High mountain ranges such as the Himalaya and Andes offer some of the most spectacular hiking opportunities on the planet. That being said, walking at high altitude brings with it certain risks, the most common of which is altitude sickness, known as acute mountain sickness (AMS). The dangers of AMS are very real, and it is a sickness that is almost entirely preventable, so long as some basic precautions are followed before and during your trek.

What is Altitude Sickness? 
  • Altitude sickness is the name given to the collection of symptoms that can occur when a person ascends too quickly at altitude.
  • Why does it happen? As altitude increases, atmospheric pressure decreases. As a result, less oxygen is available to the body’s tissues, which in turn means that the heart and lungs need to work overtime in order to compensate. If a person has ascended at such a rate that their body has not had sufficient time to acclimatize to the change in atmospheric conditions, altitude sickness may result.
  • Initial symptoms of AMS include headache, dizziness, nausea, shortness of breath, difficulty sleeping and extreme lethargy.
  • Advanced or severe symptoms include rapid pulse, irrational behaviour, loss of balance and coordination, severe headache, vomiting and persistent cough.
Prevention of Altitude Sickness  

The key is to acclimatize gradually. Keep in mind that there is no universal standard by which each and every hiker can gauge their tolerance to high altitude conditions. Everyone acclimatizes at different rates. If you take the necessary precautions and listen to your body, chances are you will be fine.

If you fly directly into a high altitude, be sure to take it easy for the first few days. Gradually increase your exercise workload. Factor in some touristy activities that involve walking. Going straight from the airport to the start of your trek is potentially putting yourself at risk of AMS.


From the time you arrive at altitude drink at least 3 litres of water per day. When you hit the trail, drink even more. The air is drier and thinner at altitude, however, due to cooler temperatures many make the mistake of not drinking enough water.

As the initial symptoms of AMS are similar to those of dehydration, people often assume they have AMS when in actual fact they are simply dehydrated. Either way, keep drinking. You will feel better for it. A good indicator as to whether or not you are sufficiently hydrated is your urine. The clearer the better.

Note that both alcohol and caffeine increase dehydration. Limit your intake of both when hiking at high altitudes.  This particularly holds true during the first few days of your hike.

Ascend Gradually  

Don’t overexert in the initial stages of your hike. Pace yourself. Aim at becoming progressively stronger as the trek continues. Think about being the tortoise rather than the hare.

Climb High, Sleep Low  

Climb high, sleep low is the strategy by which you sleep at a lower elevation to which you have ascended during the day. Which is why we have acclimatization treks that help you in the long run.


In regards to the use of Diamox as a prophylactic for mild symptoms of AMS, I personally prefer the natural methods described above. Consult your doctor if you are considering the use of Diamox or any other drug whilst trekking at altitude or give our office a call and we will tell you what we find is best (064)6644181 or email info@patfalvey.com.


If mild AMS symptoms occur:

  • Don’t ascend any higher.
  • Drink lots of water (at least 3 litres per day).
  • If necessary, take a couple of ibuprofen or paracetamol for a headache.
  • Rest until symptoms have subsided, which could take two to three days. it should be ok to start ascending again.
  • Do so slowly and with awareness.

In case of severe AMS symptoms:

  • Descend immediately.
  • Seek medical attention ASAP.
  • Note that if your symptoms are severe, you are beyond the point at which Diamox or any other medication can provide relief. your only option is to descend.

If you do not look after yourself and take the precautions mentioned above you may develop more serious forms of altitude sickness. Such as when fluid accumulates in the lungs (High-Altitude Pulmonary oedema or HAPE) and brain (High-Altitude Cerebral Oedema or HACE). Both these advanced forms of altitude sickness will cause death if you do not medical help.

The important thing to remember is to give yourself enough time for your heart and your lungs to expand and get used to the altitude. If you would like to know more about altitude or training for your next adventure, get in contact with us an email: info@patfalvey.com or call (064)6644181


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