You most likely CAN'T. Alcoholics and drug addicts live in a state called denial. Any and all prompts to tell them they have a 'problem' will result in that denial rearing its ugly head. In the case of his being an offensive person, he most likely will take great offense as being told he has a problem. You will tell him, and tell him again, and again, and again, and each time he will meet it with anger, denial, resentment whatever. Eventually he will understand that you were right - if he is an alcoholic. However that will take him reaching his 'bottom'. A bottom is an event or a series of events that underlines that alcohol/drugs are a problem in a persons life - then and only then do they do the first step: 1. We admitted we were powerless over alcohol (Drugs, anything that is our addiction)—that our lives had become unmanageable. This does not mean that we learn from what somebody tells us, or learn because somebody wishes we understood we had a problem, it means we have to go through that one (or several) event(s) that underlines that we are powerless over our drug of choice and that our life is not manageable. Unfortunately the 'bottom' leaves us with wreckage: The wreckage in a recovering person's life tells you lots about their bottom. usually that wreckage is a divorce, a bad credit history, debt up to our eyeballs, broken family relationships - all of these things take place because our addiction leads us down the road of problems. Interventions do not work either. more often than not they just drive the problem into secrecy and the addict/alcoholic will play the game (so to speak) and pretend to be clean/sober, in reality they are doing their drug of choice in secret, hiding it which can be far more dangerous than being out and open about it since no nobody knows what they are dealing with - the person or the drug/drink. I would suggest Alanon for you and other loved ones. Alanon is for loved ones of alcoholic addicts, they help YOU to deal with the problem in a way that protects you and they can give pointers on how to better present your case in a way that does not lead you into being as offensive. they most likely will tell you about not enabling and staying away when he is drinking, or telling you to tell him he is not welcomed when drinking. The alanon website is found here: http://www.al-anon.org/