It works for about half the people that try it from what I have read. I got lucky. I never had luck with anything else. Mine likely stems from mild hereditary ocd FWIW. It's one of those problems I never thought a pill would fix, let alone a supplement lol.
https://www.bfrb.org/post/n-acetylcysteine-for-hair-pulling-skin-picking-and-nail-biting
You'll want to look at the studies for dosages.
True, I've talked to a professional. :) I'd recommend the same. The liquid wasn't working for me nor were acrylics.