We're all told to be whistle blowers in school. It sounds good on paper and to management but is not practical in the real world. She may have coworkers that are close friends that may take a dim view of you ratting her out. Unless you're prepared to make a change in employers, you may want to keep a lid on it. She'll eventually make a mistake or get snared by a randon drug test. I've only been in nursing since January but have seen enough errors to keep me in the manager's office for hours every day. I'm not perfect either and would prefer to continue working with my team, not under their scrutiny.