Medically Reviewed By

Brittany Kowalski, LCSW, ACS, CCS

Clinical Director, Speranza Behavioral Health · Last clinically reviewed July 2026

Vivitrol (Naltrexone) for Alcohol and Opioid Addiction: How It Works and What to Expect

Vivitrol is one of the most significant advances in addiction medicine of the past two decades. As a once-monthly injectable form of naltrexone, it solves one of the most persistent challenges in addiction treatment: daily medication compliance. When someone has to take a pill every day to support their recovery, the pill can be forgotten, skipped, or deliberately not taken in anticipation of use. When a monthly injection has been administered, that decision has been made for 30 days.

This guide covers exactly how Vivitrol works, who it's appropriate for (and who it isn't), what to expect when starting, and how it's integrated into treatment at Speranza Behavioral Health.

What Is Vivitrol?

Vivitrol is the brand name for extended-release injectable naltrexone — a once-monthly intramuscular injection. The active ingredient is naltrexone, an opioid antagonist that completely blocks opioid receptors.

Naltrexone has been FDA-approved for:

• Alcohol use disorder (since 1994 in oral form; 2006 as Vivitrol injection)
• Opioid use disorder (oral naltrexone approved 1984; Vivitrol injection approved 2010)

How Vivitrol Works in the Brain

Naltrexone works by completely blocking opioid receptors throughout the brain — with very high binding affinity. This blocking effect has two clinical consequences:

For opioid use disorder: If someone on Vivitrol uses opioids (heroin, fentanyl, oxycodone), the opioids cannot bind to their receptors — and no euphoric effect is produced. The drug has no effect. This removal of the reward eliminates the reinforcement that drives continued use.

For alcohol use disorder: The brain's endogenous opioid system plays a significant role in the pleasurable effects of alcohol. By blocking opioid receptors, Vivitrol blunts the rewarding effects of alcohol and significantly reduces cravings. Multiple randomized controlled trials show Vivitrol reduces heavy drinking days by approximately 25% compared to placebo.

The once-monthly injection eliminates the daily compliance challenge entirely — once the injection is given, the patient doesn't need to decide each day whether to take their medication.

Who Is Vivitrol Right For?

Appropriate candidates:

For opioid use disorder:

• Individuals who have completed opioid detox and are fully opioid-free (critical requirement — see below)
• People who prefer not to use an opioid-based medication (buprenorphine) due to personal values, job requirements, or past experience
• People who have previously used buprenorphine and want to transition off opioid-based MAT
• People in justice-involved settings where buprenorphine access is restricted

For alcohol use disorder:

• Individuals who are medically detoxed and committed to abstinence
• People with moderate-to-severe AUD who have strong motivation but need pharmacological support
• People who have relapsed despite behavioral treatment alone

Critical requirement for opioid use disorder:

Before starting Vivitrol for opioid use disorder, the person must be completely opioid-free for a minimum of 7–10 days (longer for long-acting opioids like methadone — typically 10–14 days). If Vivitrol is given while any opioids remain in the system, it will precipitate immediate, severe withdrawal — because the naltrexone displaces opioids from receptors abruptly. This is medically manageable but extremely uncomfortable and must be avoided.

Our team performs a naloxone challenge test or confirms full detox before initiating Vivitrol.

What to Expect When Starting Vivitrol

The injection: Vivitrol is administered as an intramuscular injection (into the gluteal muscle — the buttock). The injection itself takes less than a minute. The most common side effects at the injection site are soreness, tenderness, and occasionally a lump that resolves over weeks.

Side effects: The most common systemic side effects of Vivitrol are:

• Nausea (most common in the first injection; typically diminishes with subsequent doses)
• Fatigue
• Decreased appetite
• Headache
• Injection site reactions

Duration: Each injection provides consistent therapeutic naltrexone blood levels for approximately 30 days, at which point the next injection is due.

Monitoring: Regular urine drug screens confirm abstinence. Our psychiatric and medical team monitors response and side effects over the course of treatment.

Vivitrol vs. Suboxone: How to Choose

A common question is whether Vivitrol or Suboxone (buprenorphine) is the better option for opioid use disorder. The honest answer: both work, and the "better" option depends on the individual's clinical situation:

| | Vivitrol | Suboxone | |---|---|---| | Opioid content | None (not an opioid) | Partial opioid agonist | | Detox required first | Yes (7–14 days) | No (start in mild withdrawal) | | Overdose protection | Yes (blocks opioids) | Yes (ceiling effect) | | Frequency | Once monthly injection | Daily sublingual | | Abuse potential | None | Low (with naloxone added) | | Evidence base | Strong | Very strong | | Good for | Motivated patients, post-detox, certain professions | Most OUD presentations, including active use |

Our clinicians discuss both options thoroughly during the assessment and treatment planning process.

Vivitrol at Speranza Behavioral Health, Woodbury NJ

Vivitrol injections are administered by our medical team as part of our integrated MAT program within PHP and IOP. Most insurance plans cover Vivitrol as a pharmacy or medical benefit.

Call (866) 814-0126 for a free assessment and to discuss whether Vivitrol is right for you.

Related Reading:

• What Is Medication-Assisted Treatment?
• Suboxone Treatment in South Jersey
• Opioid Addiction Treatment in NJ

About the Author

Brittany Kowalski

Brittany Kowalski is a licensed clinical social worker (LCSW) and behavioral health advocate at Speranza Behavioral Health in Woodbury, NJ. With over a decade of experience in addiction recovery and mental health treatment, she specializes in dual diagnosis care, trauma-informed therapy, and evidence-based outpatient programs serving South Jersey communities.