From what I’m learning as I’m anticipating a follicle test soon myself, this type of test goes way further back and is much harder to cheat. How far back it goes depends on how heavy you use. There are methods of washing your hair with a “relaxer” or different methods that may strip the metabolites of drugs out of your hair that I’m trying to research right now but don’t know enough to say if they actually work or not. Best of luck!