Acute Mountain Sickness (AMS)

     Acute Mountain Sickness (AMS), often referred to as altitude sickness, is a fairly common and serious risk when trekking at high altitude in Nepal. AMS can develop at altitudes above 2000 meters (6500 ft), and the risk increases significantly as you ascend to higher altitudes.

     The early symptoms of AMS are headache, extreme fatigue, and loss of appetite/nausea. Some people also experience shortness of breath while resting. AMS is a result of the excessive accumulation of fluid in certain parts of the body, specifically the brain and lungs. When mild symptoms occur you must stop immediately at the current altitude until the symptoms have gone away. If symptoms persist after you have rested for a day or two, you must descend to a lower altitude (300 – 500m/1000-1700 ft lower)

     Worsening symptoms of AMS including increasing tiredness, severe headache, vomiting, and loss of coordination.  These are the symptoms of the more severe case of AMS call High Altitude Cerebral Edema (HACE). HACE can lead to unconsciousness and death within 12 hours if the symptoms are ignored. Increasing shortness of breath, coughing, and tiredness are signs of High Altitude Pulmonary Edema (HAPE), which can also be rapidly fatal if ignored.

     A person suffering from AMS may not be thinking clearly and may have to be forced to descend.  A person with AMS should not be allowed to descend alone. They should descend to an altitude where they feel their symptoms improve (usually after 300 – 500 meters of descent). Always follow your trek guide’s advice about how to deal with AMS symptoms.

     If you experience any AMS symptoms but are unsure whether it is AMS, always err on the side of caution and stop ascending and consider descending to lower altitude.

     Medications are not a good substitute for proper acclimatization in reducing the risk of AMS. Acclimatization requires a planned, slow ascent of not more than 300 – 500m (1000-1700 ft) per day. If you are acclimatizing properly you can also consider taking Diamox to prevent or alleviate AMS symptoms.

     You should not plan to trek to high altitude (over 3000 meters) if you have heart disease, difficulty breathing at sea level, or are pregnant. Children may be more susceptible to AMS, and because they may not be able to describe their symptoms should be watched very closely.

      Good physical conditioning does not prevent AMS, and persons who have not experienced AMS at high altitudes in the past may still develop symptoms on subsequent treks.

     Sleeping pills, sedatives and alcohol should not be used at high altitudes as they tend to decrease breathing and can lead to AMS. Drinking 3-4 liters of water or other fluids per day to avoid dehydration will help in the acclimatization process. It is also possible to use a Gamow bag to treat the effects of AMS. A Gamow bag, available at the Himalayan Rescue Association’s outposts in Periche (Everest) and Manang (Annapurna), simulates the air pressure of low altitude.

     While it is possible to employ helicopter rescue in case of serious AMS symptoms you should not rely on this, or wait for a helicopter if you experience AMS. Your first recourse should be to descend to lower altitude. However, because it may become necessary to call in a helicopter for evacuation, you should have an insurance policy in effect that covers this (very expensive) service. The helicopter service company requires a financial guarantee to implement a rescue so having this is essential if you are planning to trek at high altitudes, especially at or above 5000m/16,000 ft.

Key facts about AMS:

  • Anyone is susceptible to AMS, regardless of physical fitness or previous high altitude experience.
  • AMS can be deadly so act immediately at the first sign of any symptoms.
  • AMS can start to occur at altitudes as low as 2500 meters (8000 ft)

You can also read more about AMS at this professional site dedicated to the subject:

Altitude Comments

Of the main fears of trekking, especially in the Everest region, is the altitude and the problem of AMS (Acute Mountain Sickness).

The reason I was nervous about this is that there seems to be no pattern as to whom it affects. It does not depend upon the fitness of the trekker or on how many times that person has been to altitudes in the past. This seemingly random process worried me that it would prevent me from fulfilling my ambition of reaching Gokyo Ri and Everest Base Camp.

The best way to avoid the illness, or to reduce your chances of suffering from it, is to ascend gradually building in rest days to the schedule. One group I met was forced to descend after they ascended too quickly and had to abort their attempt for EBC. I was certainly glad that we had taken our ascent slowly and had an acclimitisation day in Namche.

The most common symptom of altitude sickness is a headache. In fact around 4000m it is almost universal to have one. Mine was a very dull and mild headache, not causing any concern for me as I knew to expect one. I would just pop some paracetamol and it cleared overnight. The headache is caused by the body pumping more blood to the head in order to give the brain the oxygen it is used to having at lower altitudes. Therefore deep breathing can help to alleviate it and this perhaps explains why my headache cleared overnight (compounded by the fact that my body became used to the altitude over time).

I also drank plenty of water. As you are exercising in sometimes cold conditions it can slip the mind not do drink. But not only will it help with any headache but it will defend you against the serious problem of dehydration. I aimed to drink at least 3-4 litres a day.

The only other mild symptom you may experience is a loss of appetite. Luckily I was not affected by this and found myself being called upon the finish the others meals – a role I delighted in.

You are rightly advised, if the symptoms progress into a more serious headache, dizziness and nausea, not to ascend any further; if the conditions becomes even more serious you should descend immediately and never alone. It can be a serious threat and so groups should always err on the side of caution. But for the most part it shouldn’t put your trek in jeopardy in any way.

Items To Consider For a Trek

I understand that there are copious amounts of advice for what to bring on a trek, but the truth is that you can never have enough advice. I hope to include here some items that you might not have considered bringing on a trek with you, but things I either revelled in having or rued in their absence.

Up in the high regions you won’t be eating much meat. Firstly it is so difficult to trek it up there and secondly on is recommended not to order it as the length of time it has taken to get there and/or the cooking may be suspect. But with meat as your main source of protein in the Western diet you may find that you lack protein for your time during the trek; with your muscles requiring protein to maintain strength (particularly important as you spend whole days walking) you’ll need to find another source of protein. So other than eating eggs for every meal you’ll find yourself lacking in choices on how to fill up on protein. Therefore you may want to consider bringing protein supplements or protein bars along with you to keep up these levels.

Another suggestion, and I strongly recommend this, is chocolate. For two reasons: firstly chocolate is a perfect way to provide you with fast-releasing energy – a boost for when you most need it (during a long slog up hill!) But not only does it give you energy, it provides a great morale boost too. A mental, psychological boost to defeat those ascents. Though the tea houses all stock industrial amounts of Snickers and Mars, unsurprisingly it is vastly expensive having been carried up by Sherpas. So I brought out plenty of my personal favourite (Cadbury’s Dairy Milk of course) to keep me stocked up.

Though it may sound too much like an unnecessary comfort during a trek, my group and I found ourselves craving for soya sauce. We’d often be having veggie fried rice or noodles and finding that soya sauce is a luxury up high and we were not able to have any. Though the food is plentiful and well-cooked it can be a little bland for our much-seasoned tastebuds. So soya sauce, or something similar, may just provide that extra something to your meals to make them truly delicious.

I found myself lamenting the lack of footwear I had brought. I only had my walking boots and flip-flops and so I would strongly advise to bring another pair of closed shoes for the tea houses. Your walking boots may get sweaty, wet, muddy or dusty during the day and flip-flops may not be warm enough for the evenings, so a pair of trainers would work very well.

I trekked in February, which was early and well before peak-season. Though we skipped any crowds we had the elements to battle with instead. With most of the path covered with snow (often compacted by others) I found the extra grips for my boots to be very useful. They were strap-on mini spikes whilst others wore mini-crampons. They helped immensely and I struggles to see how I would have managed without them on some sections, thus if you are planning a trek outside the main-season times I would consider taking some form of extra grip.

And finally for when you get bored of your group’s rubbish jokes or you are alone for a period, a book is second to none for occupying your attention. If you’d like to get an appropriate read for the Himalayas an accessible mountaineering book would be a good choice. I was glued to the riveting ‘Into Thin Air’ by Jon Krakeur.

So these are my recommendations having just completed a trek, though many you could survive without!