What is naltrexone?

Naltrexone is a prescription medication that helps people drink less or stop drinking. It works by blocking the pleasant “buzz” that alcohol gives you, so drinking feels less rewarding and cravings ease over time. It is not the old drug that makes you sick if you drink. That drug is disulfiram (Antabuse). Naltrexone is different: it quietly turns down the reward, which is why many people slowly lose the urge to keep drinking.

What is naltrexone?

Naltrexone is a medicine that blocks opioid receptors in the brain. Those are the same receptors that give you a rush of good feeling when you drink alcohol or take an opioid. When naltrexone sits on those receptors, alcohol can no longer trigger that reward. Doctors call this an “opioid antagonist,” which simply means it blocks, rather than activates, those signals.

It was first approved by the U.S. Food and Drug Administration in 1984 for opioid dependence, then in 1994 for alcohol dependence. It comes as a daily pill and as a once-a-month shot called Vivitrol. Naltrexone is not a narcotic, not a sedative, and not habit forming. You cannot get high from it, and you do not build a dependence on it. Because of that, it is not a controlled substance, and providers can prescribe it by telehealth.

What is naltrexone used for?

Naltrexone has two FDA-approved uses. The first is alcohol use disorder, where it lowers cravings and cuts down on heavy drinking days. The second is opioid use disorder, where it blocks the effect of opioids and helps prevent relapse after detox. In both cases it works the same way: it takes the reward out of the substance.

You may also hear about “low-dose naltrexone,” or LDN. That is a much smaller dose (around 1.5 mg to 4.5 mg) used off label for conditions like chronic pain and some autoimmune problems. It is a separate topic. This page is about the standard 50 mg dose used for alcohol. Naltrexone is also one half of a weight-loss pill (bupropion and naltrexone, sold as Contrave), but that is a different product with a different purpose.

How does naltrexone work?

When you drink, your brain releases endorphins, natural feel-good chemicals that create the warm, rewarding feeling that makes you want another drink. Naltrexone blocks the receptors those endorphins act on. So when you drink on naltrexone, the alcohol still enters your body, but the reward signal is muted. The drink is simply less satisfying.

Over time, that changes behavior. Your brain slowly learns that drinking no longer delivers the payoff it expects, so the pull to drink fades. Scientists call this pharmacological extinction. It does not force you to quit and it does not punish you for drinking. It gently removes the reason your brain keeps chasing alcohol.

Two ways to take it

There are two proven approaches, and your provider helps you pick the one that fits your goal.

The Sinclair Method is the best known targeted approach. You take naltrexone only on days you expect to drink, one hour ahead, and then let the medication strip the reward out of each drink. Used this way, many people find their drinking drops month after month. You can read more on our Sinclair Method guide.

How well does it work?

Naltrexone is one of the most studied medications for alcohol use disorder and a first-line treatment. A large 2014 review in JAMA found a number needed to treat of 12: for every 12 people treated, one extra person avoids a return to heavy drinking who would have relapsed without it.

It will not work the same for everyone, and it works best alongside support, whether that is counseling, a recovery community, or regular check-ins with a provider. But the evidence is clear: naltrexone reliably reduces heavy drinking days and helps people stay in control.

Naltrexone vs. naloxone

They sound alike and both block opioid receptors, but they do very different jobs. Naltrexone is long-acting maintenance treatment. Naloxone (Narcan) is a fast, short-acting rescue for an opioid overdose.

In short, naltrexone is for long-term recovery, and naloxone is for a crisis. See our full breakdown on naltrexone vs. naloxone.

Is naltrexone a controlled substance?

It is not habit forming, so you cannot become dependent on it. It is a plain prescription medication, which is why it can be started and managed through telehealth. For more detail, see is naltrexone a controlled substance.

Naltrexone dosage for alcohol

The standard dose for alcohol use disorder is 50 mg once a day by mouth. Some providers start at 25 mg for a few days to ease any early nausea, then move up to 50 mg. Others may go up to 100 mg. If you prefer not to take a daily pill, the monthly Vivitrol injection delivers 380 mg once every four weeks. Learn more on our naltrexone dosage guide and the naltrexone 50 mg tablet page.

Side effects and safety

Most people tolerate naltrexone well. The most common effects are nausea, headache, dizziness, tiredness, and trouble sleeping. They are usually mild and fade within the first week or two. Taking the pill with food helps settle the nausea.

At the standard 50 mg dose, naltrexone is gentle on the liver for most people, though your provider may check your liver with a simple blood test. See naltrexone side effects, what to avoid, drug interactions, and how long it stays in your system.

Who should not take naltrexone?

People with serious kidney or liver disease need extra care and monitoring. If you are pregnant, breastfeeding, or planning a pregnancy, talk with your provider first so you can weigh the benefits and risks together. A provider will review your full history before prescribing to make sure it is safe for you.

The bottom line

Naltrexone is a safe, non-addictive, FDA-approved medication that makes drinking less rewarding, so cravings fade and heavy drinking drops. It is not a controlled substance and it will not make you sick if you drink. You can take it every day to support quitting, or before drinking to slowly cut back with the Sinclair Method. It is one of the most effective tools we have for alcohol use disorder, yet very few people are ever offered it. If drinking has become a problem you want to change, naltrexone is worth asking a provider about.

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Frequently asked questions

Sources

• National Institute on Alcohol Abuse and Alcoholism (NIAAA). Alcohol Use Disorder in the United States. 2024 National Survey on Drug Use and Health (about 27.9 million people ages 12 and older).
• Substance Abuse and Mental Health Services Administration (SAMHSA). 2024 National Survey on Drug Use and Health (NSDUH), National Report.
• Jonas DE, et al. Pharmacotherapy for Adults With Alcohol Use Disorders in Outpatient Settings: A Systematic Review and Meta-analysis. JAMA. 2014;311(18):1889-1900 (number needed to treat = 12).
• American Academy of Family Physicians. Alcohol Use Disorder: Medication Options. American Family Physician, 2024.
• U.S. Food and Drug Administration. Naltrexone (ReVia) and naltrexone extended-release injectable (Vivitrol) prescribing information and approval history.
• Singh D, Saadabadi A. Naltrexone. StatPearls. National Library of Medicine.

This page is for education only and is not medical advice. Naltrexone is a prescription medication. Talk with a licensed provider about whether it is right for you.