Addicted to painkillers

I have a relative that I believe is addicted to painkillers. Of course if you talked to him about it he would probably not agree. But, he doesn't seem to be able to function without them. The problem is he does have pain that does need to be treated. His physician is one of those doctor that gives pain medicine and antibiotics for everything. And my relative keeps going back to he because he gives him what he wants.
I honestly think he could benefit from a drug detox program. I am not sure I can convince him that he needs a detox though. Though I have never been addicted to anything I do know how it can affect your life. My childhood story is evidence of that. I think what my relative needs is a complete detox. Not only because he over uses painkillers but also because of alcohol use and bad diet. Not a pretty picture.