Written by: Kruti Patel
First it is important to understand what is happening to your body when you climb to higher elevations and then you can understand how the drug, Acetazolamide, sold under the trade name, Diamox, attempts to help your body on Kilimanjaro.
Often times you’ll hear people say that as you climb there is less oxygen and therefore you are unable to breath. This is not true. The percentage of oxygen in the air at sea level (around 21%) is actually the same amount at high altitude. However, air is compressible, and so when you are standing at sea level, the weight of all the air above us (also known as the atmosphere) is compressing the air around us. As you go to higher elevations, the air becomes less compressed and therefore the air molecules are more dispersed. Since the air molecules are more dispersed, each breath you take in delivers less oxygen to your body.
So how does your body react to this decrease in pressure? Well, from what I’ve read, a lot of “stuff” happens, however since this post is focused on how Diamox in particular can help at high altitude, I’m going to focus in on what particularly is happening to the pH level of your blood and then it’ll become more clear what Diamox’s role is in helping with altitude sickness.
About 90% of carbon dioxide in your blood is in the form of bicarbonate (HCO3); the rest of the carbon dioxide is either dissolved carbon dioxide gas (CO2) or carbonic acid (H2CO3). Your kidneys and lungs balance the levels of carbon dioxide, bicarbonate and carbonic acid in the blood. CO2 is a gaseous waste product from metabolism, and the blood carries CO2 to your lungs, where it is exhaled.
From my explanation above, since there is a decrease in air pressure as you climb, you naturally start breathing harder or what is often referred to as hyperventilation, because you are trying to get more oxygen into your body. However breathing excessively also means you are start-exhaling CO2 at a higher rate. The corresponding levels of bicarbonate in your body stay constant. As a result your blood becomes alkalinic (increased pH). This then causes the onset of altitude sickness symptoms.
So how does Diamox help in this particular situation? It helps your body get rid of the bicarbonate. To be more specific, it works in the kidneys, where it increases the amount of bicarbonate that passes into the urine. By instructing the kidneys to more rapidly excrete the HCO3, you blood can become more acidic and compensate for the low levels of CO2 caused by excessive breathing (respiratory alkalosis).
Everybody’s body is different and everyone’s reaction to higher elevations differs. I personally took Diamox on my climb and followed my Doctor’s recommendation to start taking it about 24-48 hours before getting into higher altitudes and then continued taking it for 48 hours after having reached the summit. I wanted to write this post to explain that it does help counter the imbalance between CO2 and HCO3, but it is not a miracle drug that will keep you from getting altitude sickness. I think the best way to avoid altitude sickness is by making sure you do proper training, climbing slow, exaggerate your breathing throughout the climb and proper acclimatization (which I’ll write about in another post!).
The two most common side effects listed for Diamox are more frequent urination (which makes sense given some of the explanation above) and a tingling sensation in your fingertips and toes (I was unable to figure out why this happens, but I definitely experienced it when I took it). As with any drug, be sure to speak with your doctor first about your specific situation before taking Diamox.