A preparation for oxidative dyeing and/or lightening keratin fibers, particularly human hair, contains in a cosmetic carrier (a) a first alkyl glucoside having formula (I) in which R1 stands for an unbranched or branched, saturated or unsaturated C20-C28 alkyl group and n stands for a whole number from 1 to 10, (b) a second alkyl glucoside having formula (II) in which R2 stands for an unbranched or branched, saturated or unsaturated C8-C18 alkyl group and m stands for a whole number from 1 to 10, (c) ammonia and (d) an oxidizer.
