Naltrexone: Medication for Alcohol Use Disorder

Medically reviewed by Joshua D Lee, MD, MSc


Nov 06, 2023

A pill bottle spilled over on an orange background.

What Is Naltrexone? 

Naltrexone is an effective prescription medication used to treat alcohol use disorder (AUD). Numerous studies have found naltrexone reduces heavy drinking, frequency of drinking, cravings for alcohol, and alcohol relapse. It is approved by the Food and Drug Administration (FDA). Oral naltrexone HCL (hydrochloride) is available in 50-milligram (mg) tablets and can be taken daily.

What Is Alcohol Use Disorder (AUD)?

AUD is a common medical condition that affects around 15 million people in the United States (1). People with AUD have trouble stopping drinking or controlling their alcohol use despite negative consequences from drinking alcohol. A person is diagnosed with AUD if they meet specific criteria as determined by a qualified medical professional.

AUD is not “alcoholism.” Alcoholism is a non-medical term that is no longer an official diagnosis in the United States. Whereas “alcoholism” has historically referred to the most serious cases of alcohol  misuse, an AUD diagnosis acknowledges that problems with alcohol exist on a spectrum, and each person has their own unique relationship with alcohol. AUD is diagnosed as mild, moderate, or severe depending on the number of symptoms a person has.

What Does Naltrexone Do? How Does It Help with AUD?

Naltrexone disrupts the chemical feedback loop that can make it difficult for a person to stop drinking once they have already consumed a few drinks. The medication treats AUD by binding to opioid receptors in the brain, blocking the euphoric and intoxicated feelings typically associated with drinking alcohol.

This euphoric feedback loop heightens cravings and can make controlling alcohol consumption very difficult for some people. Taking naltrexone for AUD allows people to not rely on willpower alone to drink less or stay abstinent from alcohol entirely.

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Does Naltrexone Help with Alcohol Cravings?

Yes. Several studies have found that naltrexone is effective as an anti-craving medication for alcohol. 

For example, one 2016 study found that among a group of people in a residential treatment program for AUD, those who took naltrexone saw a more rapid decrease in their cravings for alcohol than those who did not take naltrexone (2). 

Other research has found naltrexone leads to fewer thoughts about alcohol, less interest in daily drinking and heavy drinking, and reduced appeal of alcohol. While there are other approaches to reducing alcohol cravings, naltrexone is one of the most effective.

How Does Naltrexone Make You Feel?

Naltrexone does not have the potential for addiction. It’s not psychoactive, meaning you won’t have withdrawal symptoms if you stop taking it, and it won’t make you feel intoxicated or “high.”

As with any medication, there is a risk of side effects when taking naltrexone. These side effects are rare and usually mild. The most common side effects are: 

- Nausea

- Upset stomach

- Dizziness

- Headache

Naltrexone Half-Life: How Long Does Naltrexone Stay in Your System?

The half-life of oral naltrexone is between 4 and 13 hours.

Depending on what type of test is used, naltrexone can be detected in the body for up to 90 days after taking it:

Test typeDetection window
Urine testUp to 6 hours
Blood testUp to 24 hours
Saliva testUp to 24 hours
Hair follicle testUp to 90 days

Can You Overdose on Naltrexone?

Naltrexone is generally safe. You cannot overdose on it. However, taking too much naltrexone may cause side effects that require medical attention. Symptoms to watch for include:

- Blurred vision

- Hallucinations

- Confusion

- Severe vomiting

- Severe diarrhea

Some rare side effects need immediate medical attention. Get emergency help if someone has taken naltrexone and experiences any of the following: 

- Trouble breathing

- Seizure

- Collapses

- Becomes unconscious

Qualify For Treatment

FAQ: Naltrexone for Alcohol Use Disorder (AUD)

Is naltrexone addictive?

No. Naltrexone is not addictive and doesn’t cause withdrawal symptoms if you stop taking it.

What are the side effects of naltrexone?

Naltrexone is tolerated well by most people. If side effects do occur, the most common are nausea, upset stomach, dizziness, and headache.

How come I’ve never heard of medication as a treatment for alcohol use disorder?

Naltrexone and other medications to treat AUD are greatly underutilized. In part, this is because of the popularity of psycho-social interventions such as 12-step programs like Alcoholics Anonymous (AA), and the fact that only recently was AUD an official medical diagnosis. In addition to talking to a doctor, there are a number of alternatives to 12-step programs for alcohol addiction recovery.

To learn more about some of the key reasons you may not be familiar with medication-assisted treatment for AUD, see the Reference Library section below.

When do I take naltrexone? How long do I take it?

Some people take naltrexone every day. Others take it only before drinking, following an approach sometimes referred to as the Sinclair Method. Naltrexone is considered most effective when taken for longer than 3 months.  You can take it indefinitely. Discuss the right treatment length for you with your doctor.

Is medication alone enough to help me manage my drinking?

Some people are able to control their drinking on their own with just the help of naltrexone. However, it’s best to use naltrexone as part of a comprehensive plan for medication-assisted treatment that includes counseling, therapy, a 12-step program, or other support. Oar can help you find counseling and support options.

Can you drink on naltrexone?

Yes. Naltrexone does not react adversely with alcohol, so it is safe to drink alcohol in moderation while taking naltrexone. 

Naltrexone is an effective option both for people who want to stop drinking entirely and those who just want to drink less. 

Whether your goal is to remain abstinent from alcohol or just manage your relationship with alcohol, it’s important to follow your doctor's guidance for taking naltrexone.

Is naltrexone an opioid?

No, naltrexone is not an opioid. Naltrexone is an opioid antagonist, meaning it binds to opioid receptors in the brain, blocking the euphoric and intoxicated feelings typically associated with drinking alcohol.

Does naltrexone work right away?

A daily dose of naltrexone works in a few hours and is effective throughout that same day. 

When starting naltrexone treatment for AUD, your experiences with alcohol are likely to noticeably change within the first few weeks of taking naltrexone. This can mean fewer cravings for alcohol, fewer thoughts about alcohol, less interest in daily drinking and heavy drinking, and reduced appeal of alcohol.

Is 25 mg of naltrexone effective?

Taking 25 mg of naltrexone is not considered an effective dose for AUD and has not been well studied. 

That said, some people may find taking 25 mg of naltrexone lowers the risk of side effects and still helps control or eliminate drinking. Discuss the dose that’s right for you with your doctor.

Where can I learn more about naltrexone?

Click through the Reference Library below for resources, peer-reviewed studies, and articles on naltrexone.

Naltrexone Reference Library

National Institute on Alcohol Abuse and Alcoholism: Naltrexone information for patients

Food and Drug Administration: Naltrexone label

Substance Abuse and Mental Health Services Administration: Naltrexone clinical update

New England Journal of Medicine: “Naltrexone for the Management of Alcohol Dependence” case study and discussion

American Psychiatric Association: Why Is Naltrexone Not Used More to Treat Alcohol Use Disorder?

Robert Wood Johnson Foundation: Analysis of why naltrexone is underused as a treatment

About The Writer: Ian Landau is a journalist who's written extensively about health and wellness since 2010. He is also the author of The Hypochondriac's Handbook (Skyhorse, 2010).

About The Author

Josh Lee is a clinician and researcher with a focus on medication-assisted treatment of alcohol and opioid use disorders. He has conducted multiple clinical trials examining the use of naltrexone in primary care and other community settings. As a practicing physician, Josh helps manage the NYC Health + Hospitals/Bellevue addiction medicine clinic in adult primary care.

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