Sudden rise in allergic contact dermatitis to benzalkonium chloride


By Michael Woodhead

10 Mar 2021

There has been a dramatic increase in allergic contact dermatitis with benzalkonium chloride (BAC)-containing products such as antiseptic handwashes – and the problem is likely to worsen because of the COVID-19 pandemic, dermatologists have warned.

While previously thought to be a rare cause of contact allergy, rates have increased 10-fold in recent years, possibly due to a switch to using BAC in personal care products in place of other preservatives,  such as methylisothiazolinone, according to Dr Kate Dear of the Occupational Dermatology Research and Education Centre, Skin Health Institute, Melbourne.

In a new report in Contact Dermatitis, Dr Dear and colleagues describe how the positivity rates of contact dermatitis to BAC seen at their clinic had increased from less than 1% a year to 7-10% since 2017.

Previously the rates had been low with a mean of 1.6 positive reactions of unknown relevance annually and 0.6 relevant reactions annually until 2016.

From 2017 onwards, however, rates of allergic contact dermatitis increased ten-fold to a mean of 21 positive reactions of unknown relevance annually, and 6 relevant reactions annually.

Their review, based on results from 7390 patients patch tested for BAC, found that the most common locations of allergic contact dermatitis were the face (42%) and hands (39%).

In addition to contact allergy there was also a major increase in rates of irritation, with numbers increasing from an average of one per year to 14 in 2019.

The most common sources of exposure to BAC were eye drops (31%), topical antiseptic preparations (27%), cosmetics (15%), disinfectant solutions (12%), hand sanitisers (12%), and hand washes (8%).

And notable, one fifth of patients with relevant reactions were healthcare workers including surgeons and nurses who were using hand sanitiser products. Including disinfectant wipes and sprays containing BAC.

Dr Dear and colleagues said it was not clear exactly whey there had been a recent increase in BAC-related contact dermatitis, but the problem was likely to get widen beyond healthcare workers to the general public with the widespread use of hand sanitiser antiseptic products during the COVID-19 pandemic.

“Increased exposure to BAC through disinfectant solutions and cleaning wipes is likely to occur with the increased need for cleaning and hygiene practices within healthcare settings and businesses in the wake of this unprecedented pandemic,” they wrote.

“While there may be some scepticism regarding the number of positive reactions to BAC¬†because of the irritant nature of the allergen, there should be an increasing awareness of the
allergenicity of BAK, and further studies regarding the trends in rates of contact allergy and allergic contact dermatitis. This is particularly important given the increasing its use in disinfectants, wipes and sanitisers related to hygiene practices in the prevention of COVID-19.”

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