Back to
Updated on July 21, 2025
Opioids are a category of drug that bind to receptors (called opioid receptors) found throughout the brain and spinal cord. A receptor is a protein found on the surface of a cell, in this case neurons or nerve cells found in the brain and spinal cord.
When an opioid binds to an opioid receptor, that receptor activates, triggering a series of events that block pain signals and cause a release of large amounts of endorphins, neurochemicals associated with feelings of pleasure and euphoria. Opioids also cause a person to feel drowsy.
Opioid use disorder (OUD) is a medical condition characterized by the chronic use of opioid drugs. This includes the use of prescription opioid medications as well as illegal opioid drugs.
People with OUD experience an intense physical and psychological need to take opioids. Over time, a person with OUD will develop a tolerance to opioids that leads to an increase in the quantity of opioids they take, and they will experience withdrawal symptoms if they stop taking opioids. The need and use of opioids leads to significant distress and negatively impacts many aspects of a person’s life, including relationships, finances, employment, and legal issues. Serious complications can occur, and opioid overdose is a leading cause of death in the United States.
There are effective treatments for OUD. While treatment will vary from person to person, a treatment plan will typically include a combination of medications, therapy, and support.
Medications for opioid use disorder (MOUD)
Sometimes referred to as MOUD, medications for opioid use disorder can fit into a treatment plan for OUD in several ways:
Medications to treat withdrawal
Withdrawal occurs when a person with opioid dependence stops taking opioids or reduces the amount of opioids they are taking. Withdrawal can also occur when starting or transitioning to a medication called buprenorphine (which is used to treat withdrawal as well as maintenance therapy, and is discussed below). A variety of medications may be prescribed to reduce or ease symptoms of withdrawal, which can include anxiety, sleep problems, muscle pain, pounding heartbeat, diarrhea, nausea, and vomiting.
Maintenance therapy
Maintenance therapy refers to MOUD that is taken long-term or continuously and refers to three medications—methadone, buprenorphine, and naltrexone.
Methadone and buprenorphine act on the same receptors as the opioid drugs commonly used by people with OUD. Though both are classified as opioids, therapeutic doses of these drugs produce a different response in the brain, without the intense feelings of pleasure or intoxication. In addition to maintenance therapy, these drugs can also be used to treat withdrawal.
A key difference between methadone and buprenorphine is where these medications can be accessed:
- In the U.S. methadone is only available through opioid treatment programs.
- Buprenorphine can be prescribed by a healthcare provider with a standard license to prescribe pharmaceuticals, such as a primary care provider.
Both drugs also differ in the formulations available:
- Methadone is available as pills, dissolvable tablets, liquid concentrates, and powder that is mixed with liquid. Doses must be taken daily.
- Buprenorphine is available as tablets or films that can be dissolved under the tongue or inside the cheek that are taken daily.
- Buprenorphine is also available as an extended-release injection that can be administered by a healthcare provider (either weekly or monthly depending on the dose and specific drug).
- There is also a MOUD that is a combination of buprenorphine and another drug called naloxone.
Naltrexone is another opioid agonist that can be taken as a daily oral medication or a long-acting injection given monthly. It does not treat withdrawal, and a person must complete detoxification 7 to 10 days prior to starting treatment with this medication.
Emergency treatment
People with OUD are also advised to carry a medication called naloxone as an emergency treatment for opioid overdose. It can quickly restore normal breathing if a person has slowed or stopped breathing from an opioid overdose. This medication is available as an injection or a nasal spray.
It’s important to remember that there is no best treatment for OUD, only the treatment that works best for an individual person. Your best source of information will be a healthcare provider.
