Zwitterionic azo dyes for dyeing keratin fibers

The invention relates to compositions for dyeing keratinous fibers, in particular human hair, containing at least one compound of formula (I) in a cosmetic carrier. The structures of the general formula (I) having a heterocycle A, which is a quaternary nitrogen atom and therefore carrying a positive charge. Furthermore, the invention relates to the use of these novel azo dyes in compositions for dyeing hair as well as the dyes themselves.