Contact allergy and allergic contact dermatitis from benzalkonium chloride in a tertiary dermatology center in Melbourne, Australia.

BACKGROUND

Benzalkonium chloride (BAK) is a quaternary ammonium compound that is used widely as an antiseptic and preservative. It is a strong irritant and considered a weak sensitizer.

OBJECTIVE

To analyze the temporal trend of BAK sensitization and the demographics of sensitized patients.

METHODS

We conducted a single-center retrospective study of 7390 patients who were patch tested with BAK between January 1, 2003 and December 31, 2019.

RESULTS

Of the 7390 patients who were patch tested to BAK, 108 (1.5%) had a positive reaction, with 21 reactions deemed clinically relevant (0.3% of total patch tested) and a further 5 doubtful reactions deemed clinically relevant, resulting in a total of 26 relevant reactions (0.4% of total patch tested). Common sources of exposure were ophthalmic drops (30.8%), topical antiseptic preparations (26.9%), cosmetics (15.4%), disinfectant solutions (11.5%), hand sanitizers (11.5%), and hand washes (7.7%). One fifth of patients with relevant reactions were health care workers. There has been a dramatic increase in the number of positive reactions since 2017, for reasons not totally clear.

CONCLUSION

Contact allergy (CA) and allergic contact dermatitis (ACD) in response to BAK are now increasing at our center. Awareness of this trend is important, given that the coronavirus disease 2019 (COVID-19) pandemic is likely to further expose people to BAK.