Should I take Diamox (Acetazolamide) for Kilimanjaro?

Uhuru Peak sign on top of Kilimanjaro with blue skiesJust like you, I did a lot of research prior to my Kilimanjaro climb to try and learn as much as possible about the experience and maximize my chances to successfully summit the mountain. It was surprisingly hard to find good information about whether climbers should take Diamox (which goes under the generic name Acetazolamide) as a preventive measure to minimize or even prevent altitude sickness that often occurs on Mount Kilimanjaro.

My short answer is that it is entirely up to you. I took it and I’m very glad I did. While I did still feel somewhat nauseous and have a slight headache at the summit, it was surprisingly mild compared to what I have experienced at much lower altitudes in the past. There are pros and cons to taking the medication to be sure, but I definitely recommend considering the option for anyone that is concerned about altitude sickness preventing them from a successful summit. You must have a doctor prescribe the medication, so be sure to consult them and be open about any existing conditions and other medications you take regularly.

Have you had altitude sickness before?

Anyone that has ever had moderate to severe altitude sickness will tell you – it is NOT fun. At best, you will feel less hungry and slightly grumpy. But if it hits you harder, you feel incredibly nauseous and very fatigued with a pounding headache. I have climbed Mt. Rainier near Seattle Washington twice. The first time I spent a couple of days at mid camp (around 10,000 feet). I felt great the whole time all the way up to near 14,000 feet and kept asking myself “why is everyone so worried about altitude sickness?”. I trained hard for the trip and figured that’s why I felt so much better than everyone else (spoiler alert: physical fitness will not prevent altitude sickness). Unfortunately, we got snowed out just below the peak, which is not uncommon (even in mid-July!) because the mountain (much like Kilimanjaro) creates its own weather.

But I got a second chance a month or so later. The guiding company told me I really didn’t need to do snow school since I had just done it a month prior. So I just drove from my house (near sea level), arrived at the trailhead and hoofed it up to mid-camp at 10,000 feet. When I got there, I remember thinking “huh, I’ve got a little headache. That’s strange”. Because we wanted to beat an oncoming weather system, we only rested a few hours before we headed out for the summit late that evening.

I didn’t feel great the next morning (who would after 3 hours of so-called sleep), but figured I’d start feeling better soon. I forced myself to eat some oatmeal for breakfast and we headed off. By the first break, I knew something was terribly wrong. I could barely force myself to eat half of a cliff bar. The following break I tried my best to try and vomit (to no avail). The next break I realized I was in the throws of altitude sickness and decided to press through it. The good news is that I did summit that day. But it was a bear. They estimate you burn about 6,000 calories on summit day. But I was only able to eat about 400 calories.

Once I got down the mountain, I was able to eat some food and within a few hours I was back to normal. But I promised myself that I would always do anything I can to avoid feeling that way again. Well, I wasn’t go to stop climbing mountains, but I would take every precaution possible like acclimatizing properly and even taking Diamox for larger mountains.

What is it like taking Diamox?

I believe Diamox effects people somewhat differently, but I will tell you about my experience (which seem to align with others I’ve spoken with that have taken it).

First things first: You need to start taking Diamox before you reach high elevations. It is not effective in curbing the symptoms after you already feel sick. So you should start taking it either before you take off on your Kilimanjaro trek or perhaps sometime on the first day. And you need to keep taking it every day while you are ascending. Do not stop taking it until you have completed your summit.

If your doctor agrees, I do recommend trying out Diamox before you travel to Africa just for 2 or 3 days. There are some side effects, and you’ll want to be aware of those before you fully commit to it on the mountain. I experience three main side effects:

  1. The first day or two you will pee more. Like, a lot more. There is some complex science behind this, but essentially your kidneys over-react when you first start taking Diamox, then start to balance themselves out. By day three, you are pretty much back to normal. So don’t forget to keep drinking water, especially those first couple of days.
  2. You may have a “bubbly/tingling” sensation. I call it “sparkle mouth”, but you might also feel it in your hands, feet and lips. It is not anything troublesome, but I was glad I knew about it during my ‘test run’ off the mountain. It’s a heck of a lot better than bad altitude sickness.
  3. Beer (or anything carbonated) will taste flat (and probably terrible). This one is not such a problem on the mountain (while the porters will bring you just about anything you want, beer is not on the menu while on the mountain!). Again, there is a bunch of science behind this side effect that has been dubbed the Champagne Blues . But if you are like me and enjoy a celebratory beer after a long journey, be sure you stop taking your Diamox right after you summit. It will be perfect timing for your post hike brew!

Be sure to tell your guide

Before your climb, your guide, assuming you picked a good one, will ask you lots of questions about your health, your workout regime (physical fitness) and any medications you take. Be sure to tell him that you plan to take Diamox. This is important for them to know as they keep track of your health during the health checks.

Myths and Controversy of Diamox

There are a lot of conflicting stories, claims and myths on the internet about the use of Diamox for the purposes of altitude sickness. These range from the “it doesn’t work” to “it's downright dangerous”. I can only speak from my own experience and research, but here is what I believe to be true.

It will not prevent acute mountain sickness

Taking Diamox will absolutely not prevent altitude sickness. Rather, it is meant to speed up the process of acclimatization. But do not fall under the misguided notion that if you take Diamox you can do a shorter trip and move up the mountain quickly. Rather, it will help your body as it goes higher and higher up the mountain. Particularly at nighttime where many people feel they struggle to breathe as they fall asleep as their body deals with the thinner air and less oxygen.

It does not dangerously “mask” symptoms of altitude sickness

Some guiding outfits have banned the use of Diamox with the belief that it might mask AMS symptoms and therefore leave a climber more susceptible to dangerous AMS conditions like pulmonary issues or brain swelling. However, this has been found to be false. I can attest that I certainly felt mild altitude sickness on Kilimanjaro while taking Diamox.

It does not prevent AMS from getting worse

This is likely one of the reasons for the ban of Diamox by some guides. They are concerned that climbers consider it a ‘wonder drug’ and will continue to push themselves even when their body cries for help. Whether or not you take Diamox, ALWAYS listen to your body. If it is crying out to you (either through splitting headaches, incredible fatigue, or extreme nausea), listen to it. And tell your guide immediately.

Taking Diamox is not a “pure” way to climb

This is more of personal decision. I consider Diamox a tool; almost like a piece of gear that I choose to use or not. Can you summit Kilimanjaro without wearing gaiters ? Sure. But I choose to wear them because they help prevent an issue: getting rocks and snow in my boots. I think of Diamox in the same way. And, for the record, I rarely take it on my climbs under 12,000 feet (instead opting to spend more time on the mountain to acclimatize). However, I don’t think I’ll ever climb Kilimanjaro without it…the time and money investment is just too high and I want everything in my favor to maximize my chance of summiting.