Monday 7 May 2018

Aromatherapy for nausea? Inhaled isopropyl alcohol vs oral ondansetron for nausea in the ED; an RCT

A patient with nausea presents to your ED...

A busy triage nurse to hands a patient an isopropyl alcohol pad and says, “sniff on this.” 

Nausea magically disappears.

Believe it or not, this is not a new concept. The use of aromatherapy to reduce post-operative nausea & vomiting has been studied for decades. But it has only just just recently popped its head (nose?) into the ED.

This was a very well conducted RCT that enrolled 122 young adults with a chief complaint of nausea & vomiting >3 on a numerical rating scale. They excluded patients who had already got IV cannulation and prior antiemetic therapy.

They were randomised to one of three arms:
  • Inhaled isopropyl alcohol alone (with oral placebo)
  • Ondansetron alone (with inhaled saline placebo)
  • Both inhaled isopropyl alcohol and ondansetron

They were told to sniff on the isopropyl alcohol pad as much as they like and could get a new/fresh one about every 10 minutes.

The primary outcome was reduction in nausea as measured on a visual analog scale (VAS) at 30 minutes.


Both arms using isopropyl alcohol had reductions in nausea by about 30mm. The ondansetron alone arm only had reduction by 9mm. This was statistically significant and the authors made the expected conclusions.

Despite elegant methods, this study did have some important limitations.
  • It is difficult to blind alcohol. (but you can get blind with alcohol… sorry). This could have introduced bias.
  • Persistence and duration of effect is difficult to gage. What about the repeat customer who states, “you’re not going to try to get me to sniff on that alcohol pad again?”
  • These were low risk patients who didn’t need IV’s.
  • Small studies reporting large treatment effect are often disproven

In the discussion, the authors state the mechanism of action remains unclear but could be “related to olfactory distraction.” Perhaps a nausea voodoo dance would have met with the same effect? Who knows…

What should we conclude?

Inhaled isopropyl alcohol might help some low risk patients in the ED with nausea. It is very unlikely to cause harm. But I still like the idea of a voodoo macarena.



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