Substance abuse is the overindulgence in and dependence of a drug or other chemical leading to effects that are detrimental to the individual's physical and mental health, or the welfare of others.

The disorder is characterized by a pattern of continued pathological use of a medication, non-medically indicated drug or toxin, that results in repeated adverse social consequences related to drug use, such as failure to meet work, family, or school obligations, interpersonal conflicts, or legal problems. There are on-going debates as to the exact distinctions between substance abuse and substance dependence, but current practice standard distinguishes between the two by defining substance dependence in terms of physiological and behavioral symptoms of substance use, and substance abuse in terms of the social consequences of substance use.

Substance abuse may lead to addiction or substance dependence. Medically, physiologic dependence requires the development of tolerance leading to withdrawal symptoms. Both abuse and dependence are distinct from addiction which involves a compulsion to continue using the substance despite the negative consequences, and may or may not involve chemical dependency. Dependence almost always implies abuse, but abuse frequently occurs without dependence, particularly when an individual first begins to abuse a substance. Dependence involves physiological processes while substance abuse reflects a complex interaction between the individual, the abused substance and society.

Distinct from the concept of drug abuse:

Substance abuse is sometimes used as a synonym for drug abuse, drug addiction, and chemical dependency, but actually refers to the use of substances in a manner outside sociocultural conventions. All use of illicit drugs and all use of licit drugs in a manner not dictated by convention (e.g. according to physician's orders or societal norms) is abuse according to this definition, however there is no universally accepted definition of substance abuse.

The physical harm for twenty drugs was compared in an article in the Lancet, with the results shown in the diagram. Physical harm was assigned a value from 0 to 3 for acute harm, chronic harm and intravenous harm. Shown is the mean physical harm. Not shown, but also evaluated, was the social harm.

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Author's Bio: 

This definition is part of a series that covers the topic of Substance Abuse. The Official Guide to Substance Abuse is Scott M. Davis.

Inpatient Medical Director for the world-renowned Betty Ford Center Certified in Addiction Medicine. Fellow of the American Society of Addiction Medicine Expertise in Internal Medicine Certified Medical Review Officer, with expertise in detection and analysis of all drugs of abuse. Nationally recognized authority in Addiction Medicine and opiate detoxification by numerous state and federal agencies, including the Center for Substance Abuse Treatment (CSAT) and the National Institute of Drug Abuse (NIDA).

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