Brightening and/or colouring agent with reduced potential for irritation

Valine is used in compositions for dyeing or lightening keratinic fibers. Independent claims are also included for: (1) composition for dyeing or lightening keratinic fibers, comprising 0.05-10 wt.% valine and 0.01-10 wt.% of a cationic or amphoteric polymer; (2) dyeing or lightening keratinic fibers by optionally applying a pretreatment composition (C1), applying a tinting or dyeing composition (C2), optionally after adding another composition (C3) to C2, rinsing off C2 after 5-45 minutes, and optionally applying an aftertreatment composition (C4) and rinsing off C4 after a few minutes, where at least one of C1-C3 is a composition as above. Mittel zum Färben und/oder Aufhellen keratinischer Fasern, insbesondere menschlicher Haare, die, bezogen auf ihr Gewicht 0,05 bis 10 Gew.-% Valin sowie 0,05 bis 10 Gew.-% kationische(s) und/oder amphotere(s) Polymer(e) enthalten, lassen sich mit besonderem Vorteil in Haarfärbe- und -aufhellungsmittel einarbeiten und führen zu einer Verringerung des Irritationspotentials dieser Mittel.