The Basics of Naltrexone for Opioid Addiction

This guide covers basic information on how naltrexone is used to treat opioid addiction, including how it works, how it’s administered, and how often it’s used. Details will also be provided on the cost of treatment, potential side effects, and other considerations of using naltrexone for opioid addiction.

Naltrexone blocks opioids from binding to the receptors in the brain, preventing the intense euphoric effects opioid abusers desire. It’s believed that the absence of this desired effect will decrease a person’s craving for opioids and help break the addiction, especially if the same result occurs repeatedly. Naltrexone has been used for numerous years to reverse opioid overdose, but it’s also been approved to treat opioid addiction with some success.

Generic Treatment Name Naltrexone is the generic name of brand-name medications ReVia, Depade, and Vivitrol, among others, used to treat opioid addiction.
Scientific Name Synthetic opioid antagonist
Introduced 1984 – pill formula

2010 – injectable extended-release formula

Conditions Commonly Treated Opioid dependence and addiction, alcohol abuse, reversal of opioid overdose
Availability Can be prescribed by any health care provider who is licensed to prescribe medications
How Administered Orally or monthly injections
Common Side Effects Nausea, vomiting, diarrhea, decreased appetite, headache, dizziness, nervousness, insomnia, muscle cramps, joint or muscle pain, anxiety, depression, elevated liver enzymes, vulnerability to opioid overdose
When Medical Treatment Required Liver disease, worsening skin reactions, allergic pneumonia, bacterial infections or necrosis at the injection site, or severe depression
Withdrawal Symptoms None

Background of Treatment

Naltrexone was initially approved in 1984 for the treatment of opioid dependence by the U.S. Food and Drug Administration (FDA). It was originally available as a 50 mg tablet that blocked the effects of opioids for 24 to 36 hours. A single pill was administered daily, or two pills were taken every other day, with no serious adverse events common when taking recommended doses. Tolerance build-up doesn’t occur, so there’s no addictive potential. However, the need to take doses so regularly made noncompliance a common occurrence. To help counter this problem, injectable extended-release naltrexone was created, which was approved by the FDA in 2010. This form of medication only needs to be administered once a month. However, neither pill nor injection forms of naltrexone can be used until after the person completes medically supervised withdrawal from opioid dependence.

How Much Is Naltrexone for Opioid Addiction Used

According to the National Survey of Substance Abuse Treatment Services, facilities with and without opioid treatment programs have steadily increased their use of injectable extended-release naltrexone following its approval in 2010. In the 2011 National Survey of Substance Abuse Treatment (NSSAT), 11% or 125 facilities with opioid treatment programs and 8% or 968 facilities without opioid treatment programs reported they provided injectable extended-release naltrexone. These numbers jumped to 23% and 16%, respectively, in 2015.

In 2013, the NSSAT collected counts of individual clients using injectable extended-release naltrexone and discovered that 359 clients in facilities with opioid treatment programs and 3,422 clients in facilities without these programs received the injections that year. By 2015, these numbers jumped to 712 clients in facilities with opioid treatment programs and 6,323 clients in facilities without these programs. However, these numbers may actually be higher because they only included clients receiving services through a treatment facility and not those who may have received treatment through independent medical professionals.

What Naltrexone Is Used for and How It Works

Naltrexone has previously been used to reverse opioid overdose and, more recently, to prevent relapse to opioid use following withdrawal. The FDA has also approved naltrexone for the treatment of alcohol use disorder, so it’s particularly useful to those suffering from both opioid use disorder and alcohol use disorder. Naltrexone should only be used as part of a comprehensive opioid recovery program that may include counseling, behavioral therapies, support groups, continuing care, and other treatment methods recommended by your health care or addiction treatment provider.

Naltrexone works by blocking the calming and euphoric effects of opioid-based drugs, including prescription pain relievers and heroin. Unlike methadone and buprenorphine, which may help ease withdrawal symptoms by taking the place of opioids, naltrexone binds and blocks opioid receptors to help reduce opioid cravings. Also, unlike the other two medications, it can’t be used during withdrawal. You must undergo detox before beginning naltrexone treatment for opioid addiction. While taking naltrexone, you shouldn’t use any opioids, drink alcohol, or take sedatives or tranquilizers. Research shows taking naltrexone can help prevent a person from relapsing to opioid use.

How Naltrexone Is Administered

Naltrexone can be prescribed by any health care provider licensed to prescribe medications. Before beginning naltrexone treatment, medically supervised withdrawal is necessary, or withdrawal symptoms may be more severe. For short-acting opioids, this requires 7 to 10 days of detox or 10 to 14 days for long-acting opioids. It’s inadvisable for women who are pregnant to take naltrexone.

Oral naltrexone is often administered daily, but it may be taken every other day or sometimes three times per week. Peak concentrations occur within one to two hours of taking a dose. The injectable extended-release form of naltrexone is administered once per month intramuscularly. The injected version is known by the brand name Vivitrol and reaches a short-lived peak concentration two hours after injection with another two to three days following injection. After that, concentrations gradually fall between days 14 and 30.

Cost, Side Effects, and Other Considerations

The cost of opioid treatment varies based on numerous factors, but the cost of monthly injections of naltrexone is higher than others. According to 2016 estimates from the U.S. Department of Defense, the cost of injectable naltrexone was $1,176.50 monthly, which includes the medication, administration fees, and other related services. Compared to daily methadone treatments at $6,552 annually and buprenorphine treatments at $5,980 annually, naltrexone was $14,112 annually.

Naltrexone tends to have a relatively small number of side effects, but taking this medication may cause minor side effects that usually disappear once your body becomes accustomed to taking it. Both the pill and injection may cause anxiety, insomnia, nausea, vomiting, diarrhea, headache, dizziness, muscle cramps, joint and muscle pain, elevated liver enzymes, liver damage, depression, and vulnerability to opioid overdose. Injection naltrexone may also cause pain and swelling at the site of injection and intramuscularly, common cold symptoms, and toothache. However, unlike other medications used for opioid addiction, naltrexone isn’t misused and doesn’t cause slowed breathing, drowsiness, or withdrawal symptoms when you quit.

Other considerations before taking naltrexone include being vulnerable to death by overdose, which could occur if you use high doses of opioids trying to override the block created by the medication. You could also be at a higher risk of overdose if you miss a dose or stop treatment. Occasionally, naltrexone use has been associated with feeling unhappy or uneasy, which may be caused by underlying depression related to opioid use disorder and not the medication.

Liver disease, including hepatitis, can occur, so seek medical evaluation if you notice any yellowing of the eyes or skin. Naltrexone may also cause allergic pneumonia or hypersensitivity that may cause mild skin irritations or severe allergic reactions. Mild injection site reactions may include itching, reddening of the skin, tenderness, and bruising; severe reactions may include abscess, bleeding beneath the skin, bacterial infection, and necrosis that may require surgery that could cause significant scarring.

How to Get Help & Additional Resources

Learn more about treatment programs for opioids, alcohol, and other drugs with this guide to Alcohol and Drug Detox Centers.

  • MedlinePlus explains the meaning of Opioid Misuse and Addiction Treatment, including treatment options, such as medicines and counseling used to treat opioid misuse and addiction.
  • The Substance Abuse and Mental Health Services Administration offers a brief guide on the Clinical Use of Extended-Release Injectable Naltrexone in the Treatment of Opioid Use Disorder, including assessing the need for treatment, initiating medication-assisted treatment, adjusting the treatment plan, and deciding if and when to end medication-assisted treatment.
  • The National Institute of Drug Abuse offers detailed information about the Medications to Treat Opioid Use Disorder, including effectiveness, cost, and accessibility of naltrexone.

Disclaimer: The information contained in this guide is for informational purposes and only intended to educate the public on how this treatment is used. It is not recommending a specific treatment or giving medical advice. Always consult with your doctor or other qualified medical and addiction professionals before beginning any type of treatment.