Yes, rehab (or substance abuse treatment) does really work and can be very helpful for those who struggle with addiction. Effective treatment will help a person work through their physical withdrawal from the drug, develop effective coping skills, and in some situations, provide a safe opportunity to practice those coping skills.
Treatment comes in many forms and the length of stay should be individually tailored to the needs of the person being treated. For those with less severe symptoms, individual counseling a few times a week may be beneficial. People with moderate symptoms may benefit from a program of several hours duration several times each week. Individuals who struggle with substance dependence, or addiction, benefit most from a safe environment, free of substances, where they can begin the recovery process.
Current research indicates that for those who struggle with addiction, treatment should last at least one year. That is not to say that they should be in a rehab facility for that length of time, but that they should maintain a connection to treatment for at least one year for the best results. However, recovery is a life-long process and regular participation in recovery meetings or support groups after treatment has also proven to be very successful in remaining drug-free.
Visit this Resources page for a number of confidential counselors you can talk to to get more information.