Hair treatment agents and methods for treating hair using the hair treatment agents are provided. In an embodiment, a hair treatment agent comprises: at least one anionic surfactant from the group of a-olefin sulfonates; at least one anionic surfactant from the group of taurides; at least one amphoteric surfactant; at least one silver salt selected from silver acetate, silver adipate, silver citrate, silver galactarate, silver gluconate, silver lactate, silver malate, silver mandelate, silver salicylate, silver succinate, silver sulfate, and silver tartrate; and at least one organic acid selected from adipic acid, succinic acid, citric acid, acetic acid, galactaric acid, gluconic acid, malic acid, mandelic acid, lactic acid, salicylic acid, sulfuric acid, silver acetate, and tartaric acid, to reduce or prevent washing out of color from dyed hair.