Vamos Expeditions Adventure



As we get many questions about this from our travellers we decided to write a blogpost about what altitude sickness is, what the symptoms are, how it can be prevented by you and how it is treated.  If you are traveling higher then 2500 m.a.s.l. (8000ft.) it would be good to read this information and tell your companions about it. It can prevent a lot trouble for you.

Why does altitude sickness happen?

Altitude sickness, also called ´soroche´in South America, happens because there is so much less oxygen in the thinner air that you breathe when you are in the high mountains. It is not surprising that this can cause people to feel unwell.  Your body needs that oxygen to take it to your brain, muscles and organs.  To compensate that there is less oxygen in the air, your hart will pump faster and you will start to breathe faster to take in more oxygen.  This oxygen will be carried through your blood to keep your body functions working.  However how exactly this shortage of oxygen leads to altitude sickness is still not fully understood. Some scientists believe that it is due to swelling in the brain but the evidence for this hypothesis is not conclusive.

What are the causes of altitude sickness?

There are 2 things that certain make altitude sickness very likely:

  • Ascending faster than 500 m. per day, and
  • Exercising vigourously. 

Physically fit people are not protected – even Olympic athletes can get altitude sickness too.  There are many stories of fit and healthy people being badly limited by symptoms of altitude sickness, while their older companions have felt fine. If you have a previous history of suffering from altitude sickness, then you are probably more likely to get it again. Older people tend to get less acute mountain sickness – but this could be because they have more common sense and ascend less quickly.


How can I prevent altitude sickness?

Keep the following guidelines in mind when heading to high altitude:

  • Go up slowly.
  • Take it easy.
  • Acclimatise: give your body time to get used to the altitude. Take your siesta. Proper acclimatisation is the best defense against altitude sickness.
  • Avoid alcoholic drinks, tobacco and sleeping pills.   (even the day before you go up to higher altitudes)
  • Avoid heavy and greasy food.
  • Drink water, stay hydrated!    Because you breathe more, you automatically lose more liquid and you need to drink more.)
  • When possible try to have a good night rest the day before going to higher altitude.
  • People with heart conditions or high blood pressure should check with their doctor prior to high altitude travels.

If you keep this in mind you should be just fine 🙂  They body has an amazing ability to acclimatise to altitude, but it needs a bit of time. For example, it takes minimum one week to adapt to an altitude of 5000m.


What are the symptoms of altitude sickness?

Symptoms altitude sickness include:

  • headaches
  • nausea
  • vomiting
  • dizziness
  • lethargy
  • poor sleep
  • loss of appetite

At  they describe the symptoms as “very similar to a really bad hangover.”inca-trail-pass

Should I take medication to prevent altitude sickness?

Medication is also an option. Acetazolamide (diamox) is the most common type of “soroche pill.”  Further options exist, but always keep in mind that  they are no substitute for proper acclimatization.  Always consult your doctor before taking altitude sickness medication.  As with everything, many ´quack´treatments and untested herbal remedies are claimed to prevent mountain sickness. One should be cautious with them, they could make altitude sickness worse or have other dangerous side effects – many herbs are poisonous.  There is now good evidence [BMJ. 2004;328:797] that acetazolamide reduces symptoms of acute mountain sickness in trekkers, although it does have some unusual side-effects: it makes fizzy drinks taste funny in the mouth and it can make your hands and feet tingle.


Can I drink coca tea or chew coca leaves? 

If you travel to Peru or Bolivia you can drink the local coca tea, it’s everywhere available in the Andes, or chew coca leaves upon arrival at altitude and during your stay. While largely unproven scientifically, the locals swear by it.


What is the treatment for altitude sickness?

Successful prevention is obviously preferable to treatment.

In all cases, the best treatment is descent. If heading to a lower altitude isn´t an option, stay where you are and rest for a day or two. Acetazolamide (diamox) tablets can also help.  Whatever you do, don´t go any higher.  Pressure bags or oxygen gas can buy time.



The 3 forms of altitude sickness

There are three forms of altitude sickness:

1.) Mild altitude sickness or acute mountain sickness (AMS)

Mild altitude sickness is called acute mountain sickness (AMS) and quite similar to a hangover.  It causes headache, nausea and fatigue. This is very common. Some people are only slightly affected, others feel awful. However AMS is a mild condition of altitude sickness, it should be taken as a warning sign that you are at risk for one of the more serious forms of altitude sickness that can be fatal within hours.

2.) High altitude pulmonary oedema (HAPE)

Hape is a severe and dangerous build-up of fluid in the lungs that prevents the air spaces from opening up and filling with fresh air with each breath. When this happens this person becomes progressively more short on oxygen, which in turn worsens the build-up of fluid in the lungs. In this way, HAPE can be fatal within hours.

The two more severe forms of altitude sickness, HAPE and HACE, show similar, albeit heightened symptoms, sometimes with additional symptoms such as a severe cough, breathlessness at rest, blue lips or irrational behavior.

The most important treatment for HAPE is descent. Providing extra oxygen and/or raising the air pressure around the victim with a pressure bag can reverse the underlying process, lack of oxygen, but these measures are no subsitute however for rapid descent down the mountain. Some drugs can be helpful, but should only be used by trained doctors. For example Sildenafil, (Viagra), also opens up the blood vessels in the lung and may be a useful treatment for HAPE.  Drug treatment should only ever be used as a temporary measure; the best treatment is descent.

3.) High altitude cerebral oedema (HACE)

HACE is a build-up of fluid in the brain, a life-threatening condition that requires urgent action. HACE is thought to be a severe form of acute mountain sickness. A severe headache, vomiting and lethargy will progress to unsteadiness, confusion, drowsiness and ultimately coma. HACE can kill in only a few hours. A person with HACE will find it difficult to walk heel-to-toe in a straight line  (this is a useful test to perform in someone with severe symptoms of acute mountain sickness).  HACE should also be suspected if a companion starts to behave irrationally or bizarrely.

Factors that increase the risk of HACE are similar to those for acute mountain sickness and HAPE. The faster the rate of ascent and the higher the altitude, the more likely it is that HACE will develop. HACE is thought to occur mainly in trekkers or climbers who have ignored symptoms of acute mountain sickness and climbed higher rather than staying at the same altitude or descending.

Descent is again the most effective treatment of HACE and should not be delayed if HACE is suspected. A Gamow bag, or portable altitude chamber, can be used as a temporary measure and, if available, oxygen and a drug called dexamethasone should be given.


High Altitude Destinations in Peru

Altitude sickness won’t be an issue in towns and cities located along the coast and in the lowland jungle regions of Peru. In the highlands, however, you can soon find yourself at heights of 8,000 feet (2,500m) and above — the point at which altitude sickness can occur.

Here are some notable destinations located close to 8,000 feet or above (for a more complete list of altitudes, see Altitude Table for Peruvian Cities and Tourist Attractions):

Cerro de Pasco14,200 feet (4,330m)
Puno and Lake Titicaca12,500 feet (3,811m)
Cusco11,152 feet (3,399m)
Huancayo10,692 feet (3,259m)
Huaraz10,013 feet (3,052m)
Ollantaytambo9,160 feet (2,792m)
Ayacucho9,058 feet (2,761m)
Machu Picchu7,972 feet (2,430m)

Please help us to spread this information as widely as possible. Everyone who travels to high altitude should know this. Following these simple rules could prevent many problems for travellers in the mountains each year.



More information about AMS, HACE and HAPE can by found on the website of:

They also ask people how have had HAPE or HACE in the past to contact them for study purposes.

References: Hackett P and Roach RC. High altitude cerebral oedema. HAMB 2004; 5(2):136-146

by Kenneth Baillie, A.A. Roger Thompson, Matthew Bates , Annelies Hamerlinck.


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