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Naltrexone is one of three prescription medications approved by the US Food and Drug Administration (FDA) to treat both opioid use disorder and alcohol use disorder. Naltrexone treatment is generally most successful when paired with behavioral therapy and some form of substance abuse treatment program.

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Pharmacology of Naltrexone

The use of naltrexone has a high success rate for recovering addicts. Naltrexone can be used to promote abstinence from opioids or alcohol by decreasing cravings in the user.

Naltrexone is an opioid antagonist, which means it binds to the opioid receptors of the brain to block the effects of any other opioids. Blocking opioid effects help recovering addicts remain sober and avoid returning to opioid use.

Research is still being conducted about how naltrexone effectively blocks the effects of alcohol in the brain, but current research suggests that naltrexone blocks certain endorphins that alcohol can create. Therefore, by eliminating any positive impact of alcohol, naltrexone helps former alcohol users to abstain from drinking.

Brand Names for Naltrexone

Naltrexone comes in various forms and is known by different brand names. Naltrexone can be taken as a tablet daily, as a monthly shot, or inserted as a tiny device that lasts up to six months. The insert is the only form of naltrexone that is only available during hospitalization or other inpatient care.

The most common naltrexone brand names are:

  • Vivitrol®
  • ReVia®
  • Depade®
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How Naltrexone is Used

Naltrexone can be used alone or in conjunction with another medication as part of medication-assisted treatment for certain substance use disorders, particularly opioid use disorder and alcohol use disorder.

If you are struggling with alcohol use disorder or opiate addiction, your doctor or similar healthcare provider can prescribe naltrexone as part of your overall treatment plan.

Naltrexone comes in a few different forms:

  • Oral naltrexone comes in tablet form and can be self-administered at home. Tablets are currently the most common method of taking naltrexone.
  • Injectable naltrexone is an intramuscular shot that is provided every 4 weeks by a healthcare professional. Injection site reactions can include itching, redness, bruising, soreness, or swelling at the injection site. Speak with your doctor if any of these symptoms persist after two weeks.
  • Implant naltrexone is a small pellet-like device inserted under the skin to provide long-acting naltrexone effects for 3-6 months at a time. However, implants are currently only available during inpatient treatment.

Naltrexone Use Special Precautions & Warnings

There are a few important precautions to be aware of when taking naltrexone.

Patients using naltrexone will usually develop a lower tolerance to opioids. If a patient stops using naltrexone and returns to opioid use, even a lower dose of opioids can cause a life-threatening overdose.

Naltrexone use may be also contraindicated, or not recommended, for certain patients with other health conditions.

These naltrexone contraindications include:

  • Pregnant or breastfeeding
  • Severe hepatitis
  • Liver disease, liver failure
  • Hemophilia or other bleeding issues
  • Kidney disease

It is also important to let your doctor know if you are currently being treated for opioid use disorder or alcohol use disorder. If you are taking any other medications, including supplements, be sure to discuss that with your clinician as well.

Side Effects of Naltrexone

Naltrexone is a relatively safe medication when taken as directed, but may still have some side effects. The Substance Abuse and Mental Health Services Administration (SAMHSA) lists the following potential effects of naltrexone use.

Common naltrexone side effects include:

  • Decreased appetite
  • Increased tiredness
  • Headache
  • Dizziness
  • Nausea or vomiting
  • Muscle cramps
  • Painful joints
  • Toothache
  • Insomnia
  • Cold-like symptoms

Rare, but more serious side effects of naltrexone include:

  • Severe reactions at the injection site
  • Depression
  • Liver damage
  • Pneumonia
  • Allergic reactions

Medical Uses of Naltrexone

Naltrexone is prescribed as medication-assisted treatment for both opioid use disorder (OUD) and alcohol use disorder (AUD). It is usually prescribed after the individual has completed the detoxification process for alcohol or opioids.

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Naltrexone for Alcohol Use Disorder

Patients struggling with alcohol abuse can get treatment through inpatient or outpatient treatment programs. During treatment, patients with alcohol dependence may receive a prescription for naltrexone after the detox process.

Other medications used to treat alcohol use disorder include acamprosate and disulfiram.

Naltrexone works by blocking endorphins in the brain, making it useful in the long-term treatment of alcohol dependence. Users will not experience any euphoric effects from alcohol while on naltrexone which helps them remain sober.

Naltrexone treatment for alcohol use disorder lasts between 3 and 4 months. Patients will check in with their doctor during treatment and follow up after they have completed naltrexone.

Naltrexone for Opioid Use Disorder

Naltrexone can also be prescribed for treating opioid use disorder. Other medications used to treat opioid use disorder include buprenorphine and methadone.

Naltrexone works by blocking the effects of opioids in the brain so users don’t feel any euphoric effects. As a result, many opioid-dependent patients can choose to remain opioid-free during and after their treatment.

Individuals struggling with opioid dependence that take naltrexone will experience opioid withdrawal symptoms if they haven’t fully detoxed from their opioid drug use. Naltrexone is usually prescribed as a maintenance medication after the withdrawal process is complete.

It is important to note that naltrexone patients that have quit opioid use will have a lower tolerance to opioids. In the event of a relapse, even a lower dose of opioids than the person is used to can lead to a fatal opioid overdose.

Wondering If Naltrexone Can Help You or a Family Member?

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Kent S. Hoffman, D.O. is a founder of Addiction HelpReviewed by:Kent S. Hoffman, D.O.

Chief Medical Officer & Co-Founder

  • Fact-Checked
  • Editor

Kent S. Hoffman, D.O. has been an expert in addiction medicine for more than 15 years. In addition to managing a successful family medical practice, Dr. Hoffman is board certified in addiction medicine by the American Osteopathic Academy of Addiction Medicine (AOAAM). Dr. Hoffman has successfully treated hundreds of patients battling addiction. Dr. Hoffman is the Co-Founder and Chief Medical Officer of and ensures the website’s medical content and messaging quality.

Jessica Miller is the Content Manager of Addiction HelpWritten by:

Editorial Director

Jessica Miller is the Editorial Director of Addiction Help. Jessica graduated from the University of South Florida (USF) with an English degree and combines her writing expertise and passion for helping others to deliver reliable information to those impacted by addiction. Informed by her personal journey to recovery and support of loved ones in sobriety, Jessica's empathetic and authentic approach resonates deeply with the Addiction Help community.

  1. Medication-assisted treatment (MAT). SAMHSA. (n.d.). Retrieved March 30, 2022, from

  2. Naltrexone. SAMHSA. (n.d.). Retrieved March 31, 2022, from

  3. Office of the Assistant Secretary for Health (OASH). (2021, December 29). HHS expands access to treatment for opioid use disorder. Retrieved March 30, 2022, from

  4. Substance Abuse and Mental Health Services Administration. Medications for Opioid Use Disorder. Treatment Improvement Protocol (TIP) Series 63 Publication No. PEP21-02-01-002. Rockville, MD: Substance Abuse and Mental Health Services Administration, 2021. Retrieved March 31, 2022, from

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