziness and balance troubles
  • lack of appetite and stomach disorders
  • nauseas
  • irritability
  • decrease of urine quantity

These symptoms, usual and normals, generally disappear by themselves (or at least are largely mitigated) after few hours in altitude and taking analgesics (aspirin or paracetamol).

In some cases severe complication may occur: pulmonary edema (cough, spitting, blue lips, insufficiant breathing) or cerebral edema (acute headache not relieved by aspirin, vomiting, sight troubles, sometimes psychiatric problems).

It is then a case of extreme AMS and action must be taken immediately

  • by bringing the suffering person down to the lower elevation possible and as soon as possible
  • by imperatively consulting a specialized doctor

We observe approximately one case of severe crisis every two years (they generally happen as soon as the first days in altitude).

Our guides and assistants are trained to diagnose the edemas when they happen and to take the most suitable actions.


Before the departure

A physical training before a stay in altitude does not prevent the altitude sickness, but it is obviously recommendable: biking, swimming, hiking (if possible in altitude) would be a good preparation.

Consult your doctor for him to detect possible deficiency or affections. If possible consult a centre specialized in mountain health.

For a holiday including sport activities (trekking, andinism…) above 3000 meters, we will require you to fill a health form (to be loaded below): depending of the answers we will require a certificate written by a doctor and certifying you are able to practice sports in altitude.


The acclimatization is essential

To mitigate the AMS effects and limit the aggravation risks, two key rules are to be followed.

Start slowly

A week in altitude is generally enough for a good acclimatization. We particularly ensure that our programs start smoothly with activities and excursions requiring low effort in the first days, staying in proximity of aid centre in case of need and planning resting times.

Go up gradually

We recommend not to go up of more than 700 meters from a night to another when above 3500 meters. For example, leaving from 3500 meters, you may climb to a saddle at 4500 meters (+1000 m) under the condition that you sleep lower, for instance at 4000 meters, the elevation difference between this bivy and the previous one being then only of 500 meters. All our trekking and andinism programs are designed to follow this progressivity.


A few advise for you holiday

in the first days

  • particularly in the first 24 hours, try to keep your energy, walk slowly and breath well
  • do not do useless or inconsiderate physical efforts "to test yoursel", even when feeling very well (this may help the AMS to happen)

during a trek or a climb

  • avoid high efforts (giant steps, jumping, running…)
  • do not put yourself in overspeed (for example by competing with others)
  • to sleep well, when arriving to the bivy site, walk up 200 to 300 meters without backpack, stay there for an hour and walk down to the camp
  • in case of suffering (excepting the headaches when relieved by taking aspirin), you must stop walking up and have a rest
  • if the symptoms persist you must then get down of 300 to 400 meters and restart the climb the following day only if the symptoms have disappeared ; in the opposite case you must end the trek or the climb

always hydrate yourself abundantly

To avoid dehydratation (helped by the combination altitude + sun + effort), it is essential to drink abundantly (3 to 4 liters each day). It would be an opportunity to taste a "maté de coca" (coca leaves infusion, typical drink in the Andes), energizing and considered as an excellent way to mitigate the altitude effects.

During the treks and the climbs, you should make sure to drink mineral water or to purify the water from the streams, otherwise you might discover other inconveniences, particularly stomach problems.

always eat well

During your stay, and particularly during a trek or a climb

  • keep a balanced diet (vegetarians may have iron deficiency which slows the red blood cells production)
  • eat a hearty and complete breakfast
  • eat regularly: each day in the mountains, energizing snacks (cereal bars, dry fruits, sugars) are provided by our accompanying teams

For your first meal in altitude we recommend to eat light food and to not drink alcohol.

what medicines ?

If you are under treatment, ask advise to your doctor and he would tell the possible contraindications when in altitude, the precautions to follow, the symptoms to be careful of…

In case of headaches, prefer the aspirin (which fluidifies the blood) to the paracetamol.

Do not take somnifers as thet help the breathing stops during the sleep, worsening the hypoxia (lack of oxygen).

The Diamox® (acetazolamide) increases the respiratory response to the lack of oxygen.

We do not recommend to take it in prevention, it is well better to opt for a natural acclimatization by getting up gradually in altitude.

Note aslo that

  • the Diamox may cause unwanted effects (metabolism disturbances)
  • the Diamox is a diuretic which may help dehydratation
  • when taken in prevention, it makes the altitude related problems difficult to detect

It may however be useful to bring some, and we recommend to take it

  • in case of poor acclimatization to the altitude, particularly if headaches persist despite taking analgesics
  • in case of ascending too quickly
  • to treat peripheral edemas (face, hands or anckle swelling, important when waking up and decreasing in the day) without other signs of the AMS

do not refuse a diagnosis

If someone suffers in altitude, it should be diagnosised as the AMS until other evidence !

Do not simply think that a headache is caused by the fact of walking in the sun without hat, or that a vomiting is caused by the unfresh eggs eaten the day before…

The diagnosis may be upsetting for a well trained sportman or frustrating because it implies to end a trek or a climb.

But denying it may lead to a disaster.

It is essential to be honest with yourself and with the guides and assistants who lead the trek or the climb.

They have a great site experience and will be able to provide you with good advise and with first aid if necessary.

It belongs to them to take the decision to leave or not a member of the group continuing a trek or a climb.



The stay in altitude, and particularly practicing sports (trek, andinism…) in altitude is highly contraindicated for the person suffering from •              blood circulation deficiency

  • chronical respiratory deficiency
  • epilepsy
  • diseases requiring repetitive injections (for instance diabete mellitus type 1)
  • cardiac diseases non stabilized
  • some blood diseases

It is also contraindicated for the persons who had a neurosurgery, or for the persons who had suffered a cerebral or pulmonary edema in a previous stay in altitude.

The altitude stays are generally unsuitable to pregnant women and newborn children (less than 18 months old).

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