Provocative use testing of methyldibromo glutaronitrile in a cosmetic shampoo

Methyldibromo glutaronitrile (1,2-dibromo-2,4-dicyanobutane, MDGN) is a component of Euxyl K400, a broad-spectrum preservative increasingly used in cosmetics over the last 10 years. Contact allergy to MDGN is not uncommon, with leave-on cosmetics and moistened toilet tissue being the most important sources. Rinse-off products have rarely been reported to elicit allergic reactions in patients sensitized to MDGN and shampoos have only been implicated in hairdressers. To determine whether subjects sensitized to MDGN would react in a provocative use test with a shampoo containing the preservative, we asked 12 pre-sensitized subjects to use a shampoo containing 0.02% MDGN for a period of 9-13 weeks. During this time, none of the subjects showed any skin reactions indicative of contact allergy. The results of this study provide evidence to support that a shampoo product containing 0.02% MDGN may safely be used by most individuals who are presensitized to MDGN.