What Is Opioid Use Disorder?

Opioid use disorder (OUD) is a condition that can affect anyone who uses opioid drugs. It can develop when people use opioids in ways that are unsafe, even if a doctor originally prescribed them.^1-3

Opioid use disorder is a chronic medical condition that involves changes in the brain as well as behavior. People with OUD may have:^1-3

• A strong urge to use opioids
• Difficulty controlling their use of opioids
• Continued use of opioids despite negative consequences
• Physical dependence on opioids

OUD can cause serious health consequences, like disability, overdose, and even death, if not treated. With the right support and treatment, people can manage and recover from this condition.^2-4

How does OUD affect the brain?

Opioids flood the brain with dopamine, a chemical that creates feelings of pleasure and reinforces drug use. Over time, the brain becomes less sensitive to natural rewards, making it harder to feel pleasure from everyday activities.⁵

The brain also adapts to the presence of opioids, requiring higher doses to achieve the same effect (tolerance) and causing withdrawal symptoms when the drug is absent. These changes make it hard to stop using opioids, as the brain prioritizes drug-seeking over other needs.⁵

Opioid dependence vs. opioid addiction

A few terms relating to opioid use disorder may need explanation. These terms include “dependence” and “addiction.”¹

Opioid dependence

Dependence happens when your body gets used to having opioids in your system. Over time, you may need more of the drug to get the same effect. This is known as building up a “tolerance.”^1-3

If you suddenly stop taking opioids, you may have withdrawal symptoms. This is because your body has become dependent on the drug. Withdrawal symptoms can include:^1-3

• Nausea
• Diarrhea
• Runny nose
• Sweating
• Chills
• Muscle pain

Being physically dependent on opioids does not always mean you have OUD. For example, some people who take opioids for chronic pain may become dependent on the medicine to manage their pain. But they may not be addicted to it, especially if they use it as prescribed by their doctor.¹

Opioid addiction

Addiction is different from dependence. A person with an addiction has a very hard time stopping using the drug, even if it is harming their life. While dependence involves a physical reaction to the drug, addiction involves this physical aspect as well as a behavioral aspect.^1-3

People with opioid addiction may crave the drug so strongly that they cannot think about anything else. They might use opioids even when it is dangerous, such as while driving or taking care of children. The use of opioids can even take precedence over activities necessary for daily living such as work, school, and grooming. Addiction is often linked to changes in the brain that affect decision-making and self-control.^1-3

To sum up, a person can be dependent on opioids without being addicted. Addiction usually includes physical dependence on the drugs as well as a psychological need.¹

How common is opioid use disorder?

Opioid use disorder is a serious public health issue. It is so serious that a nationwide US Public Health Emergency was declared in 2017. The opioid crisis affects people from all walks of life, including teenagers, adults, and older people. The following statistics show how widespread it is:^1,2,4,6

• OUD affects more than 20 million people worldwide and 3 million people in the United States.
• Each year, more than 120,000 deaths are linked to opioids – 81,000 of those occurred in the US in 2022.
• Opioids account for the most drug-related deaths in the US.
• Synthetic opioids like fentanyl are now responsible for nearly 90 percent of opioid-related deaths in the US.

Types of opioids and narcotics

Opioids are a class of drugs that includes both prescription medicines and illegal drugs. These substances work by binding to opioid receptors in the brain. This helps relieve pain and also creates feelings of pleasure and euphoria. The resulting “high” is one reason why people misuse opioids. Opioids can slow down breathing, heart rate, and blood pressure, sometimes to dangerously low levels.^1-4

Here are some of the most common types of opioids.

Prescription opioids

Doctors may prescribe opioids to treat moderate to severe pain, such as after surgery or a serious injury. Prescription opioids include:^1,2,4

• Oxycodone (OxyContin®, Percocet®)
• Hydrocodone (Vicodin®)
• Morphine (MS Contin®)
• Codeine
• Fentanyl (Actiq®, Duragesic®, Fentora®)

Heroin

Heroin is an illegal recreational opioid drug. It is highly addictive and has no accepted medical use. People who use heroin are at high risk of overdose, especially if it is mixed with other substances. And it is hard to know whether it is mixed with another substance when they take it.^1,2,4

Synthetic opioids

Synthetic opioids include fentanyl and carfentanil. These are human-made drugs that are much stronger than natural opioids like morphine. Synthetic opioids may be prescribed to treat severe pain after surgery or in people with cancer who are at the end of their lives. Unfortunately, they are also made and sold illegally.^4,7

Because of their strength, synthetic opioids are very dangerous. Fentanyl is up to 50 times stronger than heroin and 100 times stronger than morphine. Carfentanil is 10,000 times stronger than morphine and 100 times stronger than fentanyl. Just a tiny amount of this drug can lead to an overdose and death when ingested.^4,7

The rise of adulterants and emerging street drugs

In recent years, many street drugs have been found to contain substances other than what they are sold as. These substances are called “adulterants” or “cutting agents.” They often make the drugs even more dangerous.⁸

Why are adulterants added?

Adulterants are added to drugs like heroin and cocaine to increase the amount of the drug or to make the drug stronger. But these adulterants are often extremely toxic and dangerous. And when added to already strong opioids, they increase the risk of overdose and death.⁸

Emerging drugs to be aware of

New drugs are showing up on the streets that are less well known but carry serious risks. These are mind-altering drugs that can be very dangerous. Most people are totally unaware that they are consuming these new drugs. This is because the drugs are often marketed as something else or mixed with other drugs.^9-11

Some new street drugs include:^9-12

• Nitazene (or “ISO”) – This is a new synthetic opioid that may be more powerful than fentanyl. It was first identified in 2019 and has been spreading across the country since then. It comes in pill and powder form. ISO may be mixed with heroin and fentanyl and increases the risk of overdose deaths.
• “Rainbow fentanyl” – This brightly colored type of fentanyl looks like candy and comes in pill, powder, or block form. Authorities believe it is produced in this way to be marketed to children and young people.
• Tianeptine – This is an antidepressant drug that is sometimes used to treat anxiety and depression. However, if used in large amounts, it can lead to some of the side effects that are common to opioids (drop in blood pressure, heart rate, breathing). So, it can be dangerous.
• Xylazine (“tranq”) – This is a veterinary tranquilizer that is used in animals. It is not approved for human use. But it is increasingly found mixed with illicit drugs like fentanyl and heroin. It can cause a person’s breathing, heart rate, and blood pressure to all slow down to dangerous levels, which increases the risk of overdose.

Understanding and addressing OUD

Opioid use disorder is a very complex condition. But there are effective treatments available. Medicines, counseling, and therapy are all available treatments for anyone living with OUD. Many people who receive treatment for OUD can regain control of their lives and find a path to recovery.^1,2

If you or someone you know is living with OUD, help is available. Call the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-HELP (4357) for free, 24/7 confidential support.¹³