Benzalkonium Chloride: An Irritant and Sensitizer.

Background: Benzalkonium chloride (BAK) is a known irritant, and potentially cross-reacting quaternary ammonium compounds are commonly used as preservatives in personal care products.

Objective: The aim of the study was to review positive reactions to BAK in 615 patients patch tested for suspected allergic contact dermatitis.

Methods: A retrospective chart review was performed in 615 patients patch tested from June 2015 to October 2016. All patients were tested to a Modified American Contact Dermatitis Society core series of 70 allergens including BAK (0.1% aqueous). Initial readings were performed at 48 hours with final readings performed between 72 and 168 hours. Results were graded as + (weak: papules and erythema), ++ (strong: papules and edema or vesicles), or +++ (extreme: coalescing vesicles, spreading or bullous reactions).

Results: A total of 141 men (23%) and 475 women (77%) were tested (mean age, 49 years). Four hundred thirty-two (70%) were atopic. Of 615 patients, 198 (32%) tested positive to BAK, and 64 (10%) had ++ or +++ reactions at their final reading. On average, BAK-positive patients were using at least 1 product containing BAK or possible cross-reactors.

Conclusions: Widespread exposure to irritants in dermatitis patients can predispose to sensitization. Products containing BAK or potential cross-reactors should be used carefully in patients with compromised skin barriers.