Naltrexone: A Clinical Guide for AUD and OUD

Medically reviewed by Dr. Richard A. Marasa, MD, MBA — Board Certified in Addiction Medicine, Emergency Medicine, and Internal Medicine. Over 40 years of clinical experience and 23+ years of personal recovery.

Naltrexone is a prescription, non-addictive medication approved by the U.S. Food and Drug Administration to treat alcohol use disorder (AUD) and to prevent relapse in opioid use disorder (OUD) after detoxification. It works by binding to opioid receptors in the brain without activating them — blunting the euphoric pull of alcohol and opioids so craving loosens its grip. According to the Substance Abuse and Mental Health Services Administration (SAMHSA), naltrexone is a core medication in modern medication-assisted treatment (MAT) and can be prescribed by any licensed practitioner without the special waiver historically required for buprenorphine.

This guide is written for patients, family members, and referring clinicians who want a clear, evidence-based picture of what naltrexone is, who it is for, how access works, and where it fits inside a real recovery plan. We do not recommend specific doses — dosing decisions belong to a prescriber who knows your history. What we can offer is the clinical context needed to have a productive conversation about whether naltrexone belongs on your treatment map.

What is naltrexone and how does it work?

Naltrexone is an opioid-receptor antagonist — a molecule that occupies the same brain receptors as opioids and alcohol's reinforcing neurochemistry, but without triggering the reward cascade they normally produce. Clinically, this means a person taking naltrexone who drinks alcohol feels less of the characteristic "buzz," and a person who uses opioids feels blunted or no effect at all (StatPearls, 2023). Over weeks, the weakened reinforcement loop reduces craving and the probability of return to heavy use. Naltrexone does not substitute for alcohol or opioids the way methadone or buprenorphine substitute for other opioids; there is no intoxication, no withdrawal from naltrexone itself, and no controlled-substance scheduling. It is taken daily as an oral tablet or monthly as an extended-release intramuscular injection marketed as Vivitrol (FDA, 2022). Because naltrexone is not a controlled substance, it does not show up on typical employment drug screens.

That pharmacology matters because it shapes who benefits and who should not use it. For alcohol, the goal is usually reduction of heavy drinking days and support of abstinence. For opioids, the goal is relapse prevention after a person has already completed detoxification — not induction into recovery. Understanding the difference prevents the most common mistake in naltrexone care: starting it too early in opioid treatment.

Mechanistically, naltrexone's effect on alcohol reinforcement is indirect. When a person drinks, endogenous opioid peptides — the brain's own feel-good molecules — release in the reward pathway. Naltrexone sits on those receptors so the release lands with less force. The subjective experience is often described by patients as drinking feeling "flat" or "not worth it." That blunted reward, repeated across drinking episodes, is what gradually weakens craving and extinguishes the behavioral loop. For opioids the blockade is more direct: opioids cannot activate a receptor naltrexone already occupies, so euphoria does not occur at all.

What conditions does naltrexone treat?

Naltrexone carries two primary FDA indications: alcohol use disorder and the prevention of relapse to opioid dependence following opioid detoxification (FDA, 2022). In alcohol use disorder, naltrexone is one of three medications approved by the FDA alongside acamprosate and disulfiram, and it is the most prescribed of the three. A 2023 systematic review published in the Journal of the American Medical Association pooled 118 randomized trials including 20,976 participants and concluded that oral naltrexone significantly reduces return to any drinking and return to heavy drinking compared with placebo. For opioid use disorder, extended-release naltrexone is one of three FDA-approved medications — alongside methadone and buprenorphine — and is a strong option for patients who have successfully completed withdrawal and want a non-opioid maintenance strategy.

Some clinicians also use naltrexone off-label for other compulsive behaviors, including gambling and binge-eating patterns, but these applications are not FDA-approved and are outside the scope of this guide. For substance use, the evidence base is mature and the indication is clear.

An important distinction: naltrexone is not a treatment for withdrawal. It does not ease tremor, sweats, anxiety, or seizure risk during alcohol or opioid withdrawal. Patients who need medically supervised withdrawal management should receive that care first — often with benzodiazepines for alcohol withdrawal, or buprenorphine tapers for opioid withdrawal — and then transition to naltrexone for relapse prevention once stabilization is complete. Skipping that step is the single most common cause of naltrexone failure in outpatient settings, usually because precipitated withdrawal drives a patient to discontinue in the first week.

Who qualifies for naltrexone?

Naltrexone is appropriate for adults with alcohol use disorder or opioid use disorder whose clinical picture fits a specific profile. The most important eligibility rule concerns opioids: a patient must be opioid-free for 7 to 10 days before receiving naltrexone, or the medication will trigger precipitated withdrawal — a sudden, severe withdrawal syndrome (StatPearls, 2023). This includes prescription opioids and tramadol, not only illicit substances. Your prescriber may confirm readiness with a naloxone challenge test. For alcohol use disorder, no washout period is required, but prescribers usually review liver function because severe hepatic impairment is a contraindication. Active opioid use, known hypersensitivity to naltrexone, and acute hepatitis or liver failure are the principal exclusions.

Qualifying does not mean everyone benefits equally. Naltrexone works best for people who are already motivated to reduce or stop drinking or using, who can engage in counseling or peer support, and who have a plan for what to do when cravings appear. It does not treat underlying mental-health conditions, trauma, or social instability — those need their own care. Many patients with substance use disorder also carry co-occurring diagnoses: depression, PTSD, generalized anxiety, or substance-induced anxiety disorder, and treating only the substance half of that picture usually disappoints. At Clear Steps Recovery, we screen for these factors during the intake so that a medication recommendation sits inside a realistic whole-person plan, not on top of it.

How is naltrexone taken — oral vs. Vivitrol?

Naltrexone is available in two forms. The oral tablet is taken daily and is the most common starting point for alcohol use disorder because it is inexpensive, widely covered by insurance and Medicaid, and easy to discontinue if side effects appear. Extended-release injectable naltrexone, marketed as Vivitrol, is administered intramuscularly by a clinician once every four weeks and provides continuous medication coverage without the need to remember a daily dose (FDA Vivitrol label, 2022). Vivitrol is FDA-approved for both AUD and OUD. A 2024 randomized trial comparing the two formulations in hospitalized AUD patients found both meaningfully reduced heavy drinking days over three months, with no statistically significant difference between oral and injectable in the primary outcome — meaning the choice is often less about efficacy and more about adherence risk, insurance coverage, and patient preference.

For patients leaving detox or early outpatient care, Vivitrol's monthly dosing is often attractive because it removes the daily decision. For patients who want to try a medication without long-term commitment, the oral form lowers the stakes of the first 30 days. Your prescriber will weigh both with you.

Duration matters too. Current best practice, supported by guidance from the American Society of Addiction Medicine, is to continue naltrexone for a minimum of 3 to 6 months in the stabilization phase, with many patients benefiting from 12 months or longer before any taper attempt. Earlier discontinuation is the most common reason naltrexone "doesn't work" in real-world practice: trials show the medication's effect is dose-dependent on adherence, so patients who stop after a few weeks lose most of the benefit. Discussing duration openly with a prescriber at the start sets realistic expectations.

What are the side effects and risks?

Most patients tolerate naltrexone well. The most commonly reported side effects — each occurring in greater than 10% of patients — are nausea, headache, dizziness, fatigue, nervousness, insomnia, and mild injection-site reactions for Vivitrol (StatPearls, 2023). These are usually mild, peak in the first 1 to 2 weeks, and resolve on their own. Serious adverse events are uncommon. The FDA carries a warning about hepatotoxicity at doses well above standard therapeutic ranges, which is one reason prescribers avoid naltrexone in people with severe liver disease and check baseline liver enzymes before starting. The most dangerous risk is specific to opioid use disorder patients: because naltrexone blocks opioid receptors, tolerance drops quickly, and relapse with previous-use-level doses of opioids can cause fatal overdose. Every patient starting naltrexone for OUD should receive overdose-prevention counseling and a naloxone kit.

Naltrexone does not cause sedation, euphoria, or dependence. It can be stopped without tapering. If you have planned surgery requiring opioid pain control, tell your surgical team in advance — naltrexone will block the analgesic effect of standard opioids, and a non-opioid pain plan or a supervised pause may be needed.

How effective is naltrexone?

Naltrexone has one of the most robust evidence bases in addiction medicine. The 2023 JAMA systematic review of 118 trials — the largest analysis to date — found that oral naltrexone at 50 mg/day produced a number needed to treat (NNT) of 18 to prevent one return to any drinking and an NNT of 11 to prevent one return to heavy drinking. Translated: out of every 11 patients treated, one additional person avoids heavy drinking who would have relapsed on placebo. Those numbers are comparable to many widely used cardiovascular preventive medications. For opioid use disorder, a large trial funded by the National Institute on Drug Abuse (NIDA) showed that extended-release injectable naltrexone produced roughly 74% opioid-negative urine samples versus 56% with counseling alone at six months — a meaningful clinical gap.

Effectiveness is not a guarantee of individual outcome, and a single medication rarely carries recovery on its own. Patients who combine naltrexone with counseling, peer support, and a stable environment generally do better than those who rely on medication alone. Think of naltrexone as a pharmacologic assist, not a finished treatment. The patients who have written the most compelling real recovery stories from MAT participants we have worked with consistently describe medication as one tool inside a larger change — therapy they engaged in, a sponsor or peer group, a new routine, repaired relationships.

One practical note: some patients report that cravings return in the first 30 to 60 days after starting naltrexone. This is often mistaken for medication failure when it is actually the normal arc of early recovery — cravings are strongest in the early weeks regardless of pharmacology. The medication's job is to lower the ceiling of those cravings and reduce the neurochemical reward if a slip occurs, not to eliminate urges. Working with a therapist to reframe that timeline usually improves retention.

What does a real naltrexone treatment plan look like?

A clinically sound naltrexone plan starts with a full evaluation, not a prescription. At Clear Steps Recovery, that means a psychiatric and medical history, a review of current medications, baseline liver function labs, and an honest conversation about goals — abstinence, moderation, harm reduction, or re-stabilization after a slip. For patients whose primary issue is opioids, we confirm the 7 to 10 day opioid-free window and often bridge through supervised withdrawal management first. For patients with alcohol use disorder, we pair the medication with our medication-assisted treatment (MAT) program, which layers individual therapy, group work, and — where appropriate — co-occurring mental-health treatment. We track what is working and what is not at regular intervals, and we adjust. The goal is not to keep someone on naltrexone indefinitely. The goal is sustained recovery, with medication as scaffolding for as long as scaffolding helps.

This is the approach the NIDA Principles of Drug Addiction Treatment consistently describe: medication combined with counseling and whole-person care outperforms either alone.

Why is naltrexone so underused — and how do I access it?

Despite decades of evidence, naltrexone remains one of the most under-utilized medications in medicine. National data from the Substance Abuse and Mental Health Services Administration and the National Institute on Alcohol Abuse and Alcoholism show that fewer than 2% of Americans with alcohol use disorder receive any FDA-approved medication in a given year, and a 2022 multisite survey in Frontiers in Psychiatry identified the main barriers as prescriber unfamiliarity, persistent stigma, and the assumption that alcohol use disorder is a willpower problem rather than a treatable medical condition. Payer coverage has improved — most commercial insurance plans, New Hampshire Medicaid, and Massachusetts MassHealth now cover both oral naltrexone and Vivitrol — but navigating the prior authorization maze without a treatment team is hard.

Access is simpler than most people expect. A primary-care physician can prescribe oral naltrexone in many states, and addiction-medicine programs like Clear Steps Recovery can coordinate the whole plan: evaluation, prescription, counseling, lab monitoring, and insurance navigation. In New Hampshire, the NH Doorway system and 211 can also route people to medication-ready providers. In Massachusetts, the Bureau of Substance Addiction Services maintains a directory of MAT-enabled programs through MA DPH. For a broader view of FDA-approved options beyond naltrexone — including acamprosate, buprenorphine, methadone, and others — see our companion guide on the top medications for addiction treatment.

When is naltrexone not the right choice?

Naltrexone is not for everyone. Patients who need opioid-agonist therapy for severe opioid use disorder — where blocking receptors without a substitute risks destabilization and overdose — are generally better served by methadone or buprenorphine, per SAMHSA TIP 63. Patients in the middle of an opioid withdrawal episode should not start naltrexone until the 7 to 10 day window has cleared. People with active hepatitis, decompensated liver disease, or acutely abnormal liver enzymes need alternative plans. Pregnant patients and those breastfeeding should discuss alternatives with a specialist — the data are limited. And patients whose core problem is untreated depression, PTSD, or chronic pain often need those conditions addressed in parallel; naltrexone helps with craving and reinforcement, not with the upstream drivers.

Being "not a candidate today" is not the same as being "not a candidate ever." Many patients start with stabilization, treat the co-occurring condition, and return to a naltrexone conversation later. The key is an honest evaluation — not a one-size-fits-all protocol.

What about naltrexone and the Sinclair Method?

The Sinclair Method is a protocol popularized in Europe in which patients take naltrexone approximately one hour before drinking — rather than daily regardless of drinking — with the goal of pharmacological extinction of the reinforcement loop. Proponents report strong outcomes, and there is a small but interesting evidence base behind the approach. However, the Sinclair Method is an off-label application of naltrexone in the United States, not an FDA-approved dosing schedule. A minority of U.S. clinicians offer it; most adhere to the daily-dosing model used in pivotal trials. Patients curious about Sinclair should raise it with a prescriber who is familiar with both approaches. It is not a substitute for treatment of moderate-to-severe alcohol use disorder, and it requires honest self-report and outpatient monitoring to be used safely. We mention it here because patients sometimes arrive at Clear Steps Recovery asking about it; it is a real option inside a narrow slice of the AUD population, not a replacement for evidence-based MAT.

Naltrexone in New Hampshire and Massachusetts: what local patients should know

Coverage and access look slightly different in the two states Clear Steps Recovery serves. In New Hampshire, NH Medicaid, Medicare, and all major commercial plans cover oral naltrexone and Vivitrol without prior authorization in most cases; several New England-based commercial carriers also cover the Vivitrol injection with a medical-benefit billing code, which can be more patient-friendly than pharmacy-benefit models. The NH Doorway network and the statewide Addiction Crisis Line (211) connect patients to MAT-ready providers within 48 hours, and our Londonderry intake team can handle the medication handoff directly. In Massachusetts, MassHealth covers both formulations, and MA DPH requires licensed outpatient programs offering our level of care to use the term "Evening Treatment" rather than IOP on consumer-facing materials; our Needham location participates in that framework and can coordinate both the medication and the counseling in one plan. If you are weighing a different program, ask two questions: does the program prescribe naltrexone on-site, and does it integrate counseling with the pharmacologic plan? If either answer is no, coordination will fall to you.

Getting started with naltrexone at Clear Steps Recovery

If you are in New Hampshire, Massachusetts, or northern New England and you want to know whether naltrexone belongs in your recovery plan, Clear Steps Recovery can help you find out. Our clinical team — led by Medical Director Dr. Richard Marasa, Board Certified in Addiction Medicine with more than 40 years of clinical experience and 23+ years of personal recovery — provides medically-supervised evaluations, prescribing, and integrated outpatient care that wraps medication inside real therapy, real peer support, and a real aftercare plan.

Call (603) 769-8981 for our Londonderry, NH program, or (781) 765-0001 for our Needham, MA location. Admissions is available 24/7 for a confidential assessment, and we will verify insurance benefits before the first visit so there are no surprises. If the conversation reveals that naltrexone is not the right fit, we will tell you plainly — and help you find what is.

Recovery is hard work. The right medication, inside the right treatment plan, can make the work possible. That is all naltrexone is, and it is a great deal.