Confront her. Most likely she thinks you guys are close enough to "share". She might not even think she is doing anything wrong. You probably told her once she could borrow them and she doesn't realize that doesn't mean she can keep them in her bathroom! It sounds like miscommunication to me. So talk it out. Otherwise, start hiding your stuff or look for another roommate!

Go talk to her. She's probably just so used to you that she figures it's ok for her to borrow your stuff. She probably doesn't realize you don't like it.

I would talk to her. I had a flat mate who knew NO boundaries once and took from me whatever she needed. I told her how I felt and that she needed to stand on her own 2 feet and not take my stuff. Needless to say she kept taking my stuff and I kicked her to the curb.

I'm living with 5 other girls and my advice to you depends on how you feel about sharing your things and how much you trust this girl.
If she likes so much your products, you can ask her if she wants to have an agreement : you share those products and take turns to buy them (once you, once her). As long as you both pay for your turns, this deal can be a lot of fun.
If you don't mind sharing but what annoys you is that she keeps it in her bathroom/ room/whatever and never ask you if she can just borrow it : talk to her and just tell her that as long as she asks you before-hand and gives it back (clean, especially with clothes) it's okay.
But if you really hate to share those type of things, just tell her with tact to stop (there's no going around that).
I hope your situation will get better :)

I'm living with 5 other girls and my advice to you depends on how you feel about sharing your things and how much you trust this girl.
If she likes so much your products, you can ask her if she wants to have an agreement : you share those products and take turns to buy them (once you, once her). As long as you both pay for your turns, this deal can be a lot of fun.
If you don't mind sharing but what annoys you is that she keeps it in her bathroom/ room/whatever and never ask you if she can just borrow it : talk to her and just tell her that as long as she asks you before-hand and gives it back (clean, especially with clothes) it's okay.
But if you really hate to share those type of things, just tell her with tact to stop (there's no going around that).
I hope your situation will get better :)

Just tell her to please ask you before she uses stuff. Maybe you need to wear certain outfits or need products. Tell her to just shoot you a text or something. And it's not that you don't trust her, but you don't want to be looking for something she took!