Yes, you can take it 24-48 hr before a rapid ascent. It should be continued 48 hrs after descent. Polak has great point about going slow anyway to avoid the necessity of acetazolamide. You can take it up to 250mg four times daily, but twice daily dosing is fine. *NO loading dose is necessary*

Side effects listed in the literature are many, but most common is peeing tons (duh!) I haven't had too many complaints from patients when they come back, but we don't do alot of this medication.