Alcoholic versus aqueous chlorhexidine for skin antisepsis – the AVALANCHE trial.

Talk Code: 
Tom Brett
Clare Heal
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Antiseptic solutions are routinely applied to clean the skin prior to surgery. One of the most common antiseptic solutions is chlorhexidine, which can be dissolved in water or alcohol before being applied to the skin.

Alcohol-based solutions are more likely to irritate the skin and eyes, and remove markings drawn on the skin to guide the surgeon.

Despite this, we hypothesised alcoholic chlorhexidine might be a better antiseptic than a water-based solution, as alcohol is an antiseptic in its own right. We could find no current consensus in the medical literature




Our objective was to compare skin antisepsis with alcoholic chlorhexidine (CH) against aqueous CH for prevention of surgical site infection (SSI) after ‘minor skin excisions’ in general practice.

This prospective, multicentre, randomised controlled trial was conducted in four private general practices in North Queensland from October 2015 to August 2016.Consecutive adult patients presenting for minor skin excisions were randomly assigned to the intervention of preoperative skin antisepsis with 0.5% CH in 70% ethanol, or the control of 0.5% CH aqueous solution.Our primary outcome was SSI within 30 days of excision.We also measured incidence of adverse reactions.


A total of 916 patients were randomised: 454 to alcoholic CH and 462 to aqueous CH: 909 completed follow up. There was no significant difference in the incidence of SSI in the alcoholic CH arm (5.8%, 95% CI 3.6-7.9%) compared to the aqueous CH arm (6.8%, 95%CI 4.5-9.1%) in the intention to treat analysis of available cases at follow-up (p=0.5852). The attributable risk reduction was 0.010 (95%CI -0.021, + 0.042), the relative risk was 0.85 (95% CI 0.51–1.41) and the Number Needed to Treat to benefit was 100. Per protocol and sensitivity analyses produced similar results. The incidence of adverse reactions was low with no difference between groups. (p=0.6242).


There was no significant difference in efficacy between alcoholic and aqueous chlorhexidine for the prevention of SSI after minor skin excisions in general practice and we recommend that non-alcoholic antiseptics can be used safely and effectively for minor surgical procedures.

Submitted by: 
Clare Heal
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