It is best to do your homework before you confront your loved one.
Despite what some reality shows may air on television, confronting a drug addict should be done in a gentle manner and not one which will make the addict feel overly defensive.
Find out if insurance covers addiction recovery and find out some information about local (and some not so local) drug treatment centers. You will want to be well armed even though you must try to remain calm and supportive when you confront your loved one. While you are checking out rehab programs, you may want to request information on intervention programs just in case the confrontation does not work.
As much as you love them, you cannot allow their addiction.
Only confront the addict when they are sober. Remember that even though they are sober and you are being gentle, they are still going to resist. When you confront them, start out with the fact that you are worried about them. Try to remain positive in tone and in thought. Eventually, in the conversation, you are going to have to let them know that you will no longer enable them. For instance, you will not call in sick for them anymore. Let them know you are doing this for their sake, even though they are going to argue with you. Let them know you will no longer pay their bills if you have been doing so. If the confrontation becomes violent, call the police. They are responsible for their own behavior. You did not cause the addiction and you cannot make it go away. The addict has to make decisions for themselves.
As tough as it may seem, always try to remain positive. As much as you love them, you cannot allow their addiction to send you into a lifelong depression.
They need to get help.
You are merely offering suggestions. If they continually refuse confrontation, find out about intervention. Intervention is a step beyond confrontation and is usually done with the help of a trained professional. In the meantime, do not allow yourself to be an enabler. Let the addict suffer the consequences of their actions. It may seem harsh, but it is not. They must see for themselves what their addiction is doing to them. Unfortunately, it is true that some must hit rock-bottom before they start their climb back up.