Addiction is a chronic, relapsing disorder characterized by compulsive drug seeking, continued use despite harmful consequences, and long-lasting changes in the brain. It is considered both a complex brain disorder and a mental illness. People with addiction (severe substance use disorder) have an intense focus on using a certain substance(s), such as alcohol or drugs, to the point that it takes over their life.

Addiction can begin with the voluntary act of taking drugs or drinking, but over time a person’s ability to choose not to do so becomes compromised. This impairment in self-control is the hallmark of addiction, with genetic, environmental, and psychological factors all contributing to the development of the disorder.