Acetazolamide is not licensed for the prevention of altitude sickness although it can be helpful.
The usual dose recommended by the travel doctor is 1 x 250mg tablet taken twice per day.
It’s generally a good idea to try it out for a couple of days before you leave to check for side effects such as tingling or numbness.
You may be advised to start 2 days before before ascent, continuing for 1- 2 days after you’ve reached your highest altitude.
Altitude sickness may be fatal. You will need to descend immediately if you are experiencing significant symptoms.