Merck Manual

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Substance Use Disorders


The Manual's Editorial Staff

Last full review/revision May 2019| Content last modified May 2019
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What are substance use disorders?

The use of some substances causes feelings of pleasure. The pleasure makes you want to keep using the substance. The substances can be legal drugs such as alcohol and tobacco, illegal drugs, or prescription drugs. Some people are able to get prescription drugs, such as opioids, illegally.

A substance use disorder is when you keep using a substance even though using it causes you problems at home or at work.

  • People with a substance use disorder aren't able to control their use of the substance

  • A substance use disorder can happen with legal or illegal substances

  • There's no specific personality type that's more likely to get a substance use disorder

  • Using a substance doesn’t always mean you have a substance use disorder

  • Doctors treat these disorders with counseling and sometimes medicine

What's drug addiction?

Drug addiction, drug abuse, and similar terms have become very judgmental. The terms also aren't very specific. That's why doctors prefer the term "substance use disorder" for when people can't stop using substances that harm them.

What causes a substance use disorder?

Not everyone who uses a substance has a substance use disorder. Although almost anyone can develop a substance use disorder, your risk is greater if:

  • The substance is very pleasurable and easy to get

  • You don't believe the substance is that dangerous

  • You often feel sad, lonely, or anxious

  • You have certain psychiatric disorders, such as some personality disorders or major depression

  • Your family members or friends use substances (this is especially true for adolescents)

Your risk also is increased if you take prescription opioid painkillers for a painful injury or chronic pain. Opioids, though a legitimate way to control pain, are highly addictive.

What are the symptoms of a substance use disorder?

With a substance use disorder, you may:

  • Not be able to control use of the substance: You take it even when you know it's bad for you

  • Have tolerance to the substance: You need to use more and more of it to get the same effect

  • Experience withdrawal: You get unpleasant symptoms when you stop using the substance

How can doctors tell if someone has a substance use disorder?

Sometimes people tell their doctor they're having a problem. Or doctors may suspect you have a substance use disorder if you:

  • Spend a lot of time getting, using, or recovering from the effects of the substance

  • Want to stop using the substance but can't

  • Have a strong craving to use the substance

  • Can't meet your responsibilities at work, school, or home because of the substance

  • Use the substance in dangerous situations, such as when driving

  • Give up social or work activities because of the substance

Tolerance and withdrawal also are signs of substance use disorder, unless they develop while you're using the substance legitimately. For example, you may have opioid withdrawal after taking opioids for less than a week, which may be necessary for certain painful injuries, such as severe burns.

Although urine and blood drug tests can tell if you have drugs in your system, they can't tell if you have a substance use disorder.

How do doctors treat substance use disorders?

Treatment depends on the substance. Doctors may treat substance use disorders using:

  • Counseling

  • Family support

  • Support groups

  • Medicines

Specific substance use disorders, for example alcohol use disorder and opioid use disorder, have different treatments.

Where can I get more information about substance use disorders?

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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