Acetazolamide for preventing high altitude illness

Evidence Summaries

Level of Evidence = B
Acetazolamide appears to reduce the incidence of acute altitude sickness compared with placebo.

The quality of evidence is downgraded by study limitations (unclear allocation concealment and detection bias).

A Cochrane review 1 included 64 studies with a total of 4547 subjects. The risk of acute mountain sickness (AMS) was reduced with acetazolamide (table T1). Few studies reported side effects for this comparison, and they showed an increase in the risk of paraesthesia with the intake of acetazolamide. For dexamethasone, there was a trend towards reduced acute mountain sickness, but it was insignificant.

Table 1. Acetazolamide/dexamethasone compared with placebo for preventing high altitude illness
Outcome Relative effect (95% CI) Assumed risk - Placebo Risk with intervention - Acetazolamide No of Participants (studies)
Incidence of acute mountain sickness RR 0.47 (0.39 to 0.56) 241 per 1000 113 per 1000 (94 to 135) 2301 (16)
Incidence of high altitude pulmonary oedema (HAPE) Not estimable No events 1138 (7)
Incidence of high altitude cerebral oedema (HACE) RR 0.32 (0.01 to 7.48) 2 per 1000 1 per 1000 (0 to 14) 1126 (6)
Outcome Relative effect (95% CI) Assumed risk - Placebo Risk with intervention - Dexamethasone No of Participants (studies)
Incidence of acute mountain sickness RR 0.6 (0.36 to 1) 449 per 1000 270 per 1000 (162 to 449) 176 (4)

References

1. Nieto Estrada VH, Molano Franco D, Medina RD et al. Interventions for preventing high altitude illness: Part 1. Commonly-used classes of drugs. Cochrane Database Syst Rev 2017;(6):CD009761.  [PMID:28653390]
Copyright © 2023 Duodecim Medical Publications Limited.