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Travel health

09 July 2019

How to prevent acute mountain sickness?

When we think of our health for a trip, our eyes generally turn to the vaccination needed abroad. What vaccines do I need if I go to Cuba, Mexico or even Thailand?

We rarely ask ourselves the question of altitude sickness ! In countries like Peru, some mythical places culminate at high altitudes: Machu Picchu at 2430m, Cuzco at 3225m and even Lake Titicaca at 3812m. It is therefore important to prepare yourself so that mountain sickness does not spoil your trip !

Acute mountain sickness is a condition that can affect mountaineers, hikers, skiers and high-altitude travelers, typically above 2,000 meters.

Causes of altitude sickness


Atmospheric pressure decreases as altitude increases and the resulting decrease in oxygen partial pressure results in hypoxia.

Those taking a direct flight to a high-altitude destination, such as Cusco (Peru, 3225 m), La Paz (Bolivia, 3658 - 4018 m), Lhasa (Tibet, 3685 m), Leh (Ladakh , 3505 m) must undoubtedly take into account the possible occurrence of acute altitude sickness. The faster you climb to a higher altitude, the more likely you are to suffer acute mountain sickness.

You are at higher risk of contracting acute mountain sickness if:

  • You reside at sea level and go to altitude
  • Fast ascent
  • The length of stay (the longer you leave, the greater the risk)
  • The goal to reach at altitude
  • Previous history of acute mountain sickness
  • Age <50 years 
  • The intensity of physical effort
  • You have been drinking alcohol and other substances that can interfere with acclimation.
  • You have medical problems:  heart, nervous system or lungs.


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  • Acute hypoxia
  • AMS (acute mountain sickness)
  • HACE (high altitude cerebral edema)
  • HAPE (high altitude pulmonary edema)
  • Cerebrovascular syndromes
  • Peripheral edema
  • Retinopathy
  • Thromboembolism
  • Sleep disorders and periodic breathing
  • Pharyngitis and high altitude bronchitis
  • Exposure to ultraviolet rays and snow ophthalmia
  • Exacerbation of pre-existing diseases


In most cases, the symptoms are mild:


  • Difficulty sleeping
  • Dizziness
  • Tired
  • Headache
  • Loss of appetite
  • Nausea or vomiting
  • Fast pulse (heart rate)
  • Difficulty breathing on exertion
  • Decreased urinary urination


Contact a travel health professional, member of Travel Health Assist

Treatment of altitude sickness


Early diagnosis is important. Mountain sickness is easier to treat in the early stages.

The main treatment for all forms of mountain sickness is to descend as quickly and safely as possible at a lower altitude. You should not continue to ride if you have symptoms.

Extra oxygen should be administered if available.

People with acute mountain sickness may require hospitalization.

A drug called acetazolamide (Diamox) can be given to help you breathe better. It can also help reduce symptoms. This medicine can make you urinate more often. When taking this medication, be sure to drink plenty and do not drink alcohol. This medicine works best in prevention, ie before reaching a high altitude. (see your pharmacist or travel health nurse)

Most cases are mild and the symptoms improve rapidly when you descend from the mountain at a lower altitude.

Severe cases can lead to death due to lung problems or swelling of the brain, so called cerebral edema.

In remote areas, emergency evacuation may not be possible or treatment may be delayed. This can have a negative effect on the clinical outcome.

The clinical result depends on the speed of descent once the symptoms appear. Some people are more likely to have altitude sickness. The reaction depends on the sensitivity of the person.


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Possible complications (cerebral or pulmonary edema)


HAPE: ( Hight Altitude Pulmonary Edema)


The symptoms of pulmonary edema develop most often from acute mountain sickness.



  • Intense headaches resistant to treatment
  • Difficulty breathing
  • Insomnia
  • Loss of appetite
  • Weakness, nausea
  • Dizziness, vomiting and apathy



  • Intense respiratory distress
  • Blue lips (cyanosis: impaired oxygen uptake in the alveoli due to fluid accumulation at this location)
  • Presence of rales to auscultation of the lungs with crepitation and wheezing due to the accumulation of fluids in the pulmonary alveoli.


HACE: High Altitude Cerebral Edema


The evolution of a benign AMS to an HACE can be spread over a 12-hour period or over a period of 1 to 3 days, which is much more common.



  • headache (headache),
  • loss of coordination (ataxia),
  • deterioration of the general state (asthenia)
  • gradual decline in the level of consciousness.

This loss of consciousness is characterized by disorientation

  • memory loss
  • hallucinations
  • psychotic behavior

Altitude sickness and sleep apnea


Elevation may increase the frequency of central apnea, which may result in the development of PAH (Pulmonary Arterial Hypertension)

It is imperative that travelers continue this treatment.

Prophylaxis of acetazolamide (Diamox) to reduce the number of apneas should be considered (see with your pharmacist or health nurse travel)

Acute Mountain Disease / Generalized peripheral edema


The first visible signs are the peripheral edema that we find very easily:

  • at the level of the legs and especially ankles by the sign of "edema of Godet" (important mark on the skin),
  • at the wrist by the marks of the wristband of the watch,
  • at eye level, more swollen than usual in the morning (bags under the eyes)
  • at the level of the swollen face taking on a "Mongoloid" appearance,
  • a weight gain occurs,
  • the emission of urine decreases.

When to contact a health care professional


Getting off the mountain immediately is the safest way possible.

To learn more, consult a professional Health-Travel Travel Health Assits member

Prevention of mountain sickness


The keys to altitude sickness prevention include:

  • Clim the mountain gradually. The gradual ascent is the most important factor in the prevention of mountain sickness.
  • First stay a few days at an intermediate altitude (between 1500 m and 2500 m) before climbing higher.
  • The frequency of the heart (pulse) must remain less than 100 / minute at rest. During the day you can still climb higher to promote acclimatization.
  • Avoid intense efforts and alcohol during the first 24 hours spent at altitude.
  • Drink enough (the urine must remain clear!), Even if you are not thirsty, because the loss of water by breathing increases strongly in altitude
  • Stop for one or two days to rest every 600 meters (2,000 feet) of climb above 2,000 meters (8,000 feet).
  • Sleep at a lower altitude when possible.
  • Make sure you have the ability to descend quickly to a lower altitude, if necessary.
  • Learn to recognize early symptoms of mountain sickness.

If you plan to climb more than 3000 meters, you must carry enough oxygen for several days.

If you are considering an ascent, ask your pharmacist for medications that may help you.

If you have low levels of red blood cells (anemia), ask your doctor if it is safe to travel. Ask him if an iron supplement is right for you.

Anemia decreases the amount of oxygen in the blood. This makes you more likely to suffer from mountain sickness.

During the ascent:

  • Drink a lot of water
  • Avoid alcohol
  • Eat regular, high carbohydrate meals


Travelers with cardiovascular or pulmonary disease should seek the advice of their physician before going at altitude.


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When traveling, regardless of your destination or physical condition, a consultation with a trained health professional is expected at least 6 weeks before your departure.

Christine Dumontet RN 

President Dumontet CSV and Founder of Travel Health Assist