The invention relates to compositions comprising a combination of (a) at least one organic compound which carries at least one thiol group and at least one optionally derivatized carboxyl group, for example L-cysteine, and (b) at least one organic compound selected from the group which is formed from cyclic, organic carbonates, glycerol and its derivatives and C4-C12 fatty acid dimethylamides. Using these low-odor compositions it is possible to reductively decolor colored keratin-containing fibers, in particular human hair, in a rapid and effective manner.