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What is Naltrexone?

Naltrexone is a medicine approved by the Food and Drug Administration (FDA.) It is used in medication-assisted treatment (MAT) to treat opioid and alcohol use disorders. Patients can take naltrexone in a pill form or as an injectable.

The pill form of naltrexone is taken at 50 mg once per day. The injectable extended-release type of the drug is taken at 380 mg intramuscular once a month. 

Any healthcare provider or doctor who is licensed to prescribe medications can prescribe naltrexone to patients.

To lessen the risk of precipitated withdrawal, patients should abstain from illicit opioids and opioid medication for a minimum of seven to ten days before starting naltrexone. If swapping methadone for naltrexone, the patient must be completely withdrawn from the opioids.


Brand Names for Naltrexone

Naltrexone is available under the following brand names:

  • ReVia
  • Vivitrol
  • Depade

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How is Naltrexone Used to Treat Alcohol Use Disorder (AUD)?

When beginning naltrexone for an alcohol use disorder (AUD), patients cannot be using alcohol or other drugs. To prevent strong side effects like nausea and vomiting, health professionals usually wait until after the alcohol detoxification process before giving patients naltrexone.

Naltrexone connects to the endorphin receptors in the body and blocks the feelings and effects of alcohol. The medication reduces alcohol dependence cravings and the amount of alcohol consumed. Once a patient stops drinking, naltrexone helps them maintain abstinence from alcohol.

Naltrexone MAT treatment for alcohol dependence lasts for around three to four months. Practitioners should continue to monitor patients who stop using naltrexone.

How is Naltrexone Used to Treat Opioid Use Disorder (OUD)?

Extended-release injectable naltrexone is approved for patients with opioid use disorder. Any healthcare provider or doctor who is licensed to prescribe the medication can prescribe it. Special training is not necessary. 

Medically managed detoxification from opioids must be completed at least seven to ten days before injectable naltrexone is administered. A professionally managed detoxification process helps patients manage their opioid withdrawal symptoms.

Naltrexone reduces reactivity to drug-conditioned cues and lessens cravings. Patients treated with extended-release injectable naltrexone for opioid addiction may have reduced tolerance to opioids. They may also be unaware of their potential sensitivity to the same, or lower, doses of opioids they were previously used to.

Extended-release naltrexone should be a segment of a comprehensive treatment program that includes psychosocial help and support groups.

How Does the Medication Work?

Naltrexone blocks the sedative and euphoric effects of opioids like heroin, morphine, and codeine. It works differently in the body compared to buprenorphine and methadone, which trigger opioid receptors in the body that reduce cravings.

The medication binds and blocks opioid receptors and reduces opioid use cravings. If an individual relapses and uses the problem drug, naltrexone stops the feeling of becoming high.

People taking naltrexone should not use any other opioids, illicit drugs, sedatives, or tranquilizers. They should also avoid drinking alcohol.

If patients treated with naltrexone relapse after some time of abstinence, it is possible that the dosage of naltrexone previously used may have life-threatening results, including respiratory arrest and circulatory collapse.

Like all medications used in medication-assisted treatment (MAT), naltrexone should be part of a comprehensive treatment program that includes counseling and participation in social support programs.


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Potential Side Effects of Naltrexone

Patients taking naltrexone may experience some adverse effects, but they should not stop taking the medication. Instead, they should speak with their health care provider to change the dose or swap the medication.

Some common side effects include:

  • Upset stomach or vomiting 
  • Diarrhea 
  • Headache
  • Nervousness 
  • Sleep issues/tiredness 
  • Muscle or joint pain

Are There Any Risks Associated with Naltrexone?

Naltrexone blocks the euphoric feeling you experience from opioid drugs, including heroin. As naltrexone may make you more sensitive to smaller doses of opioids you have previously used, you should not take heroin or other narcotic drugs to overcome what the medication is doing. You may experience an opioid overdose and develop serious problems.

Another risk is that naltrexone may cause severe problems with your liver function, such as liver disease. Call your doctor immediately if you start experiencing dark urine, pain in the upper stomach, or yellowing of the skin or eyes while you are taking this medicine.

Naltrexone may also increase thoughts of suicide. Tell your doctor if you start to feel more depressed. You should also speak with your doctor if you have ideas about hurting yourself.

Report any unusual behaviors or thoughts that concern you, especially if they are new or worsen quickly.

Make sure to speak with your doctor if you experience any of the following:

  • Sleeping a lot more or a lot less than usual
  • Feeling hopeless or helpless
  • Difficulties sleeping
  • Feeling upset easily
  • Experiencing a significant increase in energy
  • Acting recklessly
  • Sudden or strong feelings, such as feeling nervous, angry, violent, restless, or scared

What Happens If You Miss a Dose of Naltrexone?

If you miss a dose of naltrexone, take it as soon as possible. However, if it is time for your next dose, go back to your regular dosing schedule and skip the missed dose. Do not double dose.

Benefits of Medication-Assisted Treatment (MAT) for Alcohol & Opioid Addiction

In 2018, an estimated two million people had an opioid use disorder. This figure includes prescription pain medication containing opiates and heroin. Clinical trials have proven MAT to be effective and to lessen the need for inpatient detox services.

MAT delivers a more comprehensive, individually tailored addiction treatment program of medication and behavioral therapy that considers the needs of most patients.

The goal of MAT is complete recovery, including the chance to live a happy, healthy life free of drug abuse and alcohol dependence.

This treatment approach has demonstrated to:

  • Improve patient survival 
  • Heighten retention in treatment 
  • Reduce illicit opiate drug use and other criminal activity among people with substance use disorders 
  • Increase patients’ opportunities and ability to gain and maintain employment 
  • Improve birth outcomes among women suffering from substance use disorders that are pregnant 

MAT medications and therapies can also reduce a person’s risk of contracting HIV or hepatitis C by lessening the potential for relapse.

Other Therapies Used With MAT

MAT patients receiving treatment for an opioid use addiction must accept counseling. This may include various forms of behavioral therapy. These services are required along with medical, educational, vocational, and other assessment and treatment services.

Regardless of what setting MAT is delivered in, treatment is more effective when counseling and other behavioral health therapies are included to give patients a whole-person approach.

Many people with a substance use disorder also have a mental illness. This is known as a co-occurring disorder. Patients with a co-occurring mental health disorder typically receive treatment for it as well as their substance use disorder (SUD).

In addition, patients may have other health-related conditions like hepatitis, HIV, and AIDs that require treatment.

What to Discuss With Your Health Care Provider Before Taking Naltrexone

Before naltrexone treatment, patients should speak with their healthcare provider for medical advice about all the current medications they are taking and any adjustments in medications while being treated. 

Patients should also speak with their healthcare provider if they are pregnant or breastfeeding.

How to Find Treatment 

MAT medications are dispensed, administered, and prescribed in various settings. These include SAMHSA-accredited and certified opioid treatment programs (OTP) or certified practitioners, depending on the medication used.

There is also an Opioid Treatment Program Directory to help people find treatment programs accredited to treat opioid use disorders like prescription medications and heroin by state.

Updated on November 16, 2021
6 sources cited
  1. Naltrexone, Substance Abuse and Mental Health Services (SAMHSA), September 2020,
  2. Naltrexone (Oral Route), Mayo Clinic, February 2021,
  3. Medication-Assisted Treatment (MAT), Substance Abuse and Mental Health Services (SAMHSA), April 2021,
  4. Find Medication-Assisted Treatment (MAT), Substance Abuse and Mental Health Services (SAMHSA), August 2020,
  5. Anton, Raymond F. “Naltrexone for the management of alcohol dependence.” The New England journal of medicine vol. 359,7 : 715-21,
  6. Farrell, M, and J Strang. “Compressed opiate withdrawal syndrome and naltrexone.” Journal of psychopharmacology (Oxford, England) vol. 9,4 : 383-5,

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