Friday, May 10, 2019

Diamox - The Wonder Drug?

Diamox is the trade name for a drug called Acetazolamide. This is a "altitude wonder drug" that many people take to increase the speed of their acclimatization. It is also a drug that some people put a little too much hope into instead of acclimitizing properly.

The reality is that Diamox is not a wonder drug. It is is a carbonic anhydrase inhibitor that is commonly used to treat glaucoma, epilepsy, hypertension, cystinuria, dural ectasia and of course, altitude sickness. The drug is designed to help your body make the chemical changes that it needs to make in order to function better at altitude.

We get a lot of questions about this drug from people who are planning a Denali climb or other high-altitude objective. But we also get them from people who are going to go on relatively low-altitude climbs.

Those who are climbing peaks that are less than 14,000 feet tall really shouldn't worry about any type of specialized drug to acclimatize. They should just take their time. Those who are climbing peaks that are between 14,000 and 16,000 feet should only take the drug if they've had problems in the past. And those climbing peaks that are 16,000 feet tall or more, should really see how their body reacts before filling it full of drugs.

The reason that we advise caution with this drug is that it has side-effects that can be difficult to deal with. Diamox is a diuretic. It causes you to urinate frequently. This, of course, can lead to dehydration, which is a contributing factor to altitude sickness. It can also cause a very unusual sensation in the fingers and toes. It feels like they have fallen asleep. This could be confusing or even scary in extremely cold environments.

Diamox - A Prophylactic?

Some climbers choose to take Diamox prophylactically, starting a few days before going to altitude. A percentage of climbers respond well to this, especially if they take between 125 milligrams (mg) to 500 mg per day before ascending rapidly to 10,000 feet or more.

What is rapidly? This is generally a fast one to two day ascent from sea level. Examples of rapid ascents might include Mount Rainier or Mount Whitney in two days...

Those who have a history of Acute Mountain Sickness (AMS) are urged to take Diamox prophylactically especially with plans for a rapid ascent or plans to ascend 2000 feet or more per day after reaching 10,000 feet.

Diamox forces the kidneys to excrete bicarbonate, the conjugate base of carbonic acid. The more bicarbonate excreted, the more acidic the blood gets. The more acidic the blood gets, the more that ventilation is stimulated. This will ultimately result in more oxygen in the blood.

Clearly the changes in the blood take time. It takes time for the body to catch up to your altitude. As such, Diamox cannot be seen as an immediate fix for AMS. If the symptoms are bad, then climbers are urged to immediately descend before the AMS devolves into a life-threatening cerebral or pulmonary edema.

When to Take Diamox

Many guides argue that the best time to take a drug like Diamox is right before bed. As I know that I don't tend to breathe as deeply at night as during the day, I will usually take Diamox before I go to bed when I'm at high camps on high altitude peaks.

On the one hand an evening dose of the drug may help you acclimatize better up high at night. It may also keep you from getting sick at night. But on the other, you are unlikely to sleep well due to the whole, "I have to pee every five minutes" thing.

Others feel that the morning is better because it doesn't interrupt your sleep.


There has been a lot of research over the last few years that indicate that Ginkgo Biloba may work extremely well in acclimatization. As this is easily attainable at health food stores and has few side effects in healthy people, it may be a much better alternative to Diamox.

On the other hand, those taking anticoagulants such as ibuprofen, aspirin, warfarin, or antidepressants should be wary of potentially dangerous side effects.

Altitude Research

Understanding altitude and its effects on the body is an extremely broad topic. This blog has only touched on the bare surface of the subject and indeed, only on the bare surface of the uses of Diamox. Those interested in learning more should check out Going Higher: Oxygen, Man and Mountains by Charles Houston or Altitude Illness: Prevention and Treatment by Stephen Bezruchka.

A Final Note

We are not doctors. We are climbers. And the advice here is just that, advice. All the information here is based on our experiences working at altitude and everyone's body reacts differently under such circumstances.

Diamox is a prescription drug. And it is extremely important that you get proper medical advice before self-medicating with any such drug. If you are on an expedition with a guide, it is also important to tell your guide whenever you take any drugs.

High altitude climbing is an awesome experience. Diamox is merely one tool that will help you to get up high. Another, and perhaps far more important tool, is to use good sense, good judgment and to acclimitize properly.

--Jason D. Martin


Cale Hoopes said...

Jason, great post! Just an FYI, I mixed 360mg of Gingko Biloba per day with 400mg of Ibuprofen on Denali and had unbelievable success in regards to my acclimatization. On an expedition of 5, as we checked our numbers, my oxygen level was always higher than the rest of my expedition - which when I went to 20k before, I struggled greatly without anything. I believe the Gingko Biloba really helps.

fkarcha said...

Sorry, which research are you pointing too?

Ginkgo not significantly different compared to placebo in double-blind study (n=487):

No evidence for Ginkgo efficacy vs. placebo in double blind study (n=57):

Source of Ginkgo may impact efficacy:

Unknown said...

When taking any supplement/medication to counter the effects of altitude the person has to ensure they have enough for the trip plus extra. You may weathered in for exteneded periods. The sudden removal of the medication/suppliment can cause rebound effects that can go right to life threatening very rapidly.

Jason Keck said...

Great post, I really appreciate your conservative guidelines for when to take Diamox. There are a few other caveats to taking this drug for altitude acclimatization that I would like to mention. First, just to reiterate the risk of dehydration is roughly double for every 4,000 feet of elevation and, as you stated, dehydration can exacerbate altitude sickness. Low doses (125 mg) may allow climbers to avoid this risk.

Another potential side effect of Diamox that nobody ever talks about is that its ability to increase blood acidity may stunt hematological acclimatization. High blood acidity is proven to reduce levels of EPO in the blood. Elite altitude training programs always incorporate controls to reduce lactic acid production for this reason.

Finally, there are a few studies that suggest though Diamox may reduce AMS, it may have a negative impact on athletic performance at high altitude.

I work for Alpine Performance Laboratories. Our company has recently developed a supplement that allows athletes to pre-acclimatize their bodies to high altitude. Our product is called Mountain Might and it is about to release in 2 weeks. Feel free to contact us through our website for free samples or to talk with our high altitude physiology experts.



Jason Keck said...

There are various studies that suggest Ginkgo Biloba does alleviate AMS. I do not have links to them, but they are available in the book Altitude Training and Athletic Performance by Randall Wilber.

Glen said...

Sadly, those promising early Ginkgo biloba findings have not been supported in newer better studies. Acetazolamide, in spite of its many shortcomings, appears to be still the best bet for those prone to the disease. Dexamethasone is also a possibility, particularly for those with a sulfa allergy preventing them from taking acetazolamide.

Glen said...

OK, I have to ask the obvious question. What is in Mountain Might that has been shown to be effective in published studies in reputable journals?

Jason Martin said...

Jason's post above is the first time I've personally heard of this option...