The subject matter of the present disclosure is an agent for the reductive decolorization of dyed keratinous fibers, more particularly human hair, containing, in a cosmetic carrier:(a) Formamidine sulfinic acid and/or salts thereof and(a) At least one compound of formula (I)Additional subjects of the present disclosure are corresponding multi-component package units and methods for reductive decolorizing of dyed keratinous fibers.
