Health Topic

Opioids and Opioid Use Disorder (OUD)

Opioid use disorder (OUD) a serious public health problem in the U.S. Learn about opioids, how they affect the body, and what OUD is.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Opioid abuse · Opioid addiction · Opioid misuse

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Opioids and Opioid Use Disorder (OUD)

Opioids, sometimes called narcotics, are a type of drug. They include strong prescription pain relievers such as oxycodone, hydrocodone, fentanyl, and tramadol. The illegal drug heroin is also an opioid. Some opioids are made from the opium plant, and others are synthetic (man-made).

A health care provider may give you a prescription opioid to reduce pain after you have had a major injury or surgery. You may get them if you have severe pain from health conditions like cancer. Some providers prescribe them for chronic pain.

Opioids can cause side effects such as drowsiness, mental fog, nausea, and constipation. They may also cause slowed breathing, which can lead to overdose deaths. If someone has signs of an overdose, call 911. These signs may include:

  • Very small pupils of the eyes
  • Falling asleep or loss of consciousness
  • Slow, shallow breathing
  • Choking or gurgling sounds
  • Vomiting
  • Limp body
  • Pale, blue, or cold skin
  • Faint heartbeat
  • Purple lips and fingernails

When using opioids, there is also a risk of opioid use disorder (OUD).

Opioid use disorder (OUD) means that you have a problematic pattern of using opioids. The pattern causes a lot of distress and impairment (meaning that it causes problems in and interferes with your daily life). Instead of OUD, sometimes people use the terms "opioid dependence" and "opioid addiction." Dependence means feeling withdrawal symptoms when not taking the drug. Addiction is a chronic brain disease that causes a person to compulsively seek out drugs, even though they cause harm.

The risk of OUD is higher if you misuse the medicines. Misuse can include taking more than your prescribed dose or taking it more often, using it to get high, or taking someone else's opioids.

Opioid use disorder and overdoses are serious public health problems in the United States. As more people misuse opioids, more women are misusing opioids during pregnancy. This can lead to health risks for the mother and baby. The baby may be born with neonatal abstinence syndrome (NAS). NAS is a group of withdrawal symptoms that a baby has after being exposed to drugs during pregnancy.

Another problem with increased opioid misuse is that it can also lead to more heroin use. There are some people who switch from prescription opioids to heroin because heroin may be cheaper and easier to get.

There are effective medicines to treat OUD. Using medicines to treat OUD is called medications for opioid use disorder (MOUD). MOUD can help you stop using the drug, get through withdrawal, and cope with cravings. It is often combined with behavioral therapy and counseling. Having support from family and friends can also help.

There is also a medicine called naloxone which can treat opioid overdoses. It can reverse the effects of the overdose and prevent death if it is given quickly.

To prevent problems with prescription opioids, be sure to follow your doctor's instructions when taking them. Do not share your medicines with anyone else. Contact your doctor if you have any concerns about taking the medicines.

It sits within Substance Use and Disorders.

The lead U.S. institute for this subject is the National Institute on Drug Abuse.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Opioids and Opioid Use Disorder (OUD)

82 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Treatments and Therapies

Prevention and Risk Factors

Related Issues

Genetics

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Opioid-Related Disorders, Prescription Drug Misuse. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Opioids and Opioid Use Disorder (OUD), a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.