tablet diamox is acetazolamide: a diuretic (makes more urine) basically used for a lot of problems in which u need to reduce the fluid in body e.g. glaucoma in which the pressure of eyeball increases or in epilepsy where u need to reduce pressure inside the head. its use in altitude sickness AMS is based on the fact that it accelerates acclimatization basically does what the body wud have done anyways but faster. I dont want to go into its details but basically what it does is acidifies blood stimulating hyperventilation i.e. more breathing. The body wud normally do this too and lead to hyperventilation induced CO2 washout and alkalizing the blood. By throwing out bicarb in urine diamox takes care of this alkaline blood n maintains it acidic so as to maintain hyperventilation n good Oxygen carriage. it takes two days to work so its not a fast food therapy for AMS in fact its a poor treatment of AMS but a good prophylaxis or protection against AMS. which means it works best if taken before u get AMS. If u plan to climb from sea level to 10000 feet in one day or more than 2000 feet per day once above 8000 feet u should start taking diamox 400 mg twice or thrice a day depending on body weight three days before u do the ascent. a lot of books and websites will give different dosage and schedules. The above is what i give my patients and tourists who bother to ask us here at Sikkim before goin onward to gurudongmar and it works. trouble is a general fit person has practically little chances of AMS till 12000 feet in my experience so i wonder if diamox is really useful on a routine. obviuosly it will make u take loo breaks more often n therefore lose water so u need a lot of water while taking this medicine. hope this helps.