The term mental illness is, historically, a medical term implying problems that may require medical treatment. The term mental illness can be used in reference to those psychological problems such as schizophrenia, other psychotic disorders, possibly bipolar disorder, sometimes severe depression, and occasionally severe personality disturbances.

Psychologists tend to not use the term mental illness to describe psychological problems because there is confusion about what the label really means.  Some people have a false impression that psychologists only treat mentally ill individuals, and if you just have a problem with anxiety, an addiction, or “everyday problems” you should see someone else. As a consequence, some people may contact counsellors, with much less training than a licensed psychologist, when they need help to resolve a psychological problem. Rather than being concerned about the label, ask yourself if you have a problem that you are not able to deal with effectively.  A psychologist can help you identify the thoughts, feelings and behaviours that are creating problems in your life and can help you resolve these problems.