As long as she isnt becoming an addict who then starts stealing to buy more drugs and cant be bothered to get motivated or get a job then all is fine. all things are okay in moderation... Although I haven't really done much in terms of drugs myself (I tried it and didnt like it lol) I had all my house m8s and university do tonnes or stuff and it didnt bother me what so ever. .
My advice is be there for her, but dont smother her, let her do her thing, if things get too serious then step in and do something otherwise just be passive about it. Most kids around that age experiment and its okay for them to do so as long as they take the proper precautions and do minimally. She'll probably grow out of it sooner or later, alot of people I know that settle down drop the whole thing