Coloring agents for keratin fibers, in particular for human hair, include—based on their weight—at least one compound selected from the group of oxidation dye precursors, substantive dyes and mixtures thereof, 0.1 to 5% by weight dicarboxylic acid(s) having 2 to 10 carbon atoms and/or salt(s) of said acid(s), 20 to 95% by weight water and less than 0.1% by weight peroxide compound(s), result in oxidative coloring agents with improved fiber protection.
