Medically Reviewed

Understanding Opioid Use Disorder (OUD)

8 min read · 7 sections
While prescription opioids are highly effective pain relievers, they—along with illicit and illegally manufactured opioids—can be highly addictive and account for the vast majority of drug overdose deaths.1,2 Learn more about opioids, including types of opioids and their effects and risks, which include misuse, opioid use disorder, and overdose. Also explore symptoms of opioid withdrawal, and discover a host of effective treatment options that can help you or someone you love to break free from opioid addiction and embrace health and wellness in recovery.
What you will learn:
What are opioids, how are they different from opiates, and what are some of the more common types of opioids?
How can medically managed detox help with symptoms of opioid withdrawal?
What is opioid addiction, how is it diagnosed, and what opioid use disorder treatment options are available?

What is an Opioid? 

Opioids are a large class of drugs comprising natural, synthetic, and semi-synthetic substances.3 Some opioids (e.g., tramadol, hydrocodone, and oxycodone) are available via prescription although other opioids are fully or partially illegal.4 For example, while heroin is illegal and has no medically approved use, fentanyl is both available as a prescription for pain as well as manufactured and distributed illegally for recreational and adulterant purposes.5 Opioid medications can also be diverted and purchased illegally.6

Opioids are generally prescribed to treat moderate to severe pain although some prescription opioids are used to treat coughing and diarrhea. Opioids work by reducing the intensity of pain signals reaching the brain. However, opioids also increase dopamine activity in key regions of the brain. This can induce feelings of relaxation and euphoria and can considerably reinforce opioid use and prompt people to repeat the experience.4 

As such, the U.S. Drug Enforcement Administration has categorized several opioids (e.g., oxycodone, fentanyl, hydrocodone, etc.) as Schedule II substances, which are defined as drugs with a high potential for abuse and the ability to lead to severe dependence. Since it has no medically accepted use and a high potential for abuse, heroin is categorized as a Schedule I substance.2 

Unfortunately, opioid misuse is widespread in the U.S. According to data from the 2022 National Survey on Drug Use and Health (NSDUH), among those aged 12 and older, 8.9 million people misused opioids in the past year with the vast majority of these individuals (8.5 million people) misusing prescription pain relievers. Within this same age range, 2.2% (6.1 million people) had an opioid use disorder in the past year.7 

Additionally, opioids are the main drivers of drug overdose fatalities, as they accounted for more than 75% of all overdose deaths in 2021.1 Unfortunately, these statistics are on the rise. Opioid-involved overdose deaths totaled 47,600 in 2017 and remained steady through 2019. However, this figure rose to 68,630 in 2020 and to 80,411 in 2021.8

Specific Opioids and Their Effects

Most prescription opioids—including the following common varieties—are prescribed to treat pain, though some may be used to treat coughing or diarrhea.4

Along with the aforementioned opioids, the drug class includes several additional substances such as fentanyl and heroin.

  • Heroin has no therapeutic use and is used illegally to induce euphoria.2
  • Fentanyl is a synthetic opioid that’s 50 times stronger than heroin and 100 times stronger than morphine. While it’s available as a prescription pain-relief medication, it can also be illegally manufactured and sold, either as a standalone product or added to other substances such as heroin and cocaine. Fentanyl’s potency makes it extremely dangerous, and it’s commonly involved in fatal overdoses.6 

In addition to relieving pain and inducing euphoria, opioids have other potential effects including: relaxation, confusion, nausea, constipation, and slowed breathing.

What is an Opioid Use Disorder (OUD)?

The National Institute on Drug Abuse (NIDA) defines addiction as a chronic, relapsing disease characterized by compulsive drug seeking and use regardless of significant adverse consequences. Just like other chronic diseases such as heart disease or asthma, opioid use disorders can be successfully treated.9 

Symptoms and Diagnosis

When it comes to opioid use disorder symptoms and diagnosis, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) indicates that an opioid use disorder is a problematic pattern of opioid use leading to clinically significant impairment or distress manifested by at least two of the following criteria within a 12-month period:10

  • Taking opioids for longer periods of time or in larger amounts than intended.
  • Being unable to cut down or stop substance use.
  • Spending a lot of time obtaining, using, and recovering from the effects of opioids.
  • Experiencing cravings or intense desires or urges for opioids.
  • Failing to fulfill obligations at home, work, or school due to opioid use.
  • Continuing opioid use despite having interpersonal or social problems that are caused or worsened by opioid use.
  • Giving up social, recreational, or occupational activities due to opioid use.
  • Using opioids in physically dangerous situations.
  • Continuing opioid use despite knowing that a physical or psychological problem is probably caused or worsened by opioids.
  • Developing tolerance, i.e., a markedly diminished effect with continued use of the same amount of an opioid or needing more of an opioid to achieve previous effects.*
  • Experiencing withdrawal, manifested by unpleasant opioid withdrawal symptoms when you reduce your dose or stop using the opioid, or taking opioids to relieve or avoid withdrawal symptoms.*

*These criteria should not be considered met in those solely taking an opioid therapeutically under appropriate medical supervision.

Recognizing Opioid Misuse

Opioid misuse can involve:4 

  • Taking an opioid to get high.
  • Taking someone else’s prescription opioid.
  • Taking the opioid in a dose other than prescribed.
  • Taking an opioid by a route other than prescribed (such as snorting or injecting).
  • Using heroin or illicitly manufactured fentanyl.

Risks Associated with Opioid Misuse

Opioid use disorder and respiratory depression/overdose are associated with opioid misuse.4,11 Additionally, those who inject opioids are at risk of contracting various blood-borne viruses such as HIV and hepatitis B and C—and of developing injection-related health conditions. Transmission via contact with blood or other bodily fluids can occur when individuals share needles and related injection equipment.12

Smoking and snorting opioids are also linked to conditions involving the lungs, nasal passages, and more.13,14 And use of opioids during pregnancy is associated with neonatal abstinence syndrome in infants.4

Overdose and Its Consequences

When illicit or prescription opioids overwhelm the brain and interrupt the body’s ability to breathe normally, it can lead to an overdose, which can be fatal.15,16 

Symptoms of an opioid overdose include:15

  • Small, constricted “pinpoint” pupils.
  • Difficulty remaining awake or loss of consciousness.
  • Slowed, shallow, or stopped breathing.
  • Choking or gurgling sounds.
  • Limp body.
  • Pale, blue, or cold skin.

Mixing an opioid—including both illicit and prescription varieties—with other opioids or central nervous system (CNS) depressants such as alcohol or benzodiazepines can increase the risk of overdose, damage to the brain and other organs, and death.17 

If you suspect someone is experiencing an overdose, the Centers for Disease Control and Prevention (CDC) provides the following guidance:17

  • Call 911 immediately.
  • Administer naloxone* if available.
  • Attempt to keep the individual awake and breathing.
  • Position the individual on their side to prevent them from choking on vomit.
  • Stay with the person until emergency responders arrive.

*Naloxone—which is available via brands such as Narcan, Kloxxado, and RiVive—is a life-saving medication that can rapidly reverse the effects of opioid overdose and restore a person’s breathing. However, naloxone must be administered quickly, and its effects are temporary. Thus, it’s important to seek immediate medical attention even after naloxone is given.18 

How is Opioid Use Disorder Treated?

Addiction treatment programs and opioid treatment programs are available to treat people with opioid use disorder. Customized to meet the needs of each individual, treatment for opioid use disorders often begins with detox (as described below) and is followed by inpatient or outpatient treatment as well as continuing care or aftercare to support ongoing recovery management.19 

Detox and Withdrawal

Chronic opioid use can lead to physiological dependence, even with prescribed opioids. Dependence is characterized by the presence of withdrawal symptoms when substance use is stopped or significantly reduced.20 

Symptoms and signs of opioid withdrawal vary in their appearance and severity based on a host of factors, such as the length of use, interval between doses, quantity taken, a person’s individual health factors, etc. However, opioid withdrawal typically involves three or more of the following symptoms:21

  • Feelings of unhappiness (e.g., anger, guilt, failure) and dissatisfaction/discontent.
  • Insomnia.
  • Enlarged pupils.
  • Nausea, vomiting.
  • Diarrhea.
  • Bone and muscle pain.
  • Fever.
  • Sweating.
  • Goosebumps.
  • Tearing.
  • Yawning.
  • Runny nose.

While opioid withdrawal is rarely life-threatening, symptoms can be uncomfortable and may be severe.21 Plus, some people who want to stop opioid use may be so fearful of withdrawal symptoms or unable to tolerate them that they return to opioid use. Stopping opioids and restarting them at the same dose after a period of withdrawal can result in overdose, due to lowered tolerance.22,23 

However, medically assisted detox can help to ensure patients are as safe and as comfortable as possible during opioid withdrawal and can assist them in proceeding safely and seamlessly into treatment. Opioid detox centers can provide not only a safe and compassionate environment with care and monitoring but also access to medications (e.g., methadone, buprenorphine, etc.) specifically designed to treat opioid withdrawal and opioid use disorders. Plus, medically managed detox can provide supportive measures to better manage withdrawal symptoms—via physical and emotional support, pain management, adequate nutrition, etc.16

While detox and medications for opioid use disorder are important steps on the road to recovery, they’re just one part of a multipart treatment process. Some form of inpatient or outpatient treatment as well as aftercare are best practice following detox.19

Rehabilitation and Recovery

Treatment for opioid use disorders isn’t a one-size-fits-all solution. Rather, care plans are customized to the unique needs of each individual. That said, opioid addiction treatment typically involves behavioral therapies, medication for opioid use disorder, educational insights, peer and professional support, and individual, group, and family counseling.19 

Following medically managed detox (as described above), treatment options are organized into the following levels of care.19

Aftercare or continuing care can support ongoing recovery management following more formalized inpatient and outpatient programs. Aftercare can include sober living facilities, ongoing therapy, attending meetings run by 12-Step programs, and more. 

If you or someone you love is struggling with an opioid use disorder, help and hope are available. Offering accredited facilities and staff paired with evidence-based treatment, American Addiction Centers (AAC) offers the full spectrum of care via multiple U.S. treatment centers, which are in-network with myriad insurance providers that typically cover part of treatment costs. 

Available 24/7 for a free and confidential conversation, admissions navigators at can help you explore various opioid use disorder treatment options and facilities. However, they can also answer your treatment questions, discuss financing and payment options, and more. Additionally, staff can verify any insurance benefits, or you can verify your insurance benefits online. And if you’re not ready to talk, you can sign up for text communications.

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