If you or someone you care about has been prescribed Vivitrol — or you're weighing it as an option — you probably have a handful of very specific questions: What does the shot actually feel like? How is it different from the naltrexone pill? What are the real risks? And is it worth the cost? Those are exactly the right questions, and this page answers all of them.

Vivitrol is the brand name for extended-release naltrexone (XR-NTX), a 380mg injection given once a month into the gluteal muscle. The FDA approved it for alcohol use disorder in 2006. If you've seen it referred to as extended-release naltrexone, XR naltrexone, depot naltrexone, or naltrexone injection, those all mean the same thing. The active medication is identical to the daily naltrexone tablet — the only difference is how it's delivered and how long it stays active in your body.

How Vivitrol works in the brain

Naltrexone is a mu-opioid receptor antagonist. That's a technical way of saying it locks onto the brain's opioid receptors and blocks them — without activating them. This matters for alcohol use disorder because of how alcohol produces its rewarding effects.

When you drink, alcohol triggers the release of endorphins, which bind to opioid receptors and generate that pleasurable, relaxed feeling. Naltrexone sits in those receptors and blocks the signal. The reward from drinking is blunted. Over time, that reduced reinforcement makes it easier to drink less or stop entirely — cravings tend to diminish because the brain is no longer getting the payoff it expects.

A few things Vivitrol does not do: it doesn't make you feel sick when you drink (that's disulfiram/Antabuse), it doesn't produce sedation or a high, and it doesn't cause physical dependence. In someone who isn't opioid-dependent, you won't feel it working at rest — its effect becomes apparent mainly when alcohol is consumed.

How Vivitrol compares to the daily naltrexone pill

Both forms contain naltrexone and work through the same mechanism. The differences come down to delivery, adherence, cost, and flexibility.

The adherence argument is the core clinical case for Vivitrol. Daily pill adherence in AUD treatment is a well-documented challenge. Someone who misses several days of oral naltrexone loses its protective effect during exactly the period when they may be most vulnerable. With Vivitrol, the medication is working for the full month regardless of what happens each morning. That's a structural advantage, not a motivational one.

The cost reality deserves equal honesty. A roughly 40-to-1 price difference — $1,500 versus $30 — is not a minor consideration. For many people, oral naltrexone is the appropriate first choice simply because it's accessible. That conversation should happen openly with every person considering Vivitrol.

The irreversibility is a meaningful clinical fact. Oral naltrexone can be stopped the same day if something goes wrong. Vivitrol cannot. If you have a serious adverse reaction after the injection, the medication stays in your system for the full month. This is one reason many clinicians recommend trying the oral pill first.

What the research shows

The pivotal trial supporting Vivitrol's FDA approval for AUD was published by Garbutt and colleagues in 2005. Patients receiving the 380mg monthly injection had significantly fewer heavy drinking days compared to placebo — the core efficacy signal that led to approval.

The broader evidence base for naltrexone in AUD is anchored by the COMBINE study (Anton et al., JAMA, 2006), which established that naltrexone — with or without intensive behavioral therapy — meaningfully reduces heavy drinking days and increases abstinence rates compared to placebo. Systematic reviews of naltrexone for AUD have consistently found clinically meaningful reductions in heavy drinking episodes. Real-world data from VA healthcare settings generally support the adherence advantage of extended-release formulations over daily oral dosing, particularly in patients with documented non-adherence to oral therapy.

The honest summary: Vivitrol produces clinically meaningful reductions in heavy drinking and increases in abstinence days compared to placebo. In head-to-head comparisons with oral naltrexone, effect sizes are generally similar — the real-world advantage of Vivitrol shows up most clearly in populations where daily adherence is a genuine barrier. It works best as part of a comprehensive plan that includes counseling and support, not as a standalone fix.

The opioid washout requirement — the most important safety point

Before your first Vivitrol injection — or any injection after a gap during which opioid use may have occurred — you must be completely free of opioids. This is not a formality. It is the single most critical safety requirement in Vivitrol prescribing.

Naltrexone has extremely high affinity for opioid receptors — higher than most opioids themselves. If opioids are still present in your body when naltrexone is administered, it will displace them from receptors and trigger precipitated withdrawal. This is not ordinary opioid withdrawal. It is sudden, severe, and can begin within minutes of the injection. Symptoms include intense nausea and vomiting, severe abdominal cramping, profuse sweating, and extreme agitation. Unlike ordinary withdrawal, it cannot be managed by taking an opioid — the naltrexone blocks those receptors for weeks.

The minimum opioid-free periods before injection:

• Short-acting opioids (heroin, oxycodone, hydrocodone, morphine): 7–10 days
• Buprenorphine (Suboxone, Subutex): 7–10 days after the last dose
• Methadone: 10–14 days minimum, often longer depending on dose
• Extended-release opioid formulations: consult prescribing information for specific guidance

Before the first injection, a clinician should take a thorough opioid use history, obtain a urine drug screen, assess for signs of withdrawal or intoxication, and consider a naloxone challenge test if opioid use history is uncertain.

The washout window is where patients are most often lost. The gap between agreeing to treatment and actually receiving the first injection can become a significant barrier for people who are also managing opioid dependence. If that applies to you or someone you're supporting, medically supervised detox or a structured bridge protocol is often needed before Vivitrol can begin. Programs without a clear washout protocol tend to see high dropout rates before the first injection is ever given.

What the injection involves

Vivitrol is not a standard intramuscular shot. It requires specific preparation and technique, and it must be administered by a healthcare professional — it cannot be self-administered.

Preparation and storage. Vivitrol comes as a powder that must be reconstituted with a supplied diluent immediately before use. It requires refrigeration (36°F–46°F) and can only be kept at room temperature for up to 7 days before administration. The medication should reach room temperature before injection if it's been stored cold.

The injection site. Vivitrol goes deep into the gluteal muscle — not the deltoid, not subcutaneous tissue. A 2-inch needle is typically used to ensure proper depth, particularly for patients with higher body mass. An injection that's too shallow significantly increases the risk of injection site reactions and may affect how the medication is absorbed.

Site rotation. The left and right gluteal muscles should alternate with each monthly dose to reduce tissue damage and nodule formation at any single site.

What to expect at the site. Pain, tenderness, hardening (induration), and bruising at the injection site are common and typically resolve within a few weeks. Nodule formation can occur. Rare but serious injection site reactions — including tissue necrosis requiring surgical management — have been reported. You should contact your provider about any injection site changes that worsen rather than improve over time.

Side effects to know about

The most common side effects of Vivitrol are:

• Injection site reactions (pain, induration, nodule) — the most frequently reported
• Nausea — particularly in the first few days after injection
• Headache
• Fatigue
• Decreased appetite
• Dizziness

Beyond the common side effects, a few specific risks deserve attention:

Liver concerns. Naltrexone carries a black box warning for hepatotoxicity at high doses. At the doses used for AUD, serious liver injury is rare, but liver function tests should be monitored — especially if you have pre-existing liver disease. Vivitrol is not recommended for people with acute hepatitis or liver failure.

Mood changes. Cases of depression, including suicidal ideation, have been reported in people receiving naltrexone. The causal relationship isn't fully established, but mood should be monitored in the weeks following each injection. If you have a history of depression, closer follow-up is warranted.

Opioid pain management. Because Vivitrol blocks opioid receptors, standard opioid pain medications won't work effectively while the medication is active. This matters for surgical planning and emergency pain management. Carrying a medical alert card indicating you're on naltrexone is strongly recommended. In emergencies, higher opioid doses may be needed to overcome the blockade — which carries its own risk once the naltrexone eventually wears off.

Allergic reactions. Hypersensitivity reactions, including anaphylaxis, have been reported. Standard emergency equipment should be available wherever injections are given.

Who is Vivitrol the better choice for?

Vivitrol tends to be the stronger clinical option in these situations:

• Documented adherence problems with oral naltrexone. If you've tried the daily pill and missed doses consistently, the structural adherence advantage of monthly injection directly addresses the mechanism of failure.
• Criminal justice and supervised treatment contexts. Drug courts, probation programs, and reentry settings frequently use Vivitrol because a monthly injection provides verifiable, supervised medication delivery in a way that daily pills cannot. This is a real and legitimate advantage in those settings — though it also raises consent concerns discussed below.
• Patient preference for monthly dosing. Some people find that a monthly injection feels less like a daily reminder of their diagnosis. Fewer medication-related decisions can feel genuinely freeing. That's a valid, patient-centered reason to choose Vivitrol.
• Chaotic daily schedules or complex medication regimens. People with unstable housing or many competing demands may benefit from the simplicity of once-monthly treatment as part of a broader medication-assisted treatment plan.

When the oral pill is the better starting point

Oral naltrexone (50mg daily) remains the appropriate first choice in many situations:

• First-time naltrexone trial. Starting with the oral form lets you assess tolerability and response before committing to the higher cost and irreversibility of the injection.
• Cost sensitivity. When insurance coverage is uncertain or absent, oral naltrexone is far more accessible at roughly $30/month.
• Needle phobia. A meaningful number of people will decline injectable treatment due to fear of needles. This is a valid reason to use oral naltrexone, full stop.
• Need for dose flexibility. Oral naltrexone can be titrated, paused, or stopped immediately. In patients whose clinical situation may change quickly — including those with uncertain opioid use patterns — that flexibility is a safety advantage.
• Preference for agency. Some people want to be able to stop the medication quickly if needed. Oral naltrexone allows that; Vivitrol does not.

Cost and insurance coverage

Vivitrol costs approximately $1,500 per monthly injection at wholesale acquisition cost. With administration fees, total monthly costs can exceed $1,600–$1,800 in many settings. Generic oral naltrexone costs approximately $25–$40 per month.

Most commercial insurance plans cover Vivitrol, typically requiring prior authorization — a process that can take days to weeks and usually requires documentation of a diagnosis, previous treatment attempts, and clinical justification. Medicaid coverage varies significantly by state; some programs require step therapy (trying oral naltrexone first). Medicare Part D covers Vivitrol subject to plan-specific formulary placement.

Alkermes, the manufacturer, operates a patient assistance program for uninsured or underinsured patients who meet income eligibility criteria. Many drug court and reentry programs access Vivitrol through state or federal grant funding, which can significantly reduce or eliminate patient cost. Exploring all medication treatment options alongside their coverage implications is worth doing before a decision is made.

Vivitrol in criminal justice settings — what you should know

Vivitrol has been widely adopted in drug courts, reentry programs, probation supervision, and pre-trial diversion. Monthly injection provides verifiable adherence in a way daily pills cannot — a drug court judge or probation officer can confirm an injection was received; they can't confirm a pill was swallowed each morning.

But there's a legitimate concern here worth naming directly. In many criminal justice settings, agonist therapies like methadone and buprenorphine face significant stigma and regulatory barriers. Vivitrol, as a non-controlled substance with no abuse potential, faces fewer institutional obstacles. The result is that in many programs, Vivitrol isn't chosen from a menu of options — it's the only option offered.

When participation in a drug court or release from incarceration is contingent on receiving Vivitrol injections, the voluntariness of that consent is legitimately questionable. People in these settings have the right to know what medications are available to them — including agonist therapies — even if those therapies aren't offered through the specific program. Informed consent for Vivitrol should include an honest discussion of alternatives, and clinicians working in these settings should advocate for access to the full range of evidence-based treatments.

What happens if you miss an injection?

If a monthly Vivitrol injection is missed or delayed, re-inject as soon as possible. There's no clinical reason to wait for a specific calendar date — the goal is to restore consistent receptor blockade quickly.

No repeat opioid washout is required if you remained opioid-free during the gap. The washout requirement applies to initiating naltrexone in someone who is opioid-dependent — not to re-dosing a patient who has been maintained on Vivitrol and hasn't used opioids.

If opioid use occurred during the missed-dose period, clinical assessment is required before re-injection, and the same safety protocol as initial dosing applies. Programs should have proactive outreach — phone calls, text reminders, case manager contact — to minimize the gap between scheduled and actual injection dates. The longer the gap, the greater the risk of relapse and the greater the chance that opioid use during the gap will complicate re-initiation.