Lots of places drug test on interview, but won't drug test again during employment unless there's an accident or something to give them cause to do so.
I took this stuff call golden seel root about two weeks before getting urine drug test. UA came back clean. It's an herb or whatever that you can get at Wal-mart in the herbal supplement aisle.
The only thing is that the fingers on my right hand started turning yellow. The herb acts as a detoxifier. And I was smoking at the time. And because the herb was in my system, it wouldn't allow the nicotine to be absorbed through my skin. I think I took the stuff for a week, drinking lots of water. And then quit it for a week before the drug test and it was clean.
I know that some UA tests actually test now for detoxifiers, but that's usually only with jobs that have you handling massive amounts of money or have you driving kids in a schoolbus or where you have a lot of high end responsibility.