Really depends on how far you want to push it. My daughter was obviously on drugs/cutting a few years ago(she's 22 now) and I had her either take a drug test or find somewhere else to stay. It's impossible to know what they/you are dealing with, without knowing the cause. I'm lucky to say that I was able to get her the help needed and she's now a successful young lady with a promising career. I used to worry and drink about her and her future... now I'm the one climbing out of my own hole. Boundaries and stick to them, is all I can say. Also..don't let him pull the: "but you do/did's,ect.." Let him know it's your home and it's tough on the 'streets'. Best wishes.