By Michael Vlessides

Calgary, Alberta—Medical professionals might be underestimating the anaphylactic potential of chlorhexidine, one of the most common antimicrobial agents in the OR, according to a recent study in Canada.

Although the study found that the majority of clinicians were aware of chlorhexidine’s allergic potential, the frequency with which the agent causes anaphylaxis was markedly underestimated. The researchers also found that almost one in 10 patients who identified as having a reaction to chlorhexidine were subsequently given the products.

“Chlorhexidine is a ubiquitous antiseptic that is used in the operating room every day,” said Julena Foglia, MD, a resident at the University of British Columbia, in Vancouver. “However, it is also known to commonly cause anaphylaxis.”


Indeed, a recent study (Br J Anaesth 2018;121[1]:159-171) showed that chlorhexidine is one of the top three agents causing perioperative anaphylaxis throughout the United Kingdom. Moreover, one-third of diagnosed patients have had subsequent anaphylactic episodes from repeated exposure to chlorhexidine.


“I started this project because I realized when I started my residency that not many of my colleagues fully appreciated the allergic potential of chlorhexidine, even though it was everywhere in my institution,” Dr. Foglia said.


To help determine the level of awareness at the academic tertiary care center, the researchers distributed a 10-question survey to all relevant perioperative personnel over a 30-day period. Six of the questions collected data, while four distractor questions were included to increase the survey’s validity.

Low Awareness

As Dr. Foglia reported at the 2019 annual meeting of the Canadian Anesthesiologists’ Society (abstract 636763), although 83% of the 98 respondents were aware that chlorhexidine causes perioperative anaphylaxis, only 31% were aware that chlorhexidine is one of its top three causes (P<0.0001).

The researchers also performed subgroup analysis, which revealed that although physicians trended toward more awareness than nonphysicians (87% vs. 74%), these differences were not statistically significant (P=0.129). Nevertheless, only 36% of physicians were aware that chlorhexidine is one of the top three causes of perioperative anaphylaxis.


The survey also found that whereas 53% of physicians encountered patients with skin reactions to chlorhexidine, only 25% referred the patient to an allergist.

“That’s a significant percentage of patients that physicians have come in contact with who are allergic to chlorhexidine but were not sent on for perioperative testing,” Dr. Foglia commented.

Perhaps most alarming was the finding that 8.7% of perioperative staff had exposed a patient to chlorhexidine, even though the patient had identified himself/herself as previously reacting to the antimicrobial agent.

“This figure is quite concerning to us,” Dr. Foglia said. “Yet it correlates very well with published data that show that up to 30% of patients who come to allergists have had multiple exposures to chlorhexidine, which increases morbidity and mortality within the hospital system.”


Given these findings, the researchers stressed the need for widespread education regarding chlorhexidine’s role in perioperative anaphylaxis, an undertaking they hope will reduce reexposures to the agent.

“The second thing I pulled from this is there’s a need for an established allergy clinic where these patients can be seen,” she added. Streamlined patient referrals for allergy testing will help diagnose cases of chlorhexidine anaphylaxis and increase patient safety in the perioperative period.

As Dr. Foglia reported, the results of the survey have opened the doors to her realizing her educational efforts. She has since led two grand rounds on the subject and helped spur the creation of a perioperative anaphylaxis clinic at the institution.

“We need to have safety nets for these patients when they come into the operating room,” she added. “We need bundles and equipment that are chlorhexidine-free that you can grab at 3 o’clock in the morning. And these should be available in all centers, not just the large urban centers.”


“Do you have a sense of people’s awareness of what contains chlorhexidine?” asked session moderator Lucie Filteau, MD, an assistant professor of anesthesiology at the University of Ottawa, in Ontario. “Because people call them alcohol swabs, but when you actually look at the packaging, it’s chlorhexidine,” Dr. Filteau added. “And I’ve noticed that people don’t seem to realize that it’s not alcohol.”

“Unfortunately, I didn’t assess that as part of this study,” Dr. Foglia replied. “However, I’ve worked on another project that showed that most do not know where chlorhexidine is found.”