Acute Mountain Sickness (AMS) or Altitude Sickness – What is it and what you need to know?

Updated: Apr 27, 2018



If you’re planning to trek in the Himalayas, (or anywhere above 2500m) — it’s important to have a good understanding of altitude sickness. AMS poses a danger to everyone at these altitudes and can be fatal. Not all people know that it can be managed right with planning & preparation.We have guides with extensive local knowledge and years of experience who can help you mitigate the changes of AMS.


What is Altitude Sickness?


At high altitude, there is less available oxygen so your heart and lungs have to work harder, even at rest. Add the strenuous day of climbing a mountain trail and your body is under serious strain. As you go higher, this effect becomes increasingly severe.


Your body needs time to adapt as you go up and this is called ‘acclimatising’. If you ascend faster than your body acclimatizes, you will develop what’s called the AMS.


Early/mild symptoms

A headache (often worse when bending over or lying down), plus one or more of the following symptoms:

  • Weak & Dizzy

  • Loss of appetite, nausea

  • Insomnia, disturbed sleep & frequent waking

These early symptoms can also look like dehydration. It’s critical that you keep hydrated, protected from the sun and pace yourself, so you don’t mask AMS symptoms.


If untreated, then mild AMS can progress to cerebral edema or pulmonary edema. Both can be fatal and it is critical that you treat the early symptoms.


How to prevent AMS?

You will need to ascend at a safe rate and make sure the itinerary is designed by an approved operator. The itinerary should allow for adjustments to be made in case one or more of the group does not acclimatize adequately.



What do the experts say about ascending rate in the mountains?


Above 2500m, sleep no higher than 300m (10,00ft) above the previous night and have a rest day every third day up to 3500m (11,500 ft)

Above 3500m, only go up to 150m (500ft) per day with a rest day every three days


Preventative measures

  • Walk at a steady pace, with plenty breaks

  • Drink enough – total upto 3-4 litre incl tea/soups etc

  • Avoid sedative drugs & alcohol

  • Remember the symptoms – listen to your body and keep an eye on your fellow trekkers

  • Talk to the guide and follow their instructions

If you develop any AMS symptoms, you must speak up. The Buddha Odyssey trek guides are trained professionals and take its stance on AMS seriously. Always remember, if you know the risks, symptoms, and treatments then you can plan for a safe trek and it will be the experience of a lifetime!


Consult your doctor about trekking at altitude. If you take any medications, be sure to check how they may interact with altitude medication (e.g. Diamox) in case you need to take any. Be sure to advise us about any medications you take.

© Nepal Adventures, Canberra, Australia