When an individual is diagnosed with a substance use disorder and a co-existing mental health disorder, the paired disorders are referred to as co-occurring disorders, also known as dual disorders. 

Common comorbid mental health disorders include depression, anxiety, manic depression (bipolar disorder), panic disorder and Attention-Deficit/Hyperactivity Disorder (ADHD). Although the association is usually linked with a mental health disorder, the comorbidity may also include a physical health disorder (e.g., heart disease, HIV infection, or Hepatitis C) or other disorders.