Altitude Sickness with Dr Jim Duff

Ascending in perfect conditions in the Karakoram, Pakistan | Tim Macartney-Snape
Ascending in perfect conditions in the Karakoram, Pakistan | Tim Macartney-Snape

Ascending to altitude is a great experience, the preparatory training, the challenge involved and of course those magnificent views. But spare a thought for your physiology that quietly undertakes numerous adjustments to keep you safe as you climb higher. If you take it easy and ascend slowly enough all should be well but push too hard, too high and too fast and your physiology will fail to acclimatise and high altitude illness develops. Altitude illness becomes common above 3000m and presents in the following three ways.

Acute Mountain Sickness (AMS)

AMS is reasonably common and can range from mild to severe. It is not life threatening (but left untreated it can become HACE, High Altitude Cerebral Edema) and presents with headaches plus one or more of these symptoms: nausea, loss of appetite or tiredness. The Lake Louise score is used to grade the severity of the AMS. If symptoms are mild then resting at the same, or a lower altitude till they disappear is the cure of choice. If symptoms are severe then descent is necessary.

Ascending Kyajo Ri with spectacular views of the Himalaya |  <i>Tim Macartney-Snape</i> All high altitude treks carry a Portable Altitude Chamber |  <i>Lachlan Gardiner</i> Approaching the summit of Cholo in perfect conditions, Khumbu region, Nepal |  <i>Soren Kruse Ledet</i>

High Altitude Cerebral Edema (HACE)

The headache is more severe and accompanied by signs of neurological disturbance such as increasing loss of coordination, reduced mental abilities and eventual loss of consciousness. The heel-to-toe walking and finger-nose tests are diagnostic aids.

High Altitude Pulmonary Edema (HAPE)

This can occur alone or along with AMS and/or HACE. Symptoms include increasing tiredness, a dry cough eventually producing frothy sputum and shortness of breath with an increased respiratory rate (check the normal rate on a well person for comparison).


HACE and HAPE can be fatal but are fortunately less common than AMS and the definitive treatment is immediate descent.


While all this may sound daunting, remember that you are walking or climbing out of our planet’s atmosphere and by the time you reach 4500m you are more than halfway to the breathable limit! If you think you or someone on your team are becoming ill, tell your leader immediately and do not ascend further with symptoms of altitude illness to prevent it from progressing to HAPE or HACE. A more detailed explanation of high altitude illness and its treatment can be found at


On all trips that take you to 4000 metres and above, World Expeditions carry a Portable Altitude Chamber (PAC) a lightweight hyperbaric chamber that can be easily carried by our porters. This assures you that when needed, we can quickly treat you for high altitude illness as an emergency. 


Dr. Jim Duff was an integral part of the World Expeditions team for 30 years, retiring from his role as our official medical consultant in September 2012.

altitude, climbing, expert tips, hiking, mountains

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<…> The company hired me as a co-leader for a few years and I then received first aid training by Dr. Jim Duff, KEEP and other Nepali doctors. I have now been leading groups as a trek leader since 2009 in the <…>

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