MAT Facts is a special CleanSlate blog series that answers questions, corrects misunderstandings, and combats stigma around addiction and medication-assisted treatment (MAT).

Amongst the three FDA-approved addiction medications, naltrexone – better known by its brand names, Vivitrol or Revia – is the least utilized.

While Suboxone (buprenorphine) and methadone are more popular, naltrexone helps people suffering from opioid use disorder (OUD) and alcohol use disorder (AUD) through different properties.

One of the unique qualities of naltrexone is that it can be administered once per month as an extended-release injectable (Vivitrol). This is one reason that Vivitrol is often given when a person is released from the prison system or a detox.  It reduces the risk of overdose for a full month to give the person time to get into treatment. 

Unlike buprenorphine and methadone, naltrexone is an opioid antagonist, which means that it blocks opioid receptors and the effects that opioids like heroin, oxycodone, and morphine have on the brain. Naltrexone prevents the high associated with taking an opioid. This means if a person uses an opioid while on naltrexone, it’s unlikely to turn into a full relapse because the high is blocked. 

Related blog: MAT Facts: What is Medication-Assisted Treatment?

Because it is not itself an opioid, naltrexone does not pose any risks for abuse or diversion. But patients who relapse can suffer life-threatening consequences and overdose if they keep using more and more opioids in an effort to get the high that naltrexone blocks. The high is blocked but not the effects that opioids have on stopping breathing and causing overdose. People who receive naltrexone but don’t seek treatment to continue care are at particularly high risk for overdose, because they are no longer tolerant to opioids.  

The challenge of this medication is that it requires patients to not have any opioids in their system for a minimum of 7-10 days – prior to taking the first dose. That’s another reason why Vivitrol is often used following detox or incarceration because that person has not recently used an opioid.  Patients taking methadone or buprenorphine who want to switch to Vivitrol have to undergo a wean off these medications before they can start Vivitrol. It’s important to wean off with a doctor’s supervision because sudden opioid withdrawal can be severe and may require hospitalization.

Further, naltrexone does not treat withdrawal and is not recommended for pregnant patients.

Related blog: MAT Facts: How Does Buprenorphine Work?

The daily oral version of naltrexone, Revia, can be prescribed by any licensed prescriber and filled at a pharmacy. The monthly injectable versions (XR-NTX or Vivitrol) are typically specialty pharmacy products.

Side Effects of Naltrexone

People who take naltrexone may experience side effects, which can include:

  • Upset stomach or vomiting
  • Diarrhea
  • Headache
  • Nervousness
  • Sleep problems/tiredness
  • Joint or muscle pain

Patients should continue taking naltrexone even if they experience side effects, but they should contact their doctor to possibly adjust the dosage.

SAMHSA advises patients to immediately seek a healthcare provider if they experience the following:

  • Liver injury: Naltrexone may cause liver injury. Seek evaluation if have symptoms and or signs of liver disease.
  • Injection site reactions: This may occur from the injectable naltrexone. Seek evaluation for worsening skin reactions.
  • Allergic pneumonia: It may cause an allergic pneumonia. Seek evaluation for signs and symptoms of pneumonia.

Vivitrol advises that it is not right for everyone. There are significant risks from VIVITROL treatment, the company states, including risk of opioid overdose, severe reaction at the injection site, and sudden opioid withdrawal.

As with the other addiction medications, naltrexone is meant to be used as part of a comprehensive MAT program which tailors treatment to the needs of each individual. This can include counseling and other wraparound services. If you are interested in assistance, take a look at our articles about Wilkes-Barre Medicaid Drug Rehab and Outpatient Rehab in Mechanicsville for more.

CleanSlate treats patients suffering from opioid or alcohol addiction with medications and a continuum of care to support each individual’s journey to recovery. If you or someone you love needs help, contact us at 833-505-HOPE, or visit our website at to find the addiction treatment center nearest you.

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Tracey Cohen M.D.

Dr. Cohen, Chief Clinical Officer of CleanSlate, is responsible for the clinical and quality oversight of CleanSlate’s services as well as continuous improvement and development of CleanSlate’s model of care. A part-time clinical provider at CleanSlate since 2010, Dr. Cohen joined the CleanSlate leadership team full-time in the summer of 2018, bringing over seventeen years’ experience of leadership in direct care, managed care, and public policy. Board certified in Addiction Medicine and Family Medicine, Dr. Cohen is widely recognized as a leader in substance use disorder care, health care integration, primary care, and chronic pain management. In her previous roles as Medical Director of Neighborhood Health Plan of Rhode Island and as Medical Director of Behavioral Health and Quality at BCBS Rhode Island, Dr. Cohen led initiatives that expanded access to addiction treatment across the state and served as regional and national models. Dr. Cohen earned a Bachelor of Arts degree in psychology from Barnard College and a Doctorate in Medicine from University of Pennsylvania School of Medicine where she was one of the six inaugural Twenty-First Century Scholars.