This page provides information on:

  • What are opioids?
  • What is opioid use disorder?
  • Why do people get opioid use disorder?
  • Health and opioid use disorder

What are opioids?

Opioids are a class of drugs that act on the endorphin system, which helps manage pain and pleasure.

Opioids include medications, like hydrocodone and oxycodone, and non-prescription drugs like heroin and illicit fentanyl products. For more examples of opioids check out NIDA’s page on opioids.

Opioids can cause:

  • Tolerance: over time you to need more to have the same effect.
  • Physical dependence: when you stop using you go into withdrawal. Opioid withdrawal can feel like a very bad flu and can include nausea, chills, diarrhea, vomiting, and anxiety.
  • Overdose: more opioids than the body can handle, breathing slows or stops.
  • Opioid use disorder (OUD): also called addiction, this is physical dependence along with thinking/psychological and social problems.

Learn more about opioids from the CDC.

Susan's Brain, the science of addiction

Susan’s Brain: The Science of Addiction, a video from Harvard and National Geographic describes what happens in the brain when someone takes opioids.

What is opioid use disorder?

Opioid use disorder (OUD) is a medical condition. If you have OUD it means you are physically dependent on opioids and have brain changes that affect your thinking, priorities and relationships.

Opioid use disorder is:

  • Biological: physical dependence, tolerance, and withdrawal.
  • Psychological: compulsive use, always thinking about opioids, most important thing in life.
  • Social: opioids get in the way of responsibilities, relationships, work, school, etc.

Opioid use disorder is a medical condition that can be long-term, like diabetes, high blood pressure, or depression. Like those health conditions, medications, behavior change, counseling and other supports can improve your health.

OUD can come back if not treated properly. You may need to try more than one type of treatment to find what works best for you

Signs and symptoms

People with opioid use disorder:

  • Keep using opioids even though they know it is hurting them,
  • Can’t quit even when they try repeatedly,
  • Spend lots of time using opioids, or recovering from using,
  • Use opioids in dangerous situations,
  • The formal diagnosis of OUD involves these behaviors.

Read more about the official diagnosis of OUD.

Why do people get opioid use disorder?

Most people who try opioids will not develop opioid use disorder. About one in four people who try heroin develop opioid use disorder.

Whether or not someone who tries opioids develops opioid use disorder can be influenced by their genetics, personality, physical/emotional trauma, life history, social environment, and other factors.

For some people, the first time they try opioids, they feel really good, some even say “normal”; others feel sleepy or nauseated. Over time when taken repeatedly the body gets used to opioids, and when a person does not have external opioids in their system, they will have symptoms of withdrawal and feel really bad. People will continue to use opioids just to feel normal or not “sick”.

Medications like methadone and buprenorphine can help people stabilize and avoid withdrawal by binding to opioid receptors where they have a full or partial opioid effect.

Health and opioid use disorder

If you have untreated opioid use disorder you are at higher risk for dying, including being at high risk from an opioid overdose. You are also more likely to get serious infections like hepatitis C and HIV. If you think you might have opioid use disorder, talk to your health care provider. They can help you stay healthy even if you’re not ready for medications or other treatment.

If you’re ready to learn about treatment, visit this page on treatment for opioid use disorder and this page for information on counseling and recovery supports.