What are the physical effects of altitude? / Where do I go to learn about altitude-related illnesses? [back to top] [FAQ contents][Mountaineering FAQ]

Good Places to Start

An Altitude Tutorial from the International Socieity for Mountain Medicine, 9/8/2001

Acclimatization and Illnesses from the Outdoor Action Guide to High Altitude, 7/7/1999

Going Higher : Oxygen Man and Mountains by Charles Houston

From: Brutus of Wyde, 3/9/2001

Initial adaptive responses to altitude include:

Hyperventilation (breathing fast)
Shortness of breath during exertion
Increased urination (altitude diuresis)
Changed breathing pattern at night
Awakening frequently at night
Weird dreams

Hyperventilation is a normal response to decreased partial pressure of Oxygen, and increases the Oxygen saturation of the blood.

Shortness of breath during exertion is a normal response as well, and in a non-AMS situation resolves quickly after exertion ceases. It results from the triggering of the physiological O2 "setpoint" due to increased oxygen demand during exertion.

Increased urination also occurs relatively quickly in response to increased altitude, and is a primary and longer-term tool in the body's acclimatization. Although the process is not fully understood, results from changes in body chemistry (Blood pH, buffering levels, Bicarbonate levels, and carbondioxide levels being the most obvious) and also possibly due to the adaptive response of increased hematocrit which provides more efficient gas exchange across the alveolar walls. NOTE: increased hematocrit [red blood cell concentration] is NOT the same as more red blood cells.

Changed breathing pattern [at night] is also a normal response, resulting from cyclic influence of both CO2 and O2 saturation setpoints.

Frequent awakening at night to urinate, and/or in the "breathless" phase of cyclic breathing, is a normal response to these normal adaptive mechanisms, and should not be considered a symptom of AMS.

From: Hal Murray, 8/14/1997

The best general audience book I've seen on altitude is: Going Higher Charles S. Houston, M.D. ISBN 0-316-37446-6 My copy says "Revised 1987" on the cover.

It's ~300 pages. It contains a lot of history and technical background. I don't see anything on long term issues. It's well written.

He has another book out. I haven't read it yet. High Altitude: Illness and Wellness ISBN 0-934802-72-6

It's 72 pages. It looks like a shorter (and updated?) version of the previous book. It has a few pages on CMS - Chronic Mountain Sickness. That appears to be a specific illness rather than a section discussing problems from long exposure to high altitude.

Now that I know what to look for, there are several hits for CMS in the index of Going Higher.

High Altitude has a further reading section that includes: High Altitude Physiology Edited by John B. West Van Nostrand Reinhold. 1981 and High Altitude Medicine and Physiology Michael P. Ward, James S. Milledge, and John B. West University of Pensylvania Press, 1989

Another book has just been published. (I was going to put in a plug anyway.) This is serious medicine rather than lightweight reading. High Altitude Medicine by Herb Hultgren, M.D.

I don't have the ISBN handy. It's self published and distributed out of his garage so that probably doesn't matter. It's >500 pages and $60 (plus shipping+tax).

I've only skimmed parts of it. I don't have a medical background but I can read most of it. (There isn't too much latin mumbo-jumbo.) It's good enough that I'll read it when I get (make?) time.

See also:

The High Altitude Medicine Guide
Altitude Sickness on DMOZ.org

Less Serious Effects/Issues

From: Sue Hopkins, 3/22/02

for the dry throat some people us glycerine type candies.

For the nose there is a nasal lubricant you can spray in (sort of like K-Y for the nose). Its supposed to be good. I have not used it mostly because it hasn't been that much of a problem for me.

From: Brutus of Wyde, 3/22/2002

Cough drops are standard equipment for me at altitude. My nose has worse problems than diamond-hard boogies... the tissues often dry to the point of nose bleeds. Vasoline works well, but is unlikely to be on hand. Chap stick or other similar lip balm is effective in a pinch, just be careful to not stick the chapstick tube up your nose before offering it to your partner.

From: Dave Condit, 12/22/1988

During the class, the instructors talk about evolved gas problems that we might experience. These problems can include gas trapped under fillings. If the dentist does not get all of the decay out before placing the filling, further decay may eventually produce a tiny pocket of gas. As one ascends, the gas expands causing pressure on the nerve. This can be quite painful and can also result in the filling popping off.

However, these days it is extremely rare. Modern dental x-rays can usually help a dentist to detect the decay. None of the instructors (who have seen many thousands of students go through the chamber) had ever seen this occur.

I wouldn't be too concerned about this. But if you have reason to suspect a potential problem, you might want to see a dentist before you fork out the big bucks & head off on some expedition.

From: Mike Yukish, 12/22/1998

The gas-under-the-filling problem most likely comes up in an explosive decompression situation, where you go from 10,000 feet to 25,000+ feet in seconds. Otherwise, the excess gas under the filling is absorbed by the body or slowly leaks out. I doubt you could hike that fast.

See also:

High Altitude Flatus Expulsion - stomach gas, 2/17/2002
contraceptive pill at altitude, 1/13/2000

At what altitude do altitude-related illnesses start to develop? [back to top] [FAQ contents][Mountaineering FAQ]

From: Ken Cline, 3/9/2001

Lowlanders show shortness of breath (and presumably impared athletic performance) here in Colorado at 1500m.

Here's what the High Altitude Medicine Guide has to say:

What is meant by high altitude? Some "formal" medical definitions:
- High Altitude: 1500 - 3500 m (5000 - 11500 ft)
- Very High Altitude: 3500 - 5500 m (11500 - 18000 ft)
- Extreme Altitude: above 5500 m

Practically speaking, however, we generally don't worry much about elevations below about 2500 m (8000 ft) since altitude illness rarely occurs lower than this. Acclimatization is the process of the body adjusting to the decreasing availability of oxygen. It is a slow process, taking place over a period of days.

From: David Ress, 3/23/1995

Altitude tolerance is a very individual attribute. It changes not only from individual from individual but can change in one person as they age. The only safe thing to do is to heed the symptoms, and descend if you have to.

From: George Bell, 3/9/1995

At what altitude does the average person begin to notice a difference in body function?

Well, most anyone will notice the difference even going to Denver from sea level (0' -> 5000'). Aerobic exercise will make you breathe harder, you may get more bloody noses, headaches, have trouble sleeping, etc. for several days.

When does it become serious?

As I understand it, the rule of thumb is that serious high altitude problems like HACE and HAPE are rare below 12,000'. Factors that work in one's favor for acclimatization are being in good shape and being born at a high elevation. It is also more important the elevation you are sleeping at rather than your peak elevation for the day. For example most people living in Denver who are in good shape have no altitude problems driving into the mountains, climbing a 14er and then returning to Denver for the night (ask Bob Broeking, he does this every Saturday and Sunday of the year judging from his trip reports :-).

Are there any "average" people in this case?

Yes, but you never know who they are. ;^]

How can I avoid developing altitude-related illnesses? [back to top] [FAQ contents][Mountaineering FAQ]

From: Ken Cline, 3/9/2001

The best prevention is to ascend slowly (over a period of days), drink plenty of water, avoid alcohol and other depressant drugs, take it easy when you reach your high elevation destination, and consider whether the drug diamox (acetazolamide) is appropriate for you.

From: Peter Green, 3/3/1994

You now know how you react, and can be careful. Ascend slowly (which may rule out some weekend warrior-ing), sleep low (and well), drink tons of water, don't over-exert (being in shape helps this happen), and descend RAPIDLY if symptoms are strong.

From: Jeff Stone, 8/19/1994

In A Guide to Trekking in Nepal (The Mountaineers, Seattle WA, 1985 [there may be a newer edition]), author Stephen Bezruchka includes a discussion of the symptoms, prevention, and treatment (DESCEND!) of the several kinds altitude sickness. A "must read" for anyone who travels at higher altitudes. Definitely become familiar with the observable symptoms in oneself and in one's travelling companions.

Among his recommendations for improving your tolerance of high altitude:

- Climb high, sleep low. Climb above your intended intended camping/sleeping place during the day but return there to sleep.

- Keep well hydrated. Drink 4 litres of water / day. You should urinate .5 - 1 liter / day of almost clear urine (equiv to waiting to pee until you're "full to bursting", twice a day).

- Eat lots of carbs, avoid excessive salt.

- Get plenty of rest; avoid over-exertion.

- Forced deep-breathing (without hyperventilating) can help.

From: Woody Schlom, 7/4/1996

I too have occasionally and seemingly randomly suffered from AMS (Acute Mountain Sickness). Almost every reference I found referred back to the same source for it's information. So I went to the source, which turned out to be carried in several local (So. Calif.) outfitter's shops. If you can't find it locally, you can probably mail-order it from REI. I bought mine at REI for $6.00 US. It's a rather small booklet with less than 80 pages.

MOUNTAIN SICKNESS, Prevention, Recognition and Treatment by Peter H. Hackett, M.D. Published by The American Alpine Club, Climber's Guide

Besides the recommendations in the book and drinking lots of water, I've had success with an old Sierra Club trick, EXTREME DEEP BREATHING.

From: Fwank Lichtenklitz, 10/3/2001

From: Review Articles, High Altitude Illness, Peter Hackett, MD and Robert C. Roach, Ph.D. New England Journal of Medicine, July 12, 2001

Highlights:

Gradual ascent is still the best strategy for AMS avoidance.

The notion that overhydration prevents AMS has no scientific basis.

From: Sue Hopkins, 6/11/2002 by email

What about hydration? Common wisdom says it's an important part of acclimatization. Is it true that scientific studies seem to say otherwise?

Dehydration causes headache as does altitude. altitude causes dehydration because you lose more water in the increased breathing. maintaining adequate hydration is important , but the value of over hydration which many people advocate has not been shown to be effective.

From: S. Deem, 9/20/1997

Good cardio makes it easier on you.

This is actually controversial. Although there is no doubt that being in good shape is essential for mountaineers, there is no evidence that aerobic fitness protects against AMS. In fact, some data suggests the opposite; long distance runners adapt less well to altitude, possibly because of reduced ventilatory drive.

Can I build up acclimatization over a period of time or acclimate ahead of time somehow? [back to top] [FAQ contents][Mountaineering FAQ]

From: Ken Cline, 3/9/2001

Do you think that daily running in normal atmosphere (few kms) could be helpful to get easier accustomed to high-altitude conditions?

No. Well trained athletes have just as much trouble with acclimitazation as anyone. Maybe more.

From: NOLS Wilderness First Aid, 1991

In general, the body becomes approximately 80 percent acclimatized after 10 days at altitude and approximately 95 percent acclimatized by six weeks. The respiratory rate peaks in about one week and then slowly decreases over the next few months, although it tends to remain higher than its normal rate at sea level. After 10 days, the heart rate starts to decrease.

When we descend, we begin losing our hard-won adaptations at approximately the same rate at which we gained them; 10 days after returning to sea level, we have lost 80 percent of our adaptations.

From: Sue Hopkins, 3/16/2001

I've wondered recently if going from sea level to altitude on the weekends helps with acclimatization or if you lose any gains you might have made in the intervening days.

The answer to theresa's question is that in part it does help. The breathing response when you go to altitude is your hypoxic ventilatiory response. It turns on faster and you breathe more (i.e. it is a greater response) if you have a previous exposure. How long does this effect last? Purists in the control of breathing field say you have to wait a year before studying someone's response after an altitude exposure to get rid of the effects of the previous exposure. We wait 3 months.

From: Hal Murray, 3/12/2001

My rule-of-thumb...

Going to the Sierra every other weekend is significantly better than every 3rd weekend. Every 3rd weekend is close to starting from scratch.

I suppose that going every weekend would be much better than every other weekend but I don't have any good data or rumors to back that up.

From: MadDog, 3/13/2001

I've talked to other people that would agree. It probably depends in part upon what your base elevation is, what the highest elevation you reach on your once every 2 or 3 week trip, how much time you spend at those higher altitudes and if you get much above your base altitude during climbs or training in between your trips to higher altitude. Sort of like looking at the altitude stress over time. If there's alot of contrast, then the time window between altitude stress could correlate with the difference in altitude.

From: Sue Hopkins, 12/3/2001

More trips, even short ones = better. There are measurable changes in chemoreceptor function (the cells that make you breathe in response to hypoxia) for months after an altitude exposure. While the acute blood chemistry part of acclimatization is gone within a few days you'll breathe more, earlier with a previous exposure in the last 2-3 months.

How can I sleep better at altitude? / Should I take sleeping pills? [back to top] [FAQ contents][Mountaineering FAQ]

From: MarkW, 12/3/2001

I have not suffered AMS but do suffer from being a light sleeper and especially so when I am excited about an alpine start. I take an herbal (Valerian root based) over the counter sleeping aid (forget the name--check the labels) and sleep alone in my tent/bivy sack. The sleep studies that I have read show that sleeping with a (noisy) partner yields less productive sleep even though you may not remember waking up.

From: Nate, 12/3/2001

Reaching for the drugs rather than dealing with the mental toil is, IMO, dulling the experience.

I rarely sleep a full night at the base of a big climb - I certainly didn't claim to. In fact, I find it empowering to know that I can toss and turn a full night without a wink of sleep and still perform well the next day. It's happened to me twice, and everything turned out okay. I value those experiences and emotions too much to drug them away.

From: Maohai Huang, 6/10/1998

if you can't sleep because of the altitude, and have time to acclimatize, don't take pills. if you don't have time to acclimatize and you know you can go down quickly after the climb, take pills so you can have good rest. if you can't sleep becasue the tent flaps too loudly in wind, use ear plugs. but be sure you can wake up on time for early starts.

From: Brutus of Wyde, 6/9/1998

I used Diphenhydramine Hydrochloride (sp?) aka Benadryl aka Sleep-eze aka Nytol at Genet Basin, and noted a distinct increase in altitude-associated problems the next day. I discontinued use for the remainder of the expedition.

On a long stay on a big peak like Denali, where complete acclimatization is the best recipe for success, I feel DPH is contraindicated due to its CNS depressant effects including the afore- mentioned respiratory response.

However, when one good night's sleep is more critical for success, such as in a fast, light round trip from sea level to 5.10 climbing at 14,000 feet, I still use approx. 50 mg of the stuff when spending the night between 8,000 and 11,000 feet.

From: Michael Riches, 10/2/2001

I agree, eat and drink and acclimatize. I do Ambien, occasionally and it has "always" left me hung over, in the morning. Any type of sleeping pill does. I think it affects performance, I've found that even trying to sleep leaves me in better shape, in the morning, then after taking something. I've never tried Diamox and won't speculate. I occasionally have problems sleeping at altitude, but I have never really suffered because of it. I guess if you were doing something that took a couple of weeks to climb, not being able to sleep would be a serious problem, but losing one or even two nights sleep has never seriously affected my abilities to climb...I'm tired from the time I leave the trailhead till I get back home, to me, after a certain point, it all seems the same, anyway...

See also:

Should I take Diamox? on Tradgirl

Should I take Diamox? [back to top] [FAQ contents][Mountaineering FAQ]

From: Sue Hopkins, 12/3/2001

Its a prescription drug and should be individually prescribed, Guides should not be just handing it out.

From: Greg Todd, 10/5/1999

No one else has mentioned diamox, because 99% of the climbers are against using it. I guess I'm in the 1% who think it may be ok in limited application. It's a diuretic, used princiipally I think for treatment of glaucoma since it reduces pressure of certain blood vessels on the eyeball. (Again, sketchy understanding here.) Anyway, my mother takes it for glaucoma, and has for several years, with no side effects other than the usual tingling in the fingertips and sometimes toes. So I'm a little less predisposed against it, since it seems to be ok in my family gene pool. And maybe I liked to play with drugs as a younger person...

I have found, using it on several occasions, that I can use a really very small dose (like 1/4 of a pill size my mother might take, morning and night), one or two days before going to altitude. It seems to do something for me --- I start to pee more than usual, and somehow that flushing seems to be "good" for changing the pH balance in your blood. Then I stop the day I get to altitude, or one day after, on the theory that I don't need an aritificial kicker to get my blood changing over anymore.

On the other other hand, maybe this is all a placebo effect.... (and maybe the diamox has been rotting out my brain since taking it, which might explain a number of things going on lately!)

From: Gary Hine, 7/8/1996

The other day I had to take my son to the doctor for attention to an infected cut. While there, I mentioned our upcoming trip to the mountains an asked about a Diamox prescription. To my surprise (since we live at only 500 ft ASL) this doctor was *very* knowledgable about altitude sickness and its treatment since he vacations in Colorado. He takes Diamox and Dexamethasone when he goes to the mountains. He gave me prescriptions for both.

Ask your doctor as both are prescription only, at least in the US.

From: Sue Hopkins, 1/18/2000

In order to understand how Diamox works an explanation of the changes in breathing at altitude (ventilatory acclimatization) are in order first. When you are exposed to either altitude or hypoxia the first response is an increase in breathing. This response, termed the hypoxic ventilatory response, or HVR, is mediated by the effects of hypoxia on receptors located on the carotid arteries called the carotid bodies. These carotid bodies respond to 3 things in the blood: hypoxia, acid pH, and an increase in carbon dioxide. Increased oxygen, alkaline pH, and decreased carbon dioxide have an inhibitory effect on the carotid bodies. The secondary effect of this increased breathing is a reduction of the carbon dioxide in the blood because you are now hyperventilating, and with a lowered carbon dioxide level comes an alkaline pH. So the net result is that you have two conflicting inputs on the carotid bodies: hypoxia saying "breath more" and alkaline pH and low CO2 saying "breath less". (You also have receptors in your brain , which respond to CO2 and pH changes, which are also inhibited). These responses to hypoxia happen within minutes. Later on the kidney get into the act and over a period of a few days restore the blood pH to normal by excreting bicarbonate (HCO3-). Studies have shown a relationship between with a brisk HVR, performance at altitude and relative resistance to AMS. (If you want the ref. just send me a mail). Interestingly, endurance trained athletes tend to have a blunted HVR and may be more susceptible to AMS (controversial point).

Diamox (acetazolamide) is drug that is an inhibitor of carbonic anhydrase. Carbonic anhydrase catalyses the reaction H+ + HCO3- <--> H2CO3 <--> H2O + CO2. Inhibition of carbonic anhydrase results in the retention of hydrogen ions by the kidney and the excretion of sodium and HCO3- in the urine (hence its effect as a diuretic) . The important effect for AMS is that it creates a more acidic blood pH. This in turn removes some "breath less" influences at both the carotid bodies and the receptors in the brain. Diamox thus increases ventilation and therefore oxygenation. Diamox has been shown to be beneficial in the preventing or reducing the symptoms of AMS in susceptible individuals. Diamox does nothing to aid diffusion of oxygen, contrary to what has been suggested by other posters.

Diamox should be prescribed by a physician. Although serious side effects are rare, there are some bad ones such as allergies and bone marrow depression. It should also be noted that most researchers in the field now feel that AMS is a mild form of High Altitude Cerebral Edema, so you should keep this in mind when you or one of you partners has symptoms of AMS and treat it with respect.

Standard Cautionary Note: Drugs such as Diamox are not a substitute for proper acclimatization and good judgment.

There is an excellent discussion of AMS and Diamox in High Altitude Medicine by Herb Hultgren 1997, Published by Hultgren Publications. Herb Hultgren who was one of the pioneers of high altitude medicine and physiology, died in 1997 at the age of 80.

From: William Woody, 12/5/1994

Essential Lesson: DIAMOX IS NOT THE ANSWER TO HIGH ALTITUDE ILLNESS. Diamox can help. It is a good thing. But it is no substitute for drinking huge amounts of water, acclimating slowly, being in good shape (no one knows if this helps, but it is not likely to hurt), and paying good attention to your body. If you do all of these things and feel that taking Diamox would help your body deal with altitude, take it and you may improve your chances of avoiding trouble. But do NOT believe that just taking Diamox will eliminate the possibility of getting edema. If all that you do to protect your body from the effects of altitude is take a drug, be aware that there is a possibility that you can die a slow and painful death, drowning in your own phlegm and blood with only a monster headache to console you. Diamox DOES help, but remember the essential lesson: DIAMOX IS NOT THE ANSWER TO HIGH ALTITUDE ILLNESS. To believe so strongly in this is to not take altitude seriously and to risk ugliness.

From: Kobus Barnard, 12/1/1994

What diamox can do for you is to help you sleep through an ocasional bad night. It is to be used in conjunction with proper acclimatization. Let's not imply otherwise.

From: Dan Tressler, 10/2/2001

Diamox treats the oxygen problems that interfere with sleep. It doesn't always induce sleep if other factors are operating, such as anxiety, excitement etc. If you go in the direction of a sedative to induce sleep, consider asking your doc for something that will be out of your system by morning. Ambien is a good choice. Little risk of a hangover.

From: Sue Hopkins, 12/3/2001

Diamox abolishes the periodic breathing associated with altitude, and raises oxygen saturation during sleep which can be the cause of poor sleep at altitude. It does this by making your blood more acidic and reducing the effect on blood pH that hypoxia induced hyperventilation casues. I've posted on this a couple of times and you'll find it in google I suspect.

Diamox is a pretty safe drug but there are people who should not take diamox, such as those with allegies to sulfa drugs and a few other and like all drugs there can be rare serious side effects. For this reason I suggest you get a prescription from an MD and not just whip across to mexico and get some or get some from a friend.

The more you go up and down the better it will be. Even short exposures to moderate altitudes will help, and of course acclimatization. Dingus is right Diamox makes beer taste bad, but since I can't drink at altitude at all (and a blender party at 12,500 is a truely ugly thing BTW) that doesn't affect me. YMMV. There is a recent (in the last year) good article by peter hackett on the diamox, and a really bad one (biased) by some brits, discussing effective doses which reccommends far too high a dose.

Like Rockrat I don't like the idea of sedatives, but lots of people use them. Some preliminary evidence that Ginko Biloba may help too, but has some risk of blood thinning as well. ASA would be a prescription drug if it was invented today, many people have GI side effects from it, and Im not sure it would do much. Tums should not help at all.

I'm alway amazed at how little sleep I can get before climbing and still feel good after the inital horror of first the alpine start is over.

Work is a different story, I go back and forth from sea level to 12.5 over a period of 8 hours, several times during the summer. Diamox helps me sleep and helps my AMS.

As usual YMMV, and you should never take medical advice over the internet :)

From: Robert Lindner, 12/3/2001

If you have problems with altitude, rather take your time and acclimatize properly, listen to your body. Medication like Diamox should be kept for emergency situations. A good dose of Aspirin (500mg) before going to bed usually helps me with sleeping in altitude, dampens as well slight headache, if there is any. If headache and even nausea are dominating, go down.

From: Nate, 12/3/2001

Just my negative opinion, but drugs like this should be no substitute for learning about how your individual body functions at altitude - and dealing with it. Taking these drugs, IMO, will leave you alienated from what it really takes to operate and be comfortable in the alpine environment.

From: Steven Eckert, 7/10/1996

Diamox is an unnecessary crutch.

Not if you've got the body chemistry that I do. (I used to toss my lunch at about 13000 in the Sierra Nevada pretty regularly, and with Diamox I was OK at 22800 on Aconcagua, 21800 on Mera, and 18600 on Elbrus.)

Next some *nitwit* will say that anyone climbing with glasses or contact lenses is cheating. If you have asthma, then you can damn well stay home (no medicine for YOU). Then the hearing aids will have to go and we can use sign language to signal the belayer. Finally, we'll take away all the cars so only those who can WALK to the mountain can climb it. Then it will be FAIR!

Sheesh. There's a difference between a drug that counteracts symptoms and a drug that boosts "normal" performance. For those lucky enough to not be bothered by altitude, Diamox does nothing. Steroids and uppers are not in the same category as Diamox and antihistamines.

From: Steve LaSala, 7/9/1996

I am reluctant to mask the symptoms of AMS with drugs because:

A) I know my body is under stress, and trying to tell me to rest and allow it to adjust to the new environment.

B) AMS may progress to more serious conditions. Pulmonary or cerebral oedema can be fatal overnight. I don't want to die because I shut off the warning signs with drugs and went even higher. That's like turning off the smoke alarm and going back to sleep.

If the headache is mild, normal headache remedies will allow you to sleep, at the cost of thinning your blood. If the headache is severe, GET DOWN IMMEDIATELY.

The most complete reference on this subject that I know of is "Going Higher: The Story of Man and Altitude"

From: Ken Cline, 7/17/1996

I can't find any suggestion that Diamox "masks the symptoms of AMS" in this book. Some benefits of Diamox are listed in the section, Effects of Acetazolamide on Exercise at Extreme Altitude:

The study [Hackett, et al. 1985] ... illustrates what happens in climbers who acclimatize at altitudes of 4000-6000 m and then climb to extreme altitudes exceeding 7000 m. It reveals that even at these great elevations benefits in the form of PREVENTION of acute mountain sickness, FASTER ACCLIMITIZATION, IMPROVED VENTILATION at rest, and BETTER SLEEP are to be gained from the administration of acetazolamide.

The Altitude Illness Clinical Guide For Physicians web page specifically states that Diamox "does not cover up any symptoms".

There are side effects, and controversy as to whether Diamox impairs athletic performance. I am not recommending use of this drug, just responding to what I see as misinformation.

From: Sue Hopkins, 6/11/2002 by email

Its doesn't mask the symptoms, but it does nothing for HAPE. To me bad AMS is message that your body needs more time. You may treat your AMS with diamox but if you continue pushing hard and don't take into account that warning message you could get hit with something worse.

Will taking XYZ [ginkgo biloba, Viagra, antacids, etc.] help me to avoid altitude-related illnesses? [back to top] [FAQ contents][Mountaineering FAQ]

From: Sue Hopkins, 3/16/2001

Just saw two abstracts that suggest it (note: refers to ginko biloba) might work well (ramdomized double blind placebo controlled etc etc). I don't think of it as an alternative to Diamox, as I believe the proposed mechanism of action is different.

From: Anne in NYC, 12/3/2001

Once upon a time, I had terrible problems sleeping above 14,000 feet. Went days on treks without any sleep. Became unhappy with that situation. So next time I found myself with a pounding headache at altitude (the most common cause of my sleeplessness and discomfort) I took small (half a tab) doses of Diamox along with Advil before hitting the thermarest. Seemed to work well most of the time, but not always. Last summer, in preparation for a trip to Ladakh, where we would be flying from sea level to 11,500 feet, I took Ginko Biloba (the rec. dose escapes me at the moment) every day for the three weeks prior to arriving at altitude. I have never felt better or slept better in the mountains. I never needed any Diamox, even at camp at 18,000 feet. My travel companions (non Ginko-ites) had a real rough time upon arriving in Leh (even though one of them regularly lives at 7,800 feet), and took longer than I did to acclimatise. Conclusions? I'll take Ginko again, see if it really works, but I'll have the advil and Diamox (not to mention the Dex) ready if I need it. It's difficult enough moving around in the mountains. I'm old and need my zzzzzzs.

From: Fwank Lichtenklitz, 10/3/2001

From: Review Articles, High Altitude Illness, Peter Hackett, MD and Robert C. Roach, Ph.D. New England Journal of Medicine, July 12, 2001

Highlights:

In two controlled trials, Ginkgo biloba (80mg-120mg orally twice daily) prevented AMS during a gradual ascent to 15,000ft and was 50% effective in an abrupt ascent to 12,500ft. Prophylactic aspirin (325mg every four hours totaling three doses) reduced the incidence of headache from 50% to 7%.

From: Sue Hopkins, 6/11/2002 by email

Would you agree that taking antacids to help with acclimatization is a myth and not actually helpful?

Yes. If anything it should be harmful. Hypoxia leads to Hyperventilation leads to alkaline blood ph which decreases hyperventilation and reduces response to hypoxia. diamox makes the blood more acidic so hypoxia induced hyperventilation is greater and blood oxygen levels are higher. enough antacid to make any physiological difference would be in the wrong direction eg make the blood more alkaline.

From: Brutus of Wyde, 12/16/1995

Bottom line: Be very cautious about modifying your blood pH intentionally unless you know what you are doing, particularly when at altitude.

From: Michael Riches, 12/3/2001

Learning your limits and learning to read your body will always be the best advice. There is a time and a place for every drug on the market (and some that ain't...), but mixing distance from the nearest emergency room and speculation on what effect this or that chemical has on the body (especially at altitude...) can cause serious financial difficulties for your surviving relatives...Caution is advised.

See also:

Ginko Biloba for the prevention of AMS from the High Altitude Medicine Guide, 9/21/2000
Viagra as a prophylactic against high altitude sickness, 5/15/2002
EPO and High Altitude - using erythropoieten to prevent altitude sickness, 7/26/2001
Rolaids for Altitude symptoms?, 12/13/1995
altitude sickness FYI - using Tums to prevent altitude illness, 12/31/1994

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