In combination with methylisothiazolinone, it goes by the trade name Kathon CG (among others). Introduced into cosmetics in the mid-1970s, it elicited a great number of sensitizations in consumers. This led to it not being included in cosmetics other than rinse-off products (Sources: Contact Dermatitis, November 2001, pages 257–264; and European Journal of Dermatology, March 1999, pages 144–160).
Methylchloroisothiazolinone, when combined with methylisothiazolinone, offers broad-spectrum activity against microorganisms. This blend is being used in many products instead of parabens, despite the fact that parabens have a better safety track record and lower incidence of causing a sensitized reaction. Along with methylisothiazolinone, this preservative has maintained its reputation as a frequent allergen in leave-on products, particularly hair care and feminine hygiene (Source: Contact Dermatitis, November 2011, pages 276-285).