The present disclosure relates to compositions comprising at least one soluble fluorescent dye and at least one compound comprising an acid functional group, and to processes using this composition.It likewise relates to a method of using compositions comprising, in a cosmetically acceptable medium, at least one soluble fluorescent dye and at least one compound comprising an acid functional group for dyeing human keratin materials, such as artificially dyed and/or pigmented hair and dark skin, with a lightening effect.