I have use xxtra clean 4 times before and I passed all the piss tests, however you only need to fill the bottle up once with water and drink that, dont drink alot of water with xxtra clean or you delute and fail or they make you retest, but I would use detoxify again if I started smoking again. oh yeh , dont get that little bottle of it, get the big bottle i dont know how many OZ it is, but this girl I know had a little bottle of it and I though it was funny