Substance use disorder is a form of substance-related disorder in which a person’s use of a substance leads to physical, mental, or social harm. This can include:

• Risky use of drugs and alcohol — such as drinking before driving
• Drug addiction — when the drug causes compulsive behavior that users cannot control
• Alcohol addiction — when drinking causes compulsive behavior that users cannot control
• Dangerous use of prescription drugs (legal or illegal)
• Over-the-counter drug abuse.

Substance abuse is often used as a blanket term to include substance dependence and substance abuse disorder. Many people believe that you either have one or the other, but there are actually four combinations of these terms. Substance abuse can be either a one-time activity or chronic behavior.

Substance dependence is diagnosed when three or more of the following symptoms are present within a single year:

• Tolerance (needing larger doses to get the same effect)
• Withdrawal symptoms
• Drug-seeking behavior to obtain the substance (doctor shopping, stealing)
• Spending a lot of time getting, using, or recovering from the effects of the drug
• Decreased participation in important social, occupational, or recreational activities because of the drug
• Continued use of the drug despite knowing it is causing a physical or psychological problem
• Substance abuse disorder is diagnosed when two or more of the following symptoms within a single year:
• Failure to fulfill responsibilities at work, school, or home as a result of substance use
• Continued use despite having social or interpersonal problems because of the drug (fights, accidents)
• Unable to cut down or stop using the drug
• Using more of the drug over time
• Legal problems as a result of having used the drug.

Patients with substance abuse require comprehensive treatment, but many are unaware that they have a problem.