A P.S. on dosage for women of slighter frames.
I saw a doctor who specializes in high altitude medicine before I started doing these types of hikes last year. His recommendation for me (female, 135 lbs), was 62.5 mg/twice a day. That is, the "recommended dosage" on the internet does not necessarily take in sex, weight, etc. I had some minor side effects even at that dosage, and based on my specific circumstances, after talking with some folks on this board and doing some more research, I reduced to 62.5mg taken only once a day before sleep. I do not take any diamox prior to the trip -- given my situation, I only take it the night before sleeping at elevation in excess of 10,000 feet, and that is the only dose I will take unless I am sleeping at a higher elevation the next night. I still get minor side effects at this reduced dosage (minor hand tingling the next morning), but nothing that interferes with my enjoyment of the mountain. Cutting the dosage further made sense for me because my issues occur only at night (which, I've read, is the biggest challenge to acclimatization generally); your experience may differ.