A hair treatment agent for reducing and/or preventing the bleeding out and/or fading of artificially produced hair colors is provided herein. The hair treatment agent has a pH value in the range of from about 4 to about 5. The hair treatment agent includes, relative to the total amount of the hair treatment agent, from about 0.01 to about 10% by weight of a lanthanum and/or lanthanide salt, at least one anionic surfactant selected from the group of alkyl (ether) sulfates, sulfosuccinates, ether carboxylic acids, N-acylamino acids having 8 to 24 C atoms in the acyl group, (acyl) isethionates having 8 to 24 C atoms in the acyl group, and mixtures of these surfactants, and from about 0.01 to about 10% by weight of an organic acid selected from the group of maleic acid, lactic acid, acetic acid, propanoic acid, amino acids, and mixtures thereof.
