Addiction is a complex disease influenced by biological, psychological, and social factors. Treatment works and is cost-effective in the long run. There are three components to addiction: loss of control over substance use, compulsion to seek and take the substance, and chronic relapsing nature. Addiction is a brain disease that changes the brain in fundamental and lasting ways. Most people with addiction also have co-occurring mental health disorders, and outcomes are generally worse for those with co-occurring disorders compared to those with only substance abuse or a mental illness. Recovery is a process that involves abstinence, developing a sense of responsibility, managing a range of emotions, and developing intimacy.