Does hair bleach damage hair?

Hair bleach is damaging to the hair and should only be applied by a professional. Bleaching hair can permanently raise the hair cuticle, which may contribute to a rapid loss of moisture.

Damaging side effects from hair bleach include brittle, dry hair; loss of elasticity; and split ends and breakage. Since bleached hair is more porous than unbleached hair, it is more vulnerable to the damages of other non-chemical and chemical processes such as permanents, blow drying and straightening. The amount of hair damage related to bleaching depends on the degree of color change. When coloring the hair from a dark shade to a light shade, damage may be more extensive because the bleach is left on longer.