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Is Naltrexone a Controlled Substance?

Is Naltrexone a Controlled Substance?

Naltrexone, marketed under the brand name Vivitrol, is not a controlled substance. It is not classified as a narcotic. Naltrexone is an opioid antagonist, not an opioid. It binds to opioid receptors and blocks the effects of opioids and narcotics.

Unlike opioids, Naltrexone does not have the potential for recreational abuse, and it does not lead to physical dependence or addiction.

Naltrexone is FDA-approved to treat alcohol use disorder and opioid use disorder. By blocking opioid receptors, it decreases alcohol and opioid-induced cravings and reduces the risk of relapse.

Naltrexone is also used off-label to treat chronic pain, fatigue, and inflammation. When combined with bupropion, Naltrexone is used for weight management.

How Is Naltrexone Regulated?

In the U.S., narcotics are regulated as Schedule I to IV controlled substances. All opioids are controlled substances in the U.S. They are regulated under the Federal Food, Drug, and Cosmetic Act (FD&C Act) and the Controlled Substances Act (CSA).

Depending on their abuse potential, opioids can be classified between Schedule I and IV. Schedule I and II drugs carry a higher abuse potential than Schedule IV. These medications are potentially dangerous or addictive. Only healthcare providers with a DEA license issued by the U.S. Drug Enforcement Administration (DEA) are permitted to dispense them.

Naltrexone is not a narcotic or controlled substance, so it is not classified under this system. However, Naltrexone has potential side effects and interactions, some of which can be serious. It is important to fully understand the risks and benefits of Naltrexone and other prescription medications before taking them. Naltrexone requires a prescription from a licensed healthcare provider.

What Does Naltrexone Treat?

Naltrexone is FDA-approved to treat alcohol use disorder (AUD) and opioid use disorder (OUD). It is used off-label to treat many conditions, including chronic pain and inflammation. Many clinical trials are underway to see if low-dose Naltrexone has other treatment benefits, especially for conditions involving the immune system.

Naltrexone/bupropion is marketed under the brand name Contrave. It is a weight-loss medication that acts in the brain to decrease food cravings and hunger.

In addition to having multiple uses, Naltrexone comes in various forms. The most common forms are tablets and injectables. An implantable form of Naltrexone has been tested but is not a first-line treatment method. Naltrexone is not currently available as a generic.

The form, dosage, method of administration, and frequency of administration of Naltrexone vary depending on what is being treated.

Alcohol Use Disorder

Naltrexone helps reduce cravings for alcohol and, therefore, prevents relapses. If you are diagnosed with AUD, your doctor will discuss your current alcohol use habits and verify whether you are physically dependent on alcohol or other substances.

After completing the alcohol detox process, Naltrexone can help block the euphoria or “buzz” associated with increased alcohol consumption. Alcohol and Naltrexone should not be taken together.

By blocking these positive feelings and cravings, Naltrexone can help you maintain your sobriety. According to the Substance Abuse and Mental Health Services Administration, most people with AUD take Naltrexone for three to four months.

Naltrexone gives your brain time to rewire its reward pathways. These pathways can become changed by long-term alcohol or drug use.

The words opioid with a needle and syringe

Opioid Use Disorder

Naltrexone also works well for OUD. Naltrexone binds and blocks opioid receptors in the brain to block the euphoric and sedative effects associated with opioid use. This helps reduce cravings and prevent relapses.

Because Naltrexone competes with opioids and displaces them from opioid receptors, it is important to wait a minimum of 7 days after taking a short-acting opioid or 10 to 14 days after taking a long-acting opioid before taking Naltrexone.

Naltrexone is not commonly used to treat OUD because it has low rates of patient acceptance. It is difficult for people to achieve complete abstinence from opioids before taking Naltrexone, and there is a high rate of nonadherence when using Naltrexone.

It is dangerous to take opioids and naltrexone together. Because Naltrexone gives your brain time to rewire its reward pathway, once you stop Naltrexone, your tolerance to opioids will be lower.

Taking the same or even lower doses of opioids after taking Naltrexone can cause life-threatening adverse effects.

Pain and Inflammation

Low-dose Naltrexone binds to and temporarily blocks mu-opioid receptors. When opioid receptors are blocked, your brain responds by ramping up naturally produced opioids.

While the effects of low-dose Naltrexone last about 4 to 6 hours, increased opioid levels can be present for 18 to 24 hours. A daily dose of low-dose Naltrexone can provide continuous pain relief.

Low-dose Naltrexone also reduces inflammation by blocking toll-like receptor (TLR)-4 receptors found on immune cells (macrophages). Inflammatory chemicals worsen pain by increasing swelling and redness. Reducing inflammation and pain can help control the symptoms associated with chronic pain disorders.

More research is needed to fully understand the benefits of low-dose Naltrexone, but this off-label use of Naltrexone is interesting because people can experience pain relief at much lower doses of Naltrexone.

Low-dose Naltrexone has a much lower potential to cause side effects than full-dose Naltrexone.

Weight Loss and Management

Naltrexone, combined with bupropion, is one of six FDA-approved medications for weight loss. Naltrexone/bupropion act in the brain to reduce cravings, increase satiety, and decrease hunger.

Naltrexone decreases food cravings in the same way as it helps reduce cravings for alcohol and opioids. Bupropion is believed to suppress hunger signals in the brain. It also acts as a mild stimulant. Together, Naltrexone and bupropion work better for weight loss than either medication on its own.

In an analysis of studies, the average weight loss when using naltrexone/bupropion was about 9 to 10 pounds per year. Naltrexone/bupropion have a moderate effect on body weight reduction. However, it also increases systolic blood pressure and heart rate.

What To Know Before Taking Naltrexone

Naltrexone is a prescription medication that has many known drug interactions and potential side effects. Talk to a medical practitioner online at Invigor Medical or in person to discuss your medical history and learn whether the risks versus benefits of Naltrexone are in your favor.

While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.

Is Naltrexone a Controlled Substance?

Leann Poston, M.D.

Dr. Leann Poston is a licensed physician in the state of Ohio who holds an M.B.A. and an M. Ed. She is a full-time medical communications writer and educator who writes and researches for Invigor Medical. Dr. Poston lives in the Midwest with her family. She enjoys traveling and hiking. She is an avid technology aficionado and loves trying new things.


  • An Introduction to Extended-Release Injectable Naltrexone for the Treatment of People with Opioid Dependence. Substance Abuse and Mental Health Services Administration. 2012. Accessed November 2023.
  • Naltrexone. Substance Abuse and Mental Health Services Administration. April 2022. Accessed November 2023.
  • Singh AK, Singh R. Pharmacotherapy in obesity: a systematic review and meta-analysis of randomized controlled trials of anti-obesity drugs. Expert Rev Clin Pharmacol. 2020 Jan;13(1):53-64. doi: 10.1080/17512433.2020.1698291. Epub 2019 Dec 22. PMID: 31770497.
  • Medications for Opioid Use Disorder: For Healthcare and Addiction Professionals, Policymakers, Patients, and Families: Updated 2021 [Internet]. Rockville (MD): Substance Abuse and Mental Health Services Administration (US); 2018. (Treatment Improvement Protocol (TIP) Series, No. 63.) Chapter 3C: Naltrexone. Available from:
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Published: Nov 4, 2023


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