Vitamins and Supplements How long until niacin cleans your system Posted on February 16, 2019February 20, 2018 by admin Niacin does not clean drugs — any drug — out of your system. Related posts: Is inositol hexanicotinate effective in lowering cholesterol Why are some b vitamin numbers skipped What are all the vitamins You smoked a blunt 16 days ago you took an entire bottle of flush free niacin for a week you worked out occasionally and drank a good amount of water up until your UA Will your results come back to yo