Substance use disorder (SUD) is the persistent use of drugs (including alcohol) despite substantial harm and adverse consequences. Substance use disorders are characterized by an array of mental/emotional, physical, and behavioral problems such as chronic guilt; an inability to reduce or stop consuming the substance(s) despite repeated attempts; driving while intoxicated; and physiological withdrawal symptoms. Drug classes that are involved in SUD include: alcohol; cannabis; phencyclidine and other hallucinogens, such as arylcyclohexylamines; inhalants; opioids; sedatives, hypnotics, or anxiolytics; stimulants; tobacco; and other or unknown substances.In the Diagnostic and Statistical Manual of Mental Disorders 5th edition (2013), also known as DSM-5, the DSM-IV diagnoses of substance abuse and substance dependence were merged into the category of substance use disorders. The severity of substance use disorders can vary widely; in the DSM-5 diagnosis of a SUD, the severity of an individual's SUD is qualified as mild, moderate, or severe on the basis of how many of the 11 diagnostic criteria are met. The International Classification of Diseases 11th revision (ICD-11) divides substance use disorders into two categories: (1) harmful pattern of substance use; and (2) substance dependence.In 2017, globally 271 million people (5.5% of adults) were estimated to have used one or more illicit drugs. Of these, 35 million had a substance use disorder. An additional 237 million men and 46 million women have alcohol use disorder as of 2016. In 2017, substance use disorders from illicit substances directly resulted in 585,000 deaths. Direct deaths from drug use, other than alcohol, have increased over 60 percent from 2000 to 2015. Alcohol use resulted in an additional 3 million deaths in 2016.

The surgeon general of the United States is the operational head of the U.S. Public Health Service Commissioned Corps (PHSCC) and thus the leading spokesperson on matters of public health in the federal government of the United States. The Surgeon General's office and staff are known as the Office of the Surgeon General (OSG) which is housed within the Office of the Assistant Secretary for Health.The U.S. surgeon general is nominated by the president of the United States and confirmed by the Senate. The surgeon general must be appointed from individuals who are members of the regular corps of the U.S. Public Health Service, and have specialized training or significant experience in public health programs. However, there is no time requirement for membership in the Public Health Service before holding the office of Surgeon General, and nominees traditionally were appointed as members of the Public Health Service and as Surgeon General at the same time. The surgeon general serves a four-year term of office and, depending on whether the current assistant secretary for health is a commissioned corps officer, is either the senior or next most senior uniformed officer of the commissioned corps, holding the rank of a vice admiral. The current surgeon general is Vice Admiral Vivek Murthy.