Presumed airborne contact allergy to methylisothiazolinone causing acute severe facial dermatitis and respiratory difficulty.

Methylisothiazolinone (MI) is a biocidal preservative (1) that is commonly used in cosmetics, wet-wipes, paint, and household products. MI is used in cosmetics (now supported only for rinse-off products) in combination with methylchloroisothiazolinone (MCI) at a concentration of 3.75 ppm. Since 2005, MI has additionally been permitted as a stand-alone preservative in cosmetic products at up to 100 ppm. There is now an epidemic of contact allergy to MI (2). Recently, several cases of airborne contact dermatitis caused by MI have been published and highlighted (3).