Should Diamox Be Continued Throughout the Entire Mountain Trip?
Yes, Diamox (acetazolamide) should be continued throughout your time at high altitude, including both ascent and descent, and should only be discontinued after you have descended and remained at lower altitude for at least 48 hours.
Dosing Duration Based on FDA Label and Guidelines
The FDA-approved dosing for acute mountain sickness specifically states that acetazolamide should be initiated 24-48 hours before ascent and continued for 48 hours while at high altitude, or longer as necessary to control symptoms 1. This is not limited to just the ascent phase.
The cardiovascular guidelines reinforce that patients should continue pre-existing medications at high altitude 2, and this principle extends to acetazolamide when used for altitude prophylaxis.
Why Continue During Descent?
The key physiological issue is that going up and down the mountain means you remain at high altitude even during descent portions of your trip. The risk factors that make acetazolamide effective don't disappear just because you're moving downward temporarily:
- Your body remains exposed to hypobaric hypoxia throughout the trip
- Acetazolamide works by inducing metabolic acidosis that stimulates ventilation and improves oxygenation 1
- Stopping the medication while still at altitude removes this protective effect
- Re-ascent after partial descent (which you describe as "going up and down") puts you at renewed risk for acute mountain sickness
Practical Dosing Algorithm
Standard prophylactic dosing:
- Start 24-48 hours before initial ascent
- Continue 125-250 mg twice daily throughout your time above 2,500-3,000 meters 1, 3, 4
- For rapid ascents or military/emergency scenarios above 3,500m, higher doses (500-750 mg daily) may be warranted 5
- Continue for at least 48 hours after your final descent to lower altitude 1
Common Pitfall to Avoid
Do not stop acetazolamide just because you're descending temporarily during your trip. The medication should be viewed as continuous prophylaxis for the entire high-altitude exposure period, not just the initial ascent. Discontinuing it while you're still spending nights at altitude or making repeated ascents creates gaps in protection.
The mild side effects (paresthesias, polyuria) are self-limiting and do not warrant discontinuation unless severe 6. These effects are far preferable to developing acute mountain sickness during your trip.