The first step is usually the most difficult one. This is also true for overcoming drug addition. The first step is to help the drug addict realize that he or she needs to seek help regarding his addiction. Once this step is overcome, it becomes easier to help the person get into a treatment program at a rehab center.
Talk to the person
If you want to encourage a drug addict to seek help, the first step is to try a non-confrontational approach with the person. In a conversation, try to mention the problem to the person without trying to blame him or her. Explain how the problem has been affecting him or her. Tell the person how his or her addiction has been affecting you and your relationship with him or her. You may also try to appeal to the emotions of the drug dependent.
Encourage the person's family and friends to speak with the person
If your talk with the drug addict has not been production, it might beneficial to enlist the help of the people who are closest to the person. Try to ask the help of other family members and friends in speaking with the person regarding the problem.
Talk about the person's life goals
In appealing to the person's logic and emotion, you can mention about the person's goals and how these are compromised by his or her addiction. By making the person realize that his or her addiction is getting his or her far from personal goals, it might help him or her recognize the severity of the problem.
Show that you are there for the person
One of the reasons that a person gets into drugs is when he or she feels lonely or left out. Make the person feel that you are concerned about his or her well-being.
Once you feel that the person is already convinced that there is a problem, take the next step immediately. Refer the person to a drug counselor or a rehab center to start with the treatment.

A counsellor who specializes in Addictions can help you better understand your problem, and how to work through it.