The hazards of moist toilet paper: allergy to the preservative methylchloroisothiazolinone/methylisothiazolinone.

Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), a common preservative in some brands of moist toilet paper (baby wipes and moist towelettes), has been reported to be a cause of allergic contact dermatitis. However, few cases have been reported in the United States. We report the cases of 4 adult patients with severe perianal and perineal allergic contact dermatitis seen at our institution during a 6-month period. With patch testing, we identified allergy to MCI/MI, and we determined that all 4 patients were using moist toilet paper. The dermatitis resolved after use of the moist toilet paper was discontinued. This study highlights that the MCI/MI in moist toilet paper can be a cause of perianal and perineal allergic contact dermatitis.