An anecdotal, nonscientific, postscript, on this oft-recurring theme: I am allergic to sulfa-containing antiobotics, and I have no problems with Diamox. However, on my Kili trip, there was a woman who was allergic to sulfa who had some sort of allergic reaction to Diamox and could not take it. (Like the previous poster, I have experimented with dosage, and take far less than the "recommended" dosage.)
So, back to the original topic: go climb Whitney! Have fun! Be safe!
