What are opioids?

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

Opioids can:

  • Reduce pain by blocking pain messages,
  • Make someone feel relaxed or sleepy,
  • Cause euphoria  (make a person feel really good),
  • Slow or stop breathing.

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.
Title slide from video

Susan’s Brain: The Science of Addiction, a video from Harvard and National Geographic describes what happens in the brain when someone takes opioids. (Content warning: this video contains a depiction of someone falling from a bicycle and breaking their wrist, which may be upsetting for some viewers.)

What is opioid use disorder?

Opioid use disorder (OUD) is a medical condition. People with the condition are physically dependent on opioids and have brain changes that affect their thinking, priorities and relationships.

For some people, when they initially try opioids they feel really good. Over time their body will adapt to these external opioids by changing the responsiveness of opioid receptors. The neurotransmitter related to feeling pleasure, dopamine, is also impacted when opioids are used. 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. 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.

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

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 can improve your health.

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. Nearly one in four people who try heroin develop opioid use disorder; this proportion may be similar for people who try other types of opioids in the social context and with the mindset of trying “to get high.”

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; others feel sleepy or nauseated.

Health risks of untreated opioid use disorder

People with untreated opioid use disorder are at elevated risk for dying, including being at high risk from an opioid overdose. They are also more likely to get serious infections like hepatitis C and HIV.