What is a substance use disorder (SUD)?

There are three different terms used to define substance-related disorders, including the following:

  • Substance abuse is used to describe a pattern of substance (drug) use leading to significant problems or distress such as failure to attend work/school, substance use in dangerous situations (driving a car), substance-related legal problems, or continued substance use that interferes with friendships and or family relationships. Substance use, as a disorder, refers to the abuse of illegal substances or the abusive use of legal substances. Alcohol is the most common legal drug of abuse.
  • Substance dependence is used to describe continued use of drugs or alcohol, even when significant problems related to their use have developed. Signs include an increased tolerance or need for increased amounts of substance to attain the desired effect, withdrawal symptoms with decreased use, unsuccessful efforts to decrease use, increased time spent in activities to obtain substances, withdrawal from social and recreational activities, and continued use of substance even with awareness of physical or psychological problems encountered by extent of substance use. chemical dependence
  • Chemical dependence is also used to describe the compulsive use of chemicals (drugs or alcohol) and the inability to stop using them despite all the problems caused by their use.

Substance use disorders (SUDs) occur when the recurrent use of alcohol and/or drugs causes clinically significant impairment, including health problems, disability and failure to meet major responsibilities at work, school or home. Addiction is a complex disease, and quitting usually takes more than good intentions or a strong will. Drugs change the brain in ways that make quitting hard, even for those who want to.

Awareness about the scope of SUD and the physical, mental, emotional and spiritual toll it takes is one component, along with prevention and treatment to improve the lives of affected individuals.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified health care provider.

Robert Rozsay
Addiction Medicine Specialist

Why try to complicate the answer. The dictionary explains it clearly:

  • Abuse: Use (something) to bad effect or for a bad purpose, make excessive and habitual use of (alcohol or drugs, esp. illegal ones).
  • Dependence: The state of relying on or being controlled by someone or something else.
Fredrick Wade
Addiction Medicine Specialist

It is the development of a primary relationship with a mind altering substance. This relationship is based on a thinking error which is an outgrowth of the developing belief that the substance solves all life's problems.  As reliance on the substane to manage life continues to grow so does the the capacity for psychological and physiological dependence grow as well. The skewed experience that life or feelings states are made better (or become more manageable) by the use of the substance is a poweful and reinforcing aspect of developing a primary substance use disorder. Such disorders are typically characterized by continued use despite negatvie consequences, diminshed social, occupational or recreatiional activities, requring more over longer periods of time, tolerance which ask that one use more to achieve desired effect, substance taken to avoid withdrawal symptoms, large amount of time is devotd to the getting and using of the substance.

Dr. Howard J. Shaffer, PhD
Addiction Medicine Specialist

Substance abuse is the term the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) uses for people who have a less severe relationship with their object of addiction than those with dependence. Unlike those who are dependent on substances, people who abuse substances don't have the same compulsion or physical need to use, but they do use excessively on an inconsistent or regular basis. People who abuse might do so to help themselves cope with emotional problems and life crises.

While substance abuse differs from substance dependence, the difference might be a matter of degree. People who abuse substances and those who are substance dependent can experience many of the same problems.

The DSM-IV defines substance abuse as use that produces one or more of the following situations within a year:

  • repeatedly failing to fulfill major work, school, or home responsibilities (for example, regularly missing school or performing poorly at work because of substance use)
  • using the substance in situations where it's physically dangerous to do so, such as while driving a car, boating, or operating machinery
  • recurring substance-related legal problems, such as arrests for driving while intoxicated, disorderly conduct, or damaging property while intoxicated
  • continued substance use despite ongoing relationship problems either caused worsened by substance use (for example, arguing with a spouse about the effects of substance use).

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.