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Expedition Medicine

Page Type: Article

Object Title: Expedition Medicine

Activities: Mountaineering


Page By: markhallam

Created/Edited: Oct 31, 2010 / Jan 6, 2013

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NOTE: Originally posted November 2010 this article has been updated December 2012 - and again,6th January 2013. Much of the text has been revised, based on some recent personal experience. A new section has been added on non-standard or borderline treatments of high altitude illnesses and the section on Frostbite completely revised. Numerous new links have been incorporated and finally an Acknowledgements section has been added

This article is suitable for small groups, travelling light into the greater mountain ranges or other remote mountain areas. It is particularly aimed at trekkers or climbers, intending to go to altitudes of less than 7000 metres – and on straight forward routes, where there is some risk of illness but not great risk of physical injury.

Much in this article still holds true for the higher mountains, so it may still be worth a read if you are off to tackle one of the eight thousanders – or an unclimbed face on a remote Andean peak. But on such as these, risk of illness and physical injury is very much greater and you may be advised to have a seasoned expedition doctor in the party – who has current experience of trauma management as well as altitude awareness.

The article is on expedition medicine, but it is intended to be interesting as well as useful to non-medics especially. Many light weight parties go to altitude or to remote areas without having a doctor or nurse in the party. It is to be hoped that this article would provide a basic guide to some of the medical hazards which are possible – and to treatments which at the least may prevent the trip being spoiled for some or all of the party, but at most could save a life.

Whilst particularly aimed at non-medics, this article could also be of use to medical professionals acting as ‘expedition medic’ for the first time – and interested in a simple overview from which to make a start on their planning. Medics and others already knowledgeable and experienced in expeditions to altitude will be familiar with what is written here – but may well have comments on some of the opinions I have ventured, where medical consensus is unclear.

Particularly in the sections on altitude and altitude illness, I have kept to factual information and treatment principles as endorsed by a wide body of current medical opinion. In response to some of the feedback to date details on both controversial and developing treatments are now included. Some references are included for those who would like to go into more depth. Altitude illness has been very well researched now by generations of expedition doctors and scientists since the pioneers of the early 1950’s. There is a good deal to read if you have a mind to! The new links will add further scope here.

For other ailments there is even more scope for varied opinion. For example, on the subject of treatment of infections, no one antibiotic provides perfect cover or is perfectly safe. We are talking light weight expeditions – and most likely all the medical needs and contingencies would have to be carried in a first aid kit smaller than a doctor’s medical bag. With limited space in mind I have tried to select medications which have more than one possible purpose. For example: the antibiotic Clarithromycin can be used to treat chest, sinus, dental and skin infections; the steroid Dexamethasone is an essential to treat High Altitude Cerebral Edema (HACE) – but I have also suggested its use to treat allergic conditions, although normally a different steroid would be used. I have also tried to keep to medications which are as safe as possible for as many as possible – as far as is possible! Finally, I have tried to keep to medications which for the most have dose regimens of less than three times per day.

Qualification to write this article:

Aconcagua 2011 TR
Summit of Aconcagua 6962m, 4pm 17th February 2011
I am a medical practitioner with 30 years experience of both mountains and medicine. My medical background is varied, but my principle qualification is in General Practice. At the current time I am working as a General Practitioner with special interests in Substance Misuse and Viral Hepatitis.

I have been on four expeditions to the Himalayas, one ‘trekking’ and the other three climbing expeditions. On those I have spent more than three weeks of my life living at over 6000m and on one occasion reached nearly 7000m. I was expedition doctor on all of the trips – and gained experience treating members of the party as well as indigenous population of the countries I visited. All of this experience was back in the 1980’s.

But then in 2011 I returned to high altitude, this time to the Andes, where I made a solo ascent of Aconcagua 6962m. I wrote this article partly to revise my own altitude knowledge in preparation for the Aconcagua trip – and I have now updated it, in part based on what worked well/what didn’t work well on that trip.


Expeditions are hazardous. Going to even modest altitude on an ‘easy’ route carries risk of serious illness and even death. Any treatments suggested here keep to current medical consensus where possible but no treatment or advice eliminates all risk. Where medical consensus is unclear or divided, I offer my own personal opinion as a doctor with some recently updated practical experience. Individuals without medical experience should go and discuss use of any medications recommended here with their own doctor, preferably one who has knowledge on high altitude. I would especially advise this for those with pre-existing medical conditions, special circumstances such as pregnancy – or if responsible for young children.

Finally, few medical treatments can be 100% guaranteed to work. Hopefully treatments suggested here are likely to work, but failures can and do occur. The only branch of medicine I have worked in where drugs did what it said on the tin every time was anaesthesiology – there is no arguing with such as sodium pentothal for example. But whilst these drugs always worked, once in a while they also threw up an unexpected and even serious reaction. Each and every one of the drugs I have listed in this article can have adverse effects. Where an adverse effect is common or especially notable then it is mentioned. But much detail goes beyond the scope of this article. So if you plan to carry any drugs I have suggested then I would reiterate: do go and discuss with your doctor – as well as looking up more detailed information.


Prevention is way better than cure in most instances – or failing that, then at least some advance planning. There are a number of important issues to address before setting foot on the aeroplane:
Be fully insured for whatever you are planning to do. Make sure repatriation is included as well as cover for whatever rescue is possible, medical expenses etc. If you have a pre-existing medical condition you should disclose it, as well as discussing with your family physician.
Sort out any necessary immunisations well in advance. Check into your local travel clinic – or look on-line to find what you need (new links added at end). You may need antimalarials as well as vaccinations.
Be as fit as possible. Worth checking in with a fitness instructor at the local gym and sorting out a program which includes endurance cardiovascular training but also weights – especially if you are older and thereby more prone to injury. If you plan to carry 30kg on your back then some training should include this.
Make sure any footwear is broken in – although you don’t really break in plastic double boots, they break you in. Treat yourself to a toe nail ‘manicure’ last thing before you leave, cutting all nails as short as possible – but make sure you are versed in how to cut nails without setting yourself up for an in-growing toe nail (cut big toe nails near straight across, avoiding trimming corners back).
Be well versed in expedition medicine (so read this article!) – And make sure you and your party is provided for; for personal needs as well as minor or major medical emergencies.
See your dentist - allowing plenty of time to get any necessary work done well before you leave. If you have any uncertainty then read Joe Tasker’s account of his Dunagiri expedition with Dick Renshaw, in ‘Savage Arena’. A tooth abscess nearly put paid to the climb before so much as setting foot on the mountain – and caused him a week of misery and painful penicillin injections from a kindly Indian Army medic.
Try out your expedition food before you depart. My recent experiences have reminded me just how hard it is to predict what will tempt a jaded high altitude palate, but it is worth finding out whether your state of the art high altitude FD rations have any unfortunate effects (e.g. gas!).
If you have athletes foot (tinea pedis) and/or crotch rot (tinea cruris) then get it treated well in advance of going on a trip. Frequent users of gymnasium showers will be at risk of both. The fungi involved with these minor skin infections just love the sort of environment to be found in a sweaty pair of double plastics – or salopettes. The worst case of tinea cruris I have ever seen was in a companion on an expedition who ignored a minor itch – and ended up with sore pealing skin half way down his thighs. The day was saved with the chance finding of a tube of antifungal cream at an abandoned camp at 5500m. Note: if you have athletes foot, get your toe-nails checked: if infected these take several months of oral antifungal tablets to treat – but if untreated will ‘seed’ further outbreaks of tinea pedis.
Expedition Medicine Article
TrainFX – Danny, fitness instructor at my local gym


Expedition Medicine Article
The team en route to Broad Peak in 1987

For most, getting to the greater ranges involves air travel. It would be possible to base an entire article on this alone, but I will just focus on a few issues which impact on health – but especially on the ability to arrive at the destination in as clear headed a state as possible. Jet-lag is hardly conducive to efficient functioning – and arrival is often associated with the need to plunge straight into complicated organisational tasks to be dealt with in the minimum time, before getting on the road to the mountains. And it is important to get things right. It is no good getting to base camp and then finding you have left the matches behind or miscalculated on the funds needed to pay off a now justifiably irate bunch of porters.
• Flights leaving in the evening are more conducive to being able to get some sleep before arrival at destination.
• Avoid alcohol during the flight if you want to function at the other end. It is true that a drink in the air is worth two on the ground. And this principle translates into the size of the hangover you may have to contend with whilst trying to make sure you have enough currency to pay the mule man or calculate the number of bottles of white gas you need to purchase to stock camp one.
• Aside from changing time zones and lack of sleep, dehydration plays a major part in degrading performance after a long flight – one of the reasons why alcohol is not a good idea. As on the mountain, there is a need to drink more than is necessary at sea level – so frequent water or juice on the flight is advisable. Naturally, caffeinated drinks such as tea or coffee are a bad idea if you want to sleep.
• Eat, but don’t over eat.
• Some people resort to sleeping tablets on a long flight. I personally wouldn’t – the quality of sleep afforded is poor and most impair mental functioning for some considerable time – even after they appear to have ‘worn off’.
• One final point: on long haul flights there is a risk of Deep Vein Thrombosis (DVT: blood clots in the leg veins) due to being immobile for a long time. This risk would be considerably higher for a high altitude climber returning from a trip. Due to high altitude polycythaemia (thickening of the blood as an adaption to altitude) there is a much higher chance of a blood clot forming, with potentially serious results. Personally I’d take half an aspirin tablet a day, starting a few days before flying, and which slightly reduces clotting power of the blood. During awake times on the flight; go for short walks if possible or at least ‘wriggle toes’ at intervals. Someone with additional DVT risk factors (e.g. past history of same or of serious leg injury etc) – could consider wearing anti-embolic stockings.
In summary, get as much sleep as you can, drink lots of water or juice – and stay off booze, sleepers and caffeine. Have the odd light snack, wriggle your toes at intervals – and take the occasional stroll up the cabin.


The approach for most expeditions may well involve a long overland journey, initially by road and later on foot. There can be a few health traps for the unwary, especially in developing countries.
• Try to adapt to local time as quickly as you can i.e. be awake, active and eat during the day and go to bed at night, even if it is difficult to sleep then.
• In a hot climate there is the need to drink more water.
• If water is suspect then either treat it (see below under ‘diarrhoea’) or buy bottled where you can... but check the seal – sometimes you may be sold a ‘branded’ water bottle which has simply been refilled from the nearest tap or dodgy water source. Don’t even clean your teeth in suspect water.
• But do clean and look after your teeth. Aside from the unpleasantness for any tent companion if you don’t, the last thing you need is a dental problem fifty miles from the road head.
• If you want to avoid diarrhoea then avoid salads, fruit unless peeled by yourself, ice cubes and food that hasn’t been thoroughly cooked. In some places it may be safest to go ‘veggie’- but still important that the food is cooked. Consider using your own eating utensils – or using your own (clean) fingers.
• Clean hands thoroughly after going to the toilet or before eating – or cleaning teeth. Could be worth carrying a few pocket sized antiseptic hand gel packs – but alcohol gel doesn’t inactivate some viruses and cannot replace thorough hand washing with soap and water (where the water source is suspect use both). Keep finger nails short.
• When on foot treat any river crossings with respect. Ensure at least someone in the party is experienced at these – and don’t hesitate to delay continuing a journey to wait until early morning, when river levels are often at the lowest. 
Expedition Medicine Article
Overland travel in the Himalayas – Himachel Pradesh, India, in 1983
Expedition Medicine Article
Camp at Skardu en route to Broad Peak 1987
Karakorum river crossing
River crossing en route to Broad Peak in 1987


This section gives an overview of a few basic principles for the safe ascent of a big mountain - before more the more detailed discussions in later sections.

The rules are comparatively simple and yet so easy to break – especially if you have been focussed on ‘the summit’ for the past two years of planning and anticipation. But if the intention is to come back alive and sporting the correct number of fingers and toes then there are a few general principles…
Push yourself in training but try not to overdo it whilst acclimatising. This may be easier said than done when acclimatisation is likely to coincide with the need to carry loads to set up and stock high camps. Nonetheless overexertion should be avoided in the early stages of a climb.
You must allow time to acclimatise. If you don’t then at best you will end up demoralised and miss the summit, at worst you may end up dead. Above 3000m the current literature suggests that however high you go on an acclimatisation foray; try not to raise your sleeping height by much more than 300-500m per day – on average. So if Camp One is 600m higher than Base then minimum would be to do an up & back to that height before going up and spending a night. If Camp One were 900m higher then two ‘up & backs’ before spending the night… etc. Additionally also add in a rest day every third day, where you stay at whatever height you have reached.
Don’t go to bed on a headache. Don’t even think of taking one higher up the mountain! If you do your up & back(s) and later return to spend the night with a headache then I quite like the advice given by R.J.Secor in his climbing guides: “if I have a headache then I drink a litre of water… if after an hour I still have a headache, I drink another litre of water whilst descending…” This is good, safe advice, although personally, I may also try a minor painkiller (see Acute Mountain Sickness, below).
Drink plenty of water but don’t overdo it. Dehydration makes you feel crap, saps energy and is dangerous – but so does over-hydration. Be guided by your urine output: if you are ‘going’ regularly every few hours and your urine is normal pale straw colour then you are drinking enough; if you are passing dark coloured urine once per day, you are not. Conversely, if you are passing large volumes of what looks like plain water every 20 minutes you may be drinking too much!
Food is your energy source and is very important. You may be expending 6000+ calories per day exerting at high altitude. Paradoxically you may not feel hungry and you may even feel nauseated. But if you don’t keep topping up with food as your energy source then you will run out of energy – and crash or succumb to the cold – or both. If energy is fading, or you are cold – eat something, preferably complex carbohydrate, which gives a sustained release of energy. If you have cold hands or feet consider the need to eat as well as attending to insulation.
Don’t ignore cold hands or feet. It may be tempting to, since they hurt for a while and then the hurting stops – as they go numb. If they go numb and stay numb then you are heading for frostbite. 
Expedition Medicine Article
Broad Peak 8047m, Karakorum Himalaya
Expedition Medicine Article
Menthosa 6440m, Indian Himalaya


Aconcagua 2011 TR
Aconcagua 6962m, highest summit in the Andes
This section overlaps with an excellent article by txmountaineer 7th January 2008. He has produced an excellent piece talking about altitude from a highly scientific perspective – and he has included some great illustrations that my SP expertise hasn’t caught up with yet. Here is the link to that article:

Hi Altitude

There is another good SP article by florida frank on pressure & altitude, posted 1st September 2010:

Pressure & Altitude

Although the atmosphere extends up to well over 100 kilometres, most of it is concentrated in the bottom 10km (10,000m) – and atmospheric pressure drops off rapidly within this layer. By 5000m it is just 50% of sea level value. By around the height of Aconcagua at 7000m, pressure is down to 40%. By 9000m, or just higher than Everest, the pressure has fallen to less than 30%. These percentages equate to the available oxygen – so that 30% of atmospheric pressure means only 30% of sea level oxygen available for breathing. Without some form of adaptation the human body cannot survive on such low oxygen levels. A rapid ascent from sea level to 9000m would result in unconsciousness within minutes – and death soon after.


It is quite extraordinary that over a few days to a few weeks the human body can adapt to surviving at extreme altitudes. The process is known as acclimatisation. Many individuals have now summited Everest (8848m) without supplementary oxygen following a period of acclimatisation of 4-6 weeks. Nonetheless, there are limitations: it is not possible to adapt to permanent habitation above around 5000m. Miners in the Andes working at over 5500m learned from bitter experience to descend to below 5000m to sleep – and did better doing this, despite the daily trek back up to altitude each day. It is possible for an acclimatised person to spend periods of a few weeks between 5-6000m – but inevitably health will eventually deteriorate to the point that survival becomes threatened. The higher you go above these altitudes; the more rapid this deterioration. Above 8000m the limit may be a few hours to a few days for most people – before risking deterioration to the point of endangering ability to be able to descend. In 1999 Babu Chiri Sherpa spent an extraordinary 21 hours camped on top of Everest and survived to tell the tale – but there have been accounts of ‘extra’ nights spent at lesser heights, to ‘recover’ from a tough summit day, which have resulted in debility to a level that descent became impossible.

A number of adaptations occur to enable the human body to tolerate the low oxygen levels of high altitude. At the start of the process and within a very short period both heart and breathing rate increase – thus taking more oxygen in and moving it around more quickly. Within hours, urine output increases as the body sheds extra water – in effect enabling the blood to become more concentrated – and thus carrying a higher concentration of oxygen. This is just a temporary adaptation. In the long term the body achieves the same effect, not by losing vital water, but by increasing the number of red blood cells. And changes occur in the haemoglobin inside the red blood cells, improving oxygen delivery still further. As acclimatisation progresses the heart rate at a given height may gradually fall back down towards normal sea level values. The breathing rate however will remain high. And the process is far from perfect. Even in fully acclimatised individuals oxygen saturation becomes progressively less with increasing altitude.

A WORD OF WARNING: the increase of red blood cells increases oxygen delivery to the tissues, but the price paid is that the blood consequently becomes thicker and more likely to clot. With prolonged periods at very high altitudes, such as on 8000m peaks, there is a significant risk of deep vein thrombosis and even stroke – and a daily small dose of aspirin may be advisable to off-set the risk – along with avoidance of dehydration. Even on lesser mountains of around 6000m, significant thickening of the blood can occur within as short a time frame as two weeks. Anybody with any additional risk of DVT or stroke should consider aspirin under these circumstances – including on the flight home (see above). If you are uncertain about your personal risk factors then discuss with your doctor who is best placed to advise you. The sort of dose of aspirin appropriate to reduce clotting is of the order of 75-150mg per day ( ¼ – ½ a standard aspirin tablet).

Oxygen saturation:

It is possible to measure personal oxygen saturation levels using a small easily portable device known as a pulse oximeter. Such devices can be purchased for the equivalent of 80 Euros or less, run off a couple of AAA batteries and take up much less space than a mobile phone. To obtain a reading you simply clasp the little unit over a (warm) finger end and press the ‘go’ button – and within seconds the tiny screen will show both oxygen saturation and pulse rate. It is by no means essential to carry a pulse oximeter, to go to altitude. A ‘good’ reading does not guarantee immunity from altitude illness – although it may be fairly reassuring. Conversely, a ‘bad’ reading doesn’t necessarily mean you are in trouble. Either way, it is important to interpret the reading in association with any actual symptoms – and – preferably in association with a series of previous readings so ‘the normal’ is known for a given individual. For example:

The morning after summiting Aconcagua and after a 2nd night at 6000m, I felt a bit rough. I had no headache, wasn’t nauseated – I just felt rough. So I checked my O2 sat and it was 79% - and normal for that elevation is 77%. Previous readings had shown me that I