Diamox is a favorite topic here, so I will share what I observed on Orizaba, the 18,000 footer in Mexico. The rest of the story is at this thread
Orizaba thread I went from 200 ft Richmond VA to Toluca hut 12,000 feet same day. The 4 guys from SoCal same thing. Richard P. from Ridgecrest, CA but he is semi-permanently acclimatized because his mind and body are always up at 14,000 weekly.
I started Diamox 125 twice daily that AM. I think Richard and Abraham did, too.
Next day, we drove to 13,500 Toluca trailhead to start hiking. I was huffing and puffing right out of the gate and knew immediately I would be slow. No headache. Richard kindly stayed back with me, We arrived at the far side saddle 15,000 about 5-10 minutes after the other guys. The time difference does not tell the story. To keep up that close, I had my heart rate and respiratory rate feeling more like 20,000 ft. I have had enough experience to know when to quit. I elected to descend by myself ( easy there) rather than go up higher with everyone else on the slick, icy rocks and fog to true summit 15,500. I was impressed at how well the SoCal guys and Richard did. They arrived back 2 hrs after I did , exactly as Richard predicted.
I was not worried, I knew that Diamox is not a miracle drug, I just needed more time .
We slept more nights up high at LaMalinche, but did not attempt the mountain because of rain and gloom in the "dry " season. No one wanted a 14 hr day of mud-slogging. This was fine with me, even though it meant less acclimatization hiking, I knew that sleeping altitude alone is a huge determinant of acclimatization.
We spent a night at Tlachichuca 8,000 ft, before going to the Piedra Grande hut at 14,000 ft on Orizaba. First afternoon there, I felt good on a brief hike to 15,500 or so (Richard a tad higher), and again the next day with the whole group to 15, 500. I might add that this area in 1997 was a small glacier. Now there is none below this "Labyrinth" area.
The difference was remarkable as usual - a little time works wonders. I had stayed on the Diamox (as had at least 2 of the others) but the main benefit was time.
Orizaba summit day started "Up at 12:15am, off at 1:20am." I placed myself second behind Emelio because I feared being the slowest and clumsiest, but later was elsewhere in the line. We pretty much all kept the same speed so my acclimatization problem had been solved. Richard, of course, was more fit and preferred a faster pace , but dutifully stayed in the "sweep" position, trying to stay warm at our slow speed.
That is all I have to say. 18,000 felt easy when acclimatized .I have been on others mountains where over 20,000 felt awful, other times easier. A lot depends on acclimatization, but also weather, workload, etc.
Of course, what we do NOT know, is how I or the others would have done without the Diamox. Our experience was anecdotal, and only with other multiple experiences and/or official medical studies has the answer been said that it does help speed up acclimatization (sometimes, and for some people, but no guarantees)
Coming down for me was an altogether different problem with weak quads, not an acclimatization issue. Harvey
