Altitude sickness

Much is written and published about altitude sickness a.k.a. acute mountain sickness (AMS) . If you read peoples’ travel logs you find almost everyone seems to get it in the khumbu. The secret is to avoid getting it in the first place by being sensible about acclimatization. Common sense would suggest that you just can’t go four thousand meters up in a day and expect to function normally on half the amount of inspired oxygen that you are used to at sea level.

A lot of people get symptoms and put them down to other things. You might have a group of trekkers all of whom have headache and breathlessness and don’t tell each other, putting their symptoms down to other things, until one of them becomes seriously ill. In fact, at altitudes over 3000 meters if you have a headache it is probably altitude sickness.


Headache, breathlessness at rest, insomnia, maybe vomiting maybe confusion all make up the syndrome.

Treatment is always to descend to a level where you didn’t have symptoms and wait until they have gone before you ascend again. If you keep going up with the early symptoms you can become so seriously ill that fatal brain and lung oedema (waterlogging) can occur. If that happens it may not be treatable. Brain oedema leads to progressive severe headache worse with coughing, straining and bending and leads on to confusion, coma and death. Lung oedema is accompanied by severe breathlessness and coughing up pink frothy spit. For treatment see below.

In most cases where there are mild symptoms that are not progressing it may be permissible to just stay at that altitude and take a rest day or stay put until the symptoms go but if the symptoms get worse you have to go down to your individual level where you improve. That altitude varies from person to person and occasion to occasion so it isn’t strictly predictable. Always play it safe.

Another good tip is to travel with someone who cares enough about you to help you get down to a lower altitude (a relative or close friend) as you might not be able to travel by yourself if the symptoms are severe. Often people travel in large groups run by trekking agencies and the individual trekkers have spent a lot of money on their trip and don’t want to risk losing their chance of missing their “trip of a lifetime”. Trekkers get left behind by such groups with serious consequences.

My son Alex and I found a British guy in exactly that state last time we were in Nepal and he was literally dying of AMS. He had no medication and was on his own with a porter who had no idea what to do. We managed to give him appropriate medication and got him to where he could fly back into the Kathmandu valley and he survived, but no thanks to the people he was trekking with who had just left him to get down in altitude by himself (porters and sherpas aren’t doctors and can’t be expected to fulfill a medical role!)


Prevention is better than cure! It takes time to acclimatize. If you race ahead at the start in a competitive fashion and spend a lot of time out of breath you are more likely to get AMS. It is probably related to overbreathing which makes the blood alkaline as you breathe away a lot of carbon dioxide in your breath. This sets the scene for you to keep sodium and water in your bloodstream and you get waterlogged. Walk very slowly when at altitude and try as far as is possible not to get out of breath. If you can walk any slower in the first few days you are going too fast!. I think this is why older people trekking at altitude are less likely to get AMS as they are less competitive than the youngsters and don’t see it as macho to get high quickly. Easy to say, but if you slow down then you ascend slower and your body acclimatises better. Drink lots of fluids. Everest mountaineers recommend 3 litres of fluid per day. On my last trip, we drank large amounts of lemon tea at each stop on the assumption that it is acidic and may help reduce the alkaline effects of overbreathing. Probably an anecdotal old wives tale but it worked for us!

The mainstay of medical treatment of the early mild symptoms is a drug called Diamox (acetazolomide). This is taken twice a day (opinions vary 125 mg-250 mg twice a day) and increases the rate of breathing and helps acclimatization at a biochemical level. It is a carbonic anhydrase inhibitor and amongst other things makes you pee a lot! It makes your blood slightly acidic and stimulates respiration. Breathing quicker at altitude tops up your oxygen levels and is an important part of acclimatization. It is useful both for treatment of the mild symptoms and to help you to acclimatize. It does not mask symptoms and if you feel better on it you are better. You can’t take this drug if you are allergic to sulonamides ( sulfa drugs) and you would have to use dexamethasone which has dangers all of it’s own vide infra.

If you have a headache and breathlessness and insomnia take a Diamox and don’t go any higher until the symptoms have gone completely. If the symptoms get worse descend in altitude. Since this will delay you, make sure you have enough time in hand planning your trek to have a couple of extra rest days if you need them. Generally when planning your trek, if you can, climb high but sleep low.

Dexamethasone (12 mg first dose then 4 mg four times a day) is useful for brain oedema. It is a powerful anti-inflammatory steroid that stabilizes membranes in the brain and reduces the ill effects of the waterlogging. It only gives temporary benefit but may buy time to get the patient down to a safe level of altitude. It is not a prophylactic agent that allows you to go on upwards despite recent research which has suggested it is useful. Id you take dexamethasone at altitude then stop it suddenly whilst still at altitude you will get much worse very fast.

The lung oedema can be treated by taking a drug called Nifedipine which reduces the load on the heart and improves breathing. A diuretic such as Lasix may be of value as might taking off a pint of blood but I guess you would have to be pretty desperate to do that up a mountain (opening a vein not an artery) and there is no guarantee that AMS responds to either.

The overriding advice is: get the patient down in altitude if the symptoms are progressive.

The advice on this link is worth gold: