Disclosed is a method for inhibiting colour / color fading in colour-treated / color-treated hair and enhancing the intensity of colour achieved by colour-treating hair, the method comprising contacting the hair with a composition comprising a carrier and a color fading inhibiting-effective amount of from about 0.1 weight per cent to about 15 weight per cent of a monoalkyl quaternary ammonium salt, which is lauryltrimonium chloride, cocotrimonium chloride, or a combination thereof, wherein the monoalkyl quaternary ammonium salt in the composition exclusively inhibits fading of color in color-treated hair.
