How Long Does a Vivitrol Shot Last? Duration, Effectiveness, and What to Expect

"How long does a Vivitrol shot last?" is one of the most commonly searched questions about medication assisted treatment — and one of the most important ones to answer accurately. The answer is approximately 28 to 30 days, but the clinical story behind that number — how Vivitrol works, who it is right for, what it does and does not do, and what needs to be in place before you can start — is what actually determines whether the shot will be effective. This guide answers every question people in New Jersey commonly have about Vivitrol before starting treatment.

What Is Vivitrol?

Vivitrol is the brand name for extended-release injectable naltrexone — a monthly intramuscular injection used in the treatment of both opioid use disorder and alcohol use disorder. Naltrexone itself has been available in oral tablet form (brand name Revia) since the 1980s. Vivitrol — the injectable extended-release formulation — was FDA-approved in 2006 for alcohol use disorder and in 2010 for opioid use disorder.

The key clinical distinction between oral naltrexone and Vivitrol is adherence. Oral naltrexone requires a patient to take a pill every day — and research consistently shows that daily pill adherence is a significant challenge in addiction treatment. Vivitrol removes that challenge by delivering a full month of medication in a single injection administered by a healthcare provider. Once the shot is given, the medication is working whether or not the patient remembers to take it.

How Long Does a Vivitrol Shot Last?

A single Vivitrol injection provides approximately 28 to 30 days of therapeutic coverage — roughly one calendar month. The medication is formulated as microspheres that dissolve gradually after injection into the gluteal muscle (the upper outer quadrant of the buttock), releasing naltrexone steadily into the bloodstream over the course of the month.

The pharmacokinetic profile of Vivitrol shows a peak plasma concentration approximately two to three days after injection, followed by a gradual decline over the remaining weeks of the dosing period. Most patients receive their injection on a monthly schedule — returning to their provider every 28 days for the next dose. Missing or delaying an injection reduces coverage and increases the window of vulnerability to relapse.

How Does Vivitrol Work?

Naltrexone — the active ingredient in Vivitrol — is an opioid antagonist. It works by binding to opioid receptors in the brain with high affinity and blocking them from being activated by opioids. When a patient on Vivitrol uses an opioid, the opioid molecules cannot bind effectively to the blocked receptors — meaning the euphoric and reinforcing effects of the opioid do not occur. The opioid simply does not work in the way it normally would.

For alcohol use disorder, the mechanism is less completely understood but involves modulation of the brain's endorphin system. Alcohol triggers the release of endorphins — natural opioid-like compounds — which contribute to the pleasurable and reinforcing effects of drinking. Naltrexone blocks the opioid receptors that those endorphins act on, reducing the reward signal that drinking produces and — over time — reducing cravings and the motivation to drink.

It is important to understand what Vivitrol does not do. It does not produce euphoria. It does not create physical dependence. It does not prevent someone from using opioids or alcohol — it removes the reward. A person on Vivitrol who uses opioids will not experience the high they are seeking, but they can still be exposed to the toxic effects of the substance including overdose. Vivitrol is not a guarantee against overdose — it is a pharmacological tool that removes the reinforcement that drives continued use.

The Critical Requirement — Being Opioid-Free Before Starting Vivitrol

This is the most clinically important piece of information for anyone considering Vivitrol for opioid use disorder — and the one most commonly misunderstood. Because Vivitrol blocks opioid receptors with high affinity, administering it to someone who is still physically dependent on opioids will precipitate immediate and severe opioid withdrawal. This is not a mild discomfort — it is abrupt, intense, and medically significant.

Before starting Vivitrol for opioid use disorder, patients must be completely opioid-free — including free of all opioid-containing medications — for a minimum of 7 to 10 days. For patients coming off methadone the opioid-free period required is significantly longer — typically 10 to 14 days or more — due to methadone's long half-life. A urine drug screen and clinical assessment are conducted before the first injection to confirm that opioid clearance is sufficient.

This requirement means that for most patients with opioid use disorder, the pathway to Vivitrol begins with medically supervised detox — either at an inpatient detox facility or through a carefully managed outpatient detox process. Cherry Hill Recovery Center provides detox referral and coordinates placement for patients who need it, and coordinates the timing of the first Vivitrol injection with the receiving facility so the transition from detox into our PHP or IOP program — with Vivitrol in place — is seamless.

How Effective Is Vivitrol?

Multiple clinical trials have demonstrated Vivitrol's effectiveness for both opioid and alcohol use disorder when used as part of a comprehensive treatment program. The key phrase — part of a comprehensive treatment program — is not a disclaimer. It is the clinical reality. Vivitrol's effectiveness in trials is consistently higher when combined with behavioral treatment than when used in isolation.

Vivitrol for Opioid Use Disorder

The landmark clinical trial for Vivitrol in opioid use disorder — a randomized controlled trial published in The Lancet — found that patients receiving Vivitrol had significantly higher rates of confirmed abstinence from opioids, significantly more opioid-negative urine samples, and significantly lower rates of opioid craving compared to placebo. Dropout rates from treatment were also lower in the Vivitrol group. Critically, the study found that patients who successfully completed the detoxification requirement and initiated Vivitrol showed strong outcomes — underscoring how important proper preparation before the first injection is.

Vivitrol for Alcohol Use Disorder

For alcohol use disorder, clinical trials have shown Vivitrol significantly reduces heavy drinking days, increases the percentage of days abstinent, and reduces rates of return to heavy drinking compared to placebo. The medication appears particularly effective for reducing the reward signal associated with early drinking — making it easier for patients to stop after one drink rather than continuing to drink heavily. For alcohol use disorder specifically, Vivitrol does not require opioid clearance before starting — making it more immediately accessible than for opioid use disorder.

Who Is Vivitrol Right For?

Vivitrol is not the right choice for every patient with opioid or alcohol use disorder — and at Cherry Hill Recovery Center, it is never offered as a standalone prescription outside of a clinical treatment program. Whether Vivitrol is appropriate is a clinical decision made collaboratively between our medical team and the patient, based on a comprehensive assessment of the individual's situation.

Vivitrol tends to be a strong clinical fit for patients who have successfully completed detox and are fully opioid-free, who are highly motivated to maintain abstinence and want pharmacological support for that goal, who prefer a monthly injection over daily oral medication for adherence reasons, who have a reliable living situation and are engaged in ongoing PHP or IOP clinical programming, and who do not have active liver disease that would contraindicate naltrexone use.

Vivitrol may be less clinically appropriate for patients who are not yet fully opioid-free and ready to commit to complete abstinence from opioids, who have significant chronic pain being managed with opioid medications since Vivitrol will block the therapeutic effects of those medications, who have acute hepatitis or liver failure since naltrexone is metabolized by the liver, or who are pregnant or planning to become pregnant. Our clinical team reviews all contraindications individually before recommending Vivitrol.

Side Effects — What to Expect

Most patients tolerate Vivitrol well. The most commonly reported side effects include injection site reactions — tenderness, induration, or bruising at the injection site — which are generally mild and resolve within a few days, nausea in the days following injection, headache, fatigue, decreased appetite, and sleep disturbances.

The most significant potential adverse effect to be aware of is injection site necrosis — tissue damage at the injection site — which is rare but has been reported. Patients should notify their provider if they notice unusual pain, swelling, hardening, or skin changes at the injection site beyond normal post-injection tenderness.

Liver toxicity is a potential concern with naltrexone at very high doses — higher than the therapeutic dose used in Vivitrol — but liver function should be assessed before starting treatment and monitored periodically, particularly in patients with existing liver disease.

Vivitrol as Part of PHP and IOP at Cherry Hill Recovery Center

At Cherry Hill Recovery Center, Vivitrol is always offered as an integrated component of our PHP or IOP programs — never as a standalone prescription service. This is a deliberate clinical decision. The evidence consistently shows that Vivitrol's effectiveness is significantly higher when combined with structured behavioral treatment than when used in isolation. A monthly injection alone does not address the psychological, behavioral, and psychiatric dimensions of addiction that create the conditions for relapse.

When Vivitrol is initiated as part of our program, our medical team manages the injection schedule, monitors for side effects, assesses liver function as appropriate, and adjusts the treatment plan based on the patient's response. The injection is coordinated with individual therapy, group counseling, psychiatric evaluation, and relapse prevention planning — so the pharmacological support and the clinical work are aligned from the first dose.

Whether Vivitrol is the right MAT option for your situation — versus Suboxone, Sublocade, or no medication component — is something our clinical team discusses with every patient for whom MAT is being considered. If you are asking whether Vivitrol might be right for you, the best next step is a call to our admissions team. You can also verify your insurance in just a few minutes.

Frequently Asked Questions About Vivitrol

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