If you suspect a teenager is abusing drugs or alcohol, do not panic and do not immediately speak to the teenager about the situation. Speaking to the teenager before you have a plan usually backfires because the conversation quickly disintegrates into a confrontation, which accomplishes nothing. 

The first thing you need to do is think of people in your life who can be helpful and think of professionals to contact. Determine if there is another adult—an uncle, older brother, or favorite cousin—with whom the child has a good relationship and may have some positive influence. Is there a member of the clergy that can be helpful? Does the child have a pediatrician who has been a regular part of his or her care? Think of people in your life who can connect with the child you are concerned about. Enlist one or more of these people to spend time with the child, since he or she might open up to this person when not being open to a parent.