Under certain circumstances, prophylaxis with medication may be advisable
We do not recommend acetazolamide as a prophylactic medication, except under the specific limited conditions outlined above. Most people who have a reasonable ascent schedule will not need it, and in addition to some common minor but unpleasant side effects it carries the risk of any of the severe side effects that may occur with sulfonamides.
The dose of acetazolamide for prophylaxis is 125-250 mg twice a day starting 24 hours before ascent, and discontinuing after the second or third night at the maximum altitude (or with descent if that occurs earlier). Sustained release acetazolamide, 500 mg, is also available and may be taken once per day instead of the shorter acting form, though side effects will be more prominent with this dose.
Recently some exciting work has been done studying the use of Ginkgo biloba extract to prevent AMS. Much more work remains to be done, but in three studies Ginkgo has been shown to be very effective in preventing or lessening the symptoms of AMS. It has yet to be determined exactly how Ginkgo works at altitude, but it may act as an antioxidant, reducing stress on tissues that have been injured by low oxygen levels.
These studies used a standardized Ginkgo biloba extract (24% flavonoid glycosides, 6% terpenoids). The dose used was 80 - 120 mg twice a day, starting 5 days before a rapid ascent or at the beginning of a gradual ascent. ConsumerLab.com is an independent lab that tests herbal products to ensure that they contain what the label promises; they have a page evaluating Ginkgo products available in the USA.
125-250 mg (depending on body weight; persons over 100 kg (220 lbs) should take the higher dose) twice a day starting 24 hours before ascent, and discontinuing after the second or third night at the maximum altitude (or with descent if that occurs earlier). Children may take 2.5 mg/kg of body weight twice a day.
80 - 120 mg twice a day, starting 5 days before a rapid ascent or at the beginning of a gradual ascent. tory depression (the slowing down of breathing) can be caused by various medications, and may be a problem at altitude. The following medications can do this, and should never be used by someone who has symptoms of altitude illness (these may be safe in persons who are not ill, although this remains controversial)