Side-effect of acetazolamide in prevention of acute mountain sickness

Abstract

The scientific letter by Firth et al. (S Afr Med J 2011;101:462) about the side-effect of acetazolamide on a hiker on Mt Kilimanjaro makes a rather hasty conclusion about the recommendation of acetazolamide to prevent acute mountain sickness (AMS), especially in a rapid ascent climb such as Kilimanjaro. It is difficult to disagree about the pathophysiology of acetazolamide causing corneal oedema, but we must note that it is a drug used for glaucoma treatment, and the dosage regimen is usually higher than that prescribed for the prevention of AMS. Interestingly, the authors did not mention the dose and duration of acetazolamide in the article. The cause-effect relationship is difficult to establish from this case report without knowing the dosage regimen and control. Based on the rare side-effect (if indeed it is) in this report, it would not be justifiable to advise against using acetazolamide as a prophylactic of AMS; this could rather invite other serious acute altitude illnesses that would be far more probable were it not used. Major trials with large numbers of participants have reported a fairly safe outcome of acetazolamide. Hence, we should continue using acetazolamide with caution for preventing AMS where there is rapid ascent profile.
Reply by P G Firth, C Gray and C Novis.