ABSTRACT
INTRODUCTION Alcohol, illegal drugs and prescribed drugs used in excess or in risky circumstances can be considered a substance use problem. Why one person becomes dependent and another does not is a fascinating and complex issue but beyond the scope of this chapter. Here we are concerned with the individual whose substance use has impacted on their health in the long term. Individuals with this problem may have periods of remission but may also relapse at times and require further intensive interventions.
