Ive cleansed myself with Niacin a few times. 3 pills a day for 3 days and tons of water.
Took a pee test and it came out clean.
My skin was burning and itching though. Funny story... my buddy asked me how to clean out his system too. I took over some of my tamales and some niacin. I guess the chiles in those things made his skin burn more than the norm. Not a good mix
but funny as hell looking back at it.