If your friend or relative is already addicted to drug then he needs to be admitted in drug rehab center because this is the only way that he will be able to try his best to avoid drugs again by the help of other people. There are expert on this not only to remove toxic chemicals from his body but can teach him to have strong faith and learn that life is an important thing from God. Cleaning your body from toxic chemical is not enough because once you go out in the world but you are not loving yourself then you will get back to your old habit which is using drugs.
I have many friends who are drug addicts, some of them recover completely but the others return back to their old habit and became worst that some of them are now crazy and dead. All of us can help avoid this addiction by teaching people not to use or try it. Start campaigning against drugs in your community and tell the young people why drug addiction is bad in our life and society.