Flexural allergic contact dermatitis to benzalkonium chloride in antiseptic bath oil

Benzalkonium chloride (BAK) is an acknowledged irritant but has also been identified as a cause of allergic contact dermatitis. The antiseptic bath emollient Oilatum Plus (Stiefel, High Wycombe, U.K.) contains a relatively high concentration of 6% BAK. We describe six patients who presented with flexural eczema, particularly involving the anogenital area, who had a history of using Oilatum Plus. Patch testing showed all six to have a type 4 allergy to BAK as well as other allergens. Avoidance of Oilatum Plus led to a resolution of the flexural eczema in each case.