Opioids

Overview

Opioids are a class of natural, semi-synthetic, and synthetic drugs. Opioids include both prescription medicines used to treat pain and illegal drugs like heroin. Opioids are addictive.

• Natural opioids such as morphine, codeine, opium, and thebaine come from the seed pods of the opium poppy plant.
• Semi-synthetic opioids, such as heroin and pain relievers oxycodone, hydrocodone, and oxymorphone, are made in laboratories by chemically processing natural opioids.
• Synthetic opioids, such as fentanyl, are manufactured entirely in laboratories with no natural ingredients.

Opioids differ in their strength, or potency. For example, fentanyl is 50 to 100 times more potent than morphine. This means that even small doses of fentanyl can be fatal. Fentanyl can be even more dangerous when it is mixed with other drugs. This can happen without the knowledge of the person taking them.

Prescription opioids are used mostly to treat moderate to severe pain, though some can also treat coughing and diarrhea. Common prescription opioids include hydrocodone, oxycodone, oxymorphone, morphine, codeine, and fentanyl. 

Pharmaceutical fentanyl is used in medical settings for surgery and certain types of severe pain. Fentanyl is also made illegally, and most fentanyl-related overdose deaths in the United States involve illegally made fentanyl, which may be mixed into other drugs without a person's knowledge.

How Do Opioids Work?

After they are taken, opioids enter the bloodstream and travel through the body and to the brain. They bind to specific molecules called opioid receptors on certain nerve cells in the brain, the spinal cord, and throughout the body.

These receptors normally interact with naturally occurring molecules in the body to regulate essential functions. They help control pain, regulate breathing (respiration), and help with stress responses. For example, opioid receptors are found on nerve cells that send pain signals from the body to the brain. When opioid drugs bind to these receptors, they trigger changes in nerve cells that can reduce the transmission of pain signals in the spinal cord. They also dull the perception of pain in the brain. That’s why opioids are effective pain medicines.

Opioid receptors are also found in parts of the brain involved in reward. The body makes its own opioid-like chemicals that act on these receptors. In response to natural rewards, such as food and social interaction, these brain systems can make us feel good and motivate us to repeat behaviors that are important for our well-being and survival. Opioid drugs can activate some of the same brain systems, producing pleasurable effects that can make repeated drug use more likely.

Opioids and the Overdose Crisis

Use of opioids, either by themselves or in combination with other drugs, is a major driver of the drug overdose crisis in the United States. Most overdose deaths in recent years have involved synthetic opioids, primarily illegally made fentanyl. Illegally made fentanyl may be mixed with other drugs or pressed into counterfeit pills without a person knowing it.

Effects of Opioids

Short-Term Effects

Opioids can relieve pain and make people feel relaxed and happy. They can also cause changes in thinking, including difficulty concentrating or making decisions. How soon these effects begin depends on the opioid used and how it is taken. For example, fentanyl acts faster than morphine, and opioids act faster when injected or inhaled than when taken by mouth.

Other short-term effects include:

• Drowsiness
• Confusion
• Nausea
• Constipation
• Euphoria
• Slowed breathing

Taking too high a dose of opioids, or taking opioids over longer periods of time, can lead to harmful or even deadly effects.

Opioid Overdose

An opioid overdose occurs when a person takes a higher drug dose than their body can handle. Opioids can slow breathing to life-threatening levels. As a result, not enough oxygen reaches the brain. This can cause severe brain damage or death.

Several signs can indicate that a person is experiencing an overdose and needs immediate medical attention:

• Unconsciousness or inability to wake up
• Slow or shallow breathing, or difficulty breathing
• Discolored, purplish, gray, or pale skin — especially the nails or lips
• Small, constricted “pinpoint” pupils that don’t react to light
• Limp body
• Vomiting or gurgling noises
• Faint heartbeat
• Inability to speak

People can overdose without knowing that they have taken dangerously high opioid doses. For example, deadly doses of illicit fentanyl can be mixed into or sold as other drugs, such as heroin, cocaine, or counterfeit pills.

See the Emergency Information section at the top of the page for what to do in case of an overdose.

Certain factors increase the risk of opioid overdose:

Fentanyl

Fentanyl is 50 to 100 times more potent than morphine. Because it is so potent, very small amounts can cause a life-threatening overdose. Illegally made fentanyl is especially dangerous because it may be mixed with other drugs - sometimes without the knowledge of the person taking them. Illegally made fentanyl may be mixed with drugs such as heroin, cocaine, or methamphetamine, increasing the risk of overdose. Some counterfeit pills may contain fentanyl as well, such as those made to look like prescription medicines used to treat anxiety or attention-deficit/hyperactivity disorder (ADHD). These fake pills are often sold through social media or internet sites, and people taking them often do not know they contain fentanyl.

Using Opioids for Dental Pain

Filling an opioid prescription after a dental procedure has been associated with a higher risk of overdose in patients and their family members. For many teens and young adults, first exposure to opioids often happens after wisdom-tooth removal.

Risks of Opioid Use When Combined with Use of Other Drugs

Taking opioids with certain other drugs or substances can increase the risk of serious harm. Combining opioids with benzodiazepines (a type of prescription commonly prescribed for anxiety or insomnia) or alcohol can increase the risk of overdose because all of these substances slow activity in the brain and nervous system.  Together, they can cause extreme drowsiness and dangerously slow breathing.

Opioid Withdrawal Symptoms

If a person stops taking an opioid, they may experience withdrawal symptoms. These can begin as early as a few hours after the last dose. Symptoms include:

• Muscle and bone pain
• Sleep problems
• Diarrhea and vomiting
• Cold flashes with goose bumps
• Uncontrollable leg movements
• Severe cravings
• Abdominal cramps
• Agitation and anxiety
• Chills

These symptoms can be extremely uncomfortable and are a major reason many people find it so difficult to stop using opioids.

Opioid Use Disorder and Addiction

Repeated misuse of opioids can lead to a substance use disorder, a medical condition that ranges from mild to severe. Addiction is the most severe form of substance use disorder. Drug addiction is a chronic disease characterized by compulsive, or uncontrollable, drug seeking and use despite harmful consequences.

When a person takes opioids repeatedly, their body may adapt to the presence of the drug. Over time, they may need a larger dose or more frequent doses to achieve the same effect — this is known as tolerance. If use is stopped or reduced suddenly, they may experience withdrawal symptoms such as restlessness, nausea, or anxiety. Tolerance and withdrawal can occur in anyone who takes opioids regularly, including people managing chronic pain, and do not on their own indicate addiction.

Health professionals diagnose opioid use disorder based on criteria established in the DSM5-TR, including being unable to control opioid use, continuing to use despite serious negative consequences, or giving up important activities because of use - not just tolerance and withdrawal.

Related Health Effects

Cardiovascular Risk

Depending on the dose and other factors, opioids can slow the heart rate and lower blood pressure. In a severe overdose, breathing can stop, which can lead to cardiac arrest.

Immune System Risk

Opioids can impair the immune system, increasing the risk of infection.

Effects on Pain Sensitivity

Opioid use, particularly in high doses or for a long period of time, can cause changes in a person’s body that can actually make them more sensitive to pain. When using opioids to treat acute or chronic pain, these potential risks may need to be weighed against the health risks associated with untreated or under-treated pain.

Mental Health and Sexual Health Risks

Opioid use has been associated with mental health conditions like depression and sexual dysfunction.

Infectious Disease Risk

Injecting opioids can increase the risk of infectious diseases, particularly when needles, syringes, or other injection equipment are shared or reused. Sharing contaminated injection equipment can transmit bloodborne infections such as human immunodeficiency virus (HIV) and hepatitis C. Injecting drugs can also introduce bacteria into the bloodstream and cause serious infections, including infective endocarditis, an infection of the heart’s inner lining or valves. Opioid use can also be associated with behaviors that increase the risk of HIV and other sexually transmitted infections, such as sex without condoms.

Populations With Increased Health Risk Related to Opioids

Adolescence

Adolescence is an important period for preventing opioid misuse. Misuse of prescription opioids and use of illicit opioids during this time can increase the risk of overdose and developing opioid use disorder. Learn more about substance use in youth and young adults. 

Pregnancy

Opioid use during pregnancy can increase the risk of serious complications for both the pregnant woman and the baby. Babies exposed to opioids for an extended period before birth may develop neonatal opioid withdrawal syndrome (NOWS) after birth. Symptoms can include irritability, excessive crying, tremors, and difficulty feeding. Opioid use disorder during pregnancy has also been linked to poor fetal growth, preterm birth, stillbirth, and other serious health problems. Treatment during pregnancy can improve outcomes (see Treatment section below).

Older Adults

Older adults may be at greater risk of opioid-related harms because they are more likely to have multiple health conditions, take multiple medications, and experience age-related changes that can affect how the body processes drugs.

Prevention Guidance

Safe Use of Prescribed Opioids

When opioids are prescribed, there are steps you can take to reduce risk of harm:

• Tell your doctor or dentist about all other medicines you are currently taking, and whether you or others in your family have had any problems with substance use.
• Ask if the medicines are necessary and about the risks of taking them.
• Ask how to take the medicine and how long you should take it.
• Take the medicine exactly according to the directions you have received.
• Never use alcohol when taking an opioid medicine.
• Store the medicine in a safe place out of sight and out of reach of children, teens, and guests — preferably in a locked cabinet.
• Dispose of any unused or expired medicine as soon as possible.
• If you want to reduce or stop taking opioids, talk with your doctor or healthcare provider. They can help you taper safely and manage withdrawal symptoms. Do not stop opioids suddenly without medical guidance.

Non-Opioid Alternatives for Dental Pain

Over-the-counter, non-opioid medicines (such as acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen), can be just as or more effective for managing most dental pain. They also have fewer side effects and a lower likelihood of harm. Talk with your dentist about which medicines may be right for you.

Combining Opioids with Benzodiazepines or Alcohol

People being prescribed any medicine should tell their healthcare team about all other substances and medicines they use and consult with them about avoiding or managing the risks of using certain medicines and substances in combination. Any combination of alcohol, opioids, and benzodiazepines is particularly dangerous because these substances can increase sedation and slow breathing. Using them together increases the risk of overdose.

Reducing Risks Associated with Opioid Use

• Take prescription opioids only as prescribed, and never take someone else's medication.
• If you use illicit opioids, carry naloxone (see below).
• If you use illicit opioids or drugs that may contain fentanyl, avoid using alone.
• Go slow, in terms of amount and speed that the drug is taken.
• Use fentanyl test strips to check nonprescribed drugs. Avoid drugs that test positive, and remember that a negative test does not mean a drug is safe.
• If you inject drugs, use sterile injection equipment and syringe services programs when available. Never share needles or other injection equipment.

Naloxone is a medicine that rapidly reverses an opioid overdose. Naloxone can quickly restore normal breathing to a person if their breathing has slowed or stopped because of an opioid overdose. Many pharmacies carry naloxone. Naloxone is available without a prescription in all 50 states, including over the counter at pharmacies. It is also possible to get naloxone from community-based distribution programs, local public health groups, or local health departments, free of charge.

Nalmefene is another overdose reversal medicine. 

Drug Test Strips

You cannot tell if another drug or pill contains fentanyl by looking at, tasting, or smelling it. Fentanyl test strips can help detect whether fentanyl is present in a drug or pill. These are small strips of paper that can check for fentanyl in different kinds of drugs and pills. Fentanyl test strips are legal to carry in most states and may be available through state and local health departments, syringe services programs, or drug stores and online retailers.

HA negative test result does not guarantee that a drug is fentanyl-free. Even if a drug contains fentanyl, the small sample you are testing may not have fentanyl in it, and the strips may not detect other similar drugs that could have been mixed in.

Xylazine test strips are also available, but a negative result does not guarantee that a drug is free of xylazine or other harmful substances.

Treatment for Opioid Use Disorder

Effective treatment for opioid use disorder includes medications, with behavioral therapies and other supports playing an important role for many people

Medicines

Medicines are the standard of care for opioid use disorder. Medicines approved by the U.S. Food and Drug Administration include methadone, buprenorphine, and naltrexone. Research has shown that these medicines help reduce opioid use and support recovery. Methadone and buprenorphine also reduce the risk of overdose and death. They help people remain in treatment and and support recovery.

Although medicines are effective, few with opioid use disorder receive them. People who live in rural or small suburban communities or who lack reliable transportation may not have an opioid treatment program nearby. Some people may have a hard time filling buprenorphine prescriptions because many pharmacies do not carry or dispense it. Stigma associated with substance use disorder treatment may also limit access to these medicines. People from racial and ethnic minoritized groups may face more barriers to medicine treatment for opioid use disorder than White individuals. Telehealth appointments may help people access medicines for opioid use disorder.

Behavioral Therapies

Behavioral therapies can be used along with medicines for opioid use disorder. Various types of behavioral therapy may help people stay in treatment and can address other needs, such as coexisting mental health problems.

Treatment During Pregnancy

Medicines for opioid use disorder are safe and effective for pregnant women. Methadone and buprenorphine are the standard of care to treat opioid use disorder during pregnancy. Treatment helps prevent opioid withdrawal symptoms and reduces the risk of returning to opioid use.

Breastfeeding is safe for people taking medicines for opioid use disorder and their infants. Breast milk contains only minimal amounts of the medicines for opioid use disorder that a person may be taking.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on opioids.

Find Treatment

• Find treatment for substance use disorders at FindTreatment.gov or call 1-800-662-HELP (4357).
• Learn more about treatment options for substance use disorder (SAMHSA)

Community Support

• HHS.GOV/OPIOIDS is a website from the U.S. Department of Health and Human Services that provides information about the national opioid crisis as well as help and resources.
• SAMHSA Opioid Overdose Prevention Toolkit has steps for responding to an opioid overdose.

Note: This resource list is for informational purposes only. It is not comprehensive, and an organization’s inclusion does not constitute an endorsement by NIH. 

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

NIH is funding research with the goal of finding scientific solutions to help end the opioid and overdose crisis. Studies seek to understand how opioids affect the brain and body and influence behavior. Researchers are also looking for better ways to prevent and treat opioid misuse, opioid use disorder, and overdose; reduce associated harms; and help people recover.

The NIH HEAL (Helping to End Addiction Long-term®) Initiative aims to develop new scientific solutions to the overdose epidemic, including opioid and stimulant use disorders, and the crisis of chronic pain.

NIH-funded studies have shown that allowing more take-home doses of methadone is safe and may help people stay in treatment, have better outcomes, and make more positive life changes. NIH-supported research also suggests that a faster treatment approach that reduces the waiting time to start naltrexone can be effective.

NIH is also supporting research for stronger formulations of naloxone for use with potent opioids like fentanyl. Research indicates that clinicians prescribing naloxone along with prescription opioids may reduce the risk of opioid-related emergency room visits and prescription opioid-involved overdose deaths.

Recent research shows that patients who fill an opioid prescription after a dental procedure have a higher overdose risk compared to patients who don’t receive opioids. An NIH-supported clinical trial found that an AI tool was as effective as healthcare providers in generating referrals to addiction specialists for opioid use disorder screening.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.