Naltrexone Effects

Table of Contents

Naltrexone is a drug used as part of medication-assisted treatment, or MAT, for those recovering from alcoholism or addiction to opioids (e.g., heroin, painkillers).

Naltrexone is an effective drug in addiction treatment, as its primary effect is blocking the euphoria associated with opioids and alcohol to discourage people from abusing these drugs for their pleasurable effects. Side effects of this drug may include nausea, vomiting, anxiety, and changes in mood.

Naltrexone is a prescription medication used to treat addiction to alcohol and opioids like heroin, morphine, oxycodone, and hydrocodone.1 Naltrexone is what’s known as an opioid antagonist and works by blocking the pleasurable effects of opioids and alcohol.3

Taking naltrexone can help reduce cravings for alcohol and opioids and will prevent a person from fully experiencing the pleasurable “high” should a relapse occur.2 It is commonly taken as a tablet; however, a once-monthly injection (Vivitrol) is also available.2

How Is Naltrexone Used?

Medication-assisted treatment, or MAT, is a type of treatment for substance use disorders that combines prescription medications with counseling and behavioral therapy.3 Medications used in MAT are approved by the Food and Drug Administration (FDA) for the treatment of addiction. When used in conjunction with therapy, these medications can improve abstinence rates and reduce the chances of a relapse.

Will Naltrexone Cure Addiction?

Addiction is a complex illness that many struggle with their whole lives. Many addicted people require a comprehensive treatment approach that consists of prescription medications alongside counseling and therapy to help them maintain long-term abstinence from drugs and alcohol.

Naltrexone is one of several medications that can help opioid and alcohol addicts manage cravings and prevent relapse. It is most helpful when it is 1) combined with counseling, education, and support groups and 2) monitored closely by a trained medical professional.1 Naltrexone does not cure addiction but, when used as an adjunct to other approaches, it can help improve the chances of abstinence and long-term recovery.

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), the various medications used in MAT work by:3

  • Blocking the intoxicating effects of alcohol and opioids.
  • Restoring brain chemistry to normal levels.
  • Restoring the body’s normal functioning in absence of the abused drug.
  • Reducing cravings.

MAT has been shown to:3

The goal of naltrexone as part of MAT is to deter people in early recovery from relapsing on their drug of choice. Because naltrexone blocks the pleasurable effects associated with alcohol and opioids, it is an effective tool in reducing the compulsive drive of addicts in recovery to return to those drugs.

It is administered as either a pill or an extended-release, injectable suspension:

  • The pill form of naltrexone may be prescribed for use at home or provided in a clinic. It may be prescribed as a 50 mg dose once daily, but when provided at a clinic or treatment center the regimen may vary somewhat.1,2
  • Vivitrol, an intramuscular injectable form of naltrexone, is given at a dose of 380 mg once per month. To help prevent an abruptly precipitated withdrawal, a person must abstain from opioids for 7-10 days before starting treatment with naltrexone.2

Medication like naltrexone should be offered in conjunction with behavioral therapies like cognitive behavioral therapy and contingency management.

Participation in peer-led recovery support groups like Alcoholics Anonymous and Narcotics Anonymous can be hepful. The ongoing support from similar peers can be key to long-term sobriety.

Who Should Take It?

Man looking down wondering if he should take Naltrexone for addiction

While naltrexone is recommended for the treatment of alcohol and opioid dependencies, it won’t be right for every recovering individual. It is not recommended for anyone experiencing active liver failure or hepatitis.4 Naltrexone may also not be appropriate for people who are:4

  • Currently using illicit opioids.
  • Experiencing active opioid withdrawal.
  • Participating in methadone treatment.
  • Pregnant or breastfeeding.
  • Those with renal impairment.

Some prescription medications may negatively interact with naltrexone and may diminish its effects or cause additional side effects:3,4

  • Combining it with benzodiazepines like Valium and Xanax can have adverse effects and may even cause fatal reactions.
  • Taking high doses of naltrexone (200-250 mg per day) with nonsteroidal anti-inflammatory drugs (NSAIDs), like aspirin and ibuprofen, can harm the liver.

The Concerns of Drinking on Naltrexone or Mixing with Sedatives or Tranquilizers

It is important to discuss all medications you are taking with your doctor to prevent dangerous drug interactions. Naltrexone users should avoid drinking alcohol and using sedatives, tranquilizers, opioids, and all illicit drugs.2

Using opioids while taking naltrexone can be lethal. Here’s why: naltrexone blocks the euphoric effects of opioids, so when you take them while on naltrexone you won’t feel these effects (or you’ll feel them to a lesser degree). If you increase the dose to recreate the high you’re accustomed to, you can overdose and succumb to serious injury, coma, or death.

Naltrexone users are also likely to have lowered their tolerance to opioids during their course of treatment, which can increase the risk of an overdose should they take them again after stopping naltrexone.1

Medication-assisted treatments like naltrexone can have serious side effects so it is essential to speak openly with your medical provider about whether it’s the right option for you. Be honest about your medical and mental health history. This can include any:

  • Pre-existing medical conditions.
  • Current medications.
  • Past and current mental health issues.
  • Complete history of substance use.

Side Effects and Risks

Medication-assisted treatments can have short- and long-term side effects. Short-term side effects of naltrexone may include:1

In rare cases, naltrexone users may have serious side effects such as:1

  • Severe vomiting or diarrhea.
  • Blurry vision.
  • Extreme confusion.
  • Hallucinations.

  • Nausea.
  • Vomiting.
  • Diarrhea.
  • Constipation.
  • Poor appetite.
  • Headache.
  • Dizziness.
  • Anxiety.
  • Agitation.
  • Depressed mood.
  • Changes in sleep.
  • Changing energy levels.
  • Muscle or joint pain.

For some users, naltrexone may cause:1,2

  • Liver damage. The risk of liver damage may increase with higher doses of naltrexone and for people with a history of hepatitis or liver disease.
  • Allergic pneumonia.
  • Infections or skin reactions. Users who take Vivitrol (the injectable form of the drug) may have reactions at the injection site that require medical evaluation.

Alternatives to Naltrexone for Opioid and Alcohol Addiction

Numerous treatment settings utilize medication-assisted treatment as part of their therapeutic approach.

Naltrexone is only one drug used in MAT. Other prescription drugs have also been shown to be effective in treating alcohol and opioid addiction.

Additional medications for opioid addiction include:3,5

  • Methadone—This full opioid agonist can lessen or prevent withdrawal symptoms and help opioid users manage cravings.6 It works by activating the opioid receptors in the brain but to a lesser extent than drugs like heroin and oxycodone. Methadone is only available in specially licensed clinics.
  • Buprenorphine—This partial opioid agonist can help manage acute withdrawal and decrease cravings for opioids.7 Suboxone combines buprenorphine with naloxone, an opioid antagonist that may cause a withdrawal reaction if the user attempts to abuse the drug by injecting it. Suboxone may be prescribed by physicians with a special certification.

Additional medications for alcohol addiction include:3,5

  • Acamprosate (Campral)—This drug can help reduce cravings for alcohol. The medication is available as a tablet that is taken 3 times a day.8
  • Disulfiram (Antabuse)—This once-a-day tablet causes unpleasant side effects if a person drinks even a small amount of alcohol. These effects may include nausea, vomiting, chest pains, headache, and difficulty breathing.9

Numerous treatment settings utilize medication-assisted treatment as part of their therapeutic approach. These include both inpatient and outpatient programs. If you’re interested in taking naltrexone, speak to a doctor or addiction treatment professional about whether the medication would be a good fit for you.


  1. U.S. National Library of Medicine. (2009). MedlinePlus, Naltrexone.
  2. Substance Abuse and Mental Health Services Administration. (2016). Naltrexone.
  3. Substance Abuse and Mental Health Services Administration. (2015). Medication and counseling treatment.
  4. Center for Substance Abuse Treatment. (2009). Incorporating alcohol pharmacotherapies into medical practice. HHS Publication No. (SMA) 09-4380. Rockville, MD: Substance Abuse and Mental Health Services Administration.
  5. National Institute on Drug Abuse. (2014). Principles of adolescent substance use disorder treatment: A research-based guide.
  6. U.S. National Library of Medicine. (2017). MedlinePlus, Methadone.
  7. U.S. National Library of Medicine. (2017). MedlinePlus, Buprenorphine sublingual and buccal (opioid dependence).
  8. U.S. National Library of Medicine. (2016). MedlinePlus, Acamprosate.
  9. U.S. National Library of Medicine. (2012). MedlinePlus, Disulfiram.
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    Emily Guarnotta holds a doctorate degree in Clinical Psychology from the California School of Professional Psychology. She has a passion for working with clients struggling with substance abuse and mental health issues. Her treatment approach includes providing evidence-based practices in a supportive and non-confrontational manner.

    Emily's experience also includes working with college students, clients with severe mental illness, and delivering crisis intervention services.