Diagnosis is the process of identifying and labeling specific disease conditions. Diagnostic criteria are standardized groups of signs and symptoms used to decide whether an individual has a particular disease or not. If a person has a certain number of symptoms from the list of possible criteria, then the diagnosis can be made. Once a diagnosis is made, the health-care provider and patient can begin to make decisions about appropriate treatment.

Mental health professionals often treat patients who abuse drugs or alcohol. By consulting diagnostic manuals, medical professionals can make accurate diagnoses of substance use disorders, such as abuse or dependence. They can evaluate signs and symptoms (for example, acute intoxication, withdrawal, and delirium, or mental confusion), and laboratory data (such as blood alcohol content or liver function tests) and use these as a...