An agent for temporarily changing the colour of keratin fibres, in particular human hair, include in an aqueous cosmetic carrier (a) at least one aliphatic and/or aromatic alcohol having 2-8 C atoms (b), at least one colour pigment, and (c) at least one zwitterionic polymer, the total weight of the solid matter (d) included in the agent, with respect to the total weight of the agent, being less than 2.5 wt. %.