Is my friend in any real danger?

My best friend recently told me that she cuts. She uses a scissors on her wrist but swore to me that she only cuts deep enough to break the skin. I've seen her "marks" and they usually seem to disappear after a few days. Is this really endangering her life? I know you have veins and arteries and stuff in your wrist so should I be concerned if she is only cutting to the point where it just starts bleeding a little? Is that really deep enough to cause prermanent damage?