Quick Summary
Vivitrol is the brand name for extended-release naltrexone, a once-a-month shot that blocks opioid receptors instead of activating them. The FDA label covers two uses: preventing a return to opioid use after detox, and treating alcohol dependence in people who can stop drinking before the first dose. The start needs special care, because opioids still in the body can trigger severe withdrawal. This guide covers how Vivitrol works, who it may fit, what the research shows, and the safety points that often get skipped.
Key Takeaways
- Vivitrol is a 380 mg naltrexone injection given by a health care provider about every 4 weeks. It blocks opioids and is not itself an opioid.
- For opioid use disorder, the label calls for at least 7 to 10 days opioid-free before the first shot. Starting too soon can cause precipitated withdrawal severe enough to need hospital care.
- In a large head-to-head trial, fewer people could start Vivitrol than buprenorphine-naloxone (72% vs. 94%). Among people who did start, relapse rates were similar.
- Opioid tolerance is lower after detox, and the shot’s blockade fades toward the end of each month. Using opioids near the end of a dosing period, after a missed dose, or after stopping can cause a fatal overdose. Keep naloxone available and call 911.
- Vivitrol has real risks, including severe injection site reactions, liver problems, and mood changes. It is meant to be paired with counseling, and every provider you see should know you are on it.
What Vivitrol Is
Naltrexone is an opioid antagonist, which means it sits on the opioid receptors and blocks them without turning them on. The FDA lists three medications approved for opioid use disorder: buprenorphine, methadone, and naltrexone. NIDA explains that, unlike the other two, naltrexone works solely by blocking opioid receptors. SAMHSA adds that it is not an opioid, is not addictive, and does not cause withdrawal when you stop.
The Vivitrol label lists two uses: preventing a return to opioid use after opioid detox, and treating alcohol dependence in people who can stop drinking in an outpatient setting before treatment starts. It also says Vivitrol should be part of a full treatment program with psychosocial support, not a stand-alone fix.
How the Shot Works
A health care provider gives Vivitrol as a deep injection into the buttock muscle. The label dose is 380 mg every 4 weeks, alternating sides each time. Taking oral naltrexone first is not required. Blood levels peak about 2 hours after the shot and again 2 to 3 days later, then start to decline around day 14. The label says the opioid blockade lasts about 28 days, which is why the monthly schedule matters. If you miss a dose, get the next one as soon as possible.
Because Vivitrol blocks opioid receptors, opioid-containing medicines may not work for you. The label names cough and cold remedies, antidiarrheal products, and opioid pain medicines.
Starting Vivitrol: Why the Opioid-Free Window Matters
Starting needs special attention because too little opioid-free time can cause precipitated withdrawal. If opioids are still in the body, the shot can trigger it, and it hits suddenly and can be severe. The label says it can be severe enough to require hospitalization, and some postmarketing cases needed intensive care. The label asks for:
- At least 7 to 10 days opioid-free before the first injection after short-acting opioids. Tramadol counts as an opioid here. SAMHSA gives a similar guide: 7 days after short-acting opioids and 10 to 14 days after long-acting ones.
- Up to 2 weeks of vulnerability for people switching from buprenorphine or methadone.
- An honest account of your last opioid use. There is no completely reliable way to confirm an adequate opioid-free period. A naloxone challenge test can help, but some people have had precipitated withdrawal despite a negative urine screen or a passed challenge.
NIDA says naltrexone is typically started after a person has completely stopped taking other opioids. Supervised care can monitor withdrawal and help judge readiness, but no method completely confirms that the opioid-free period is long enough. The opioid detox page explains what supervised detox involves. NIDA also notes that research it supports suggests a faster start can work, but the label says a quicker transition belongs in a medical setting with close monitoring.
If you drink and also use opioids, say so. The label says precipitated withdrawal has happened in people treated for alcohol whose prescriber did not know about their opioid use.
Vivitrol for Alcohol Use Disorder
NIAAA lists three medications approved for alcohol use disorder: naltrexone, acamprosate, and disulfiram. Naltrexone comes as a pill or an injection and helps reduce the urge to drink.
The label describes a 24-week placebo-controlled trial in outpatients. People on the 380 mg dose had a bigger drop in heavy drinking days than people on placebo, but who benefited matters. The effect stood out in the 8% of participants who had stopped drinking the week before their first dose. They had larger reductions in drinking days and were more likely to stay fully abstinent. The same effect was not evident in the 92% who were still drinking at the start. Separately, the label says patients should not be actively drinking at the first injection.
Vivitrol also does not ease alcohol withdrawal. Stopping heavy drinking suddenly can be dangerous, and Vivitrol is not a substitute for medically supervised alcohol withdrawal care, so talk with a clinician first. The alcohol rehab page covers the options.
What the Research Shows
In the 24-week placebo-controlled opioid trial described in the label, 36% of people on Vivitrol stayed opioid-free at every weekly visit from week 5 to week 24, compared with 23% on placebo. More people on Vivitrol also stayed in the study.
X:BOT measured both how many people could start treatment and how they did once they had. The NIDA-funded X:BOT trial assigned 570 adults to monthly Vivitrol or daily buprenorphine-naloxone after inpatient detox and followed them for 24 weeks:
- Getting started: 72% of the Vivitrol group received the first injection, compared with 94% who started buprenorphine-naloxone.
- Everyone assigned: 65% on Vivitrol relapsed, compared with 57% on buprenorphine-naloxone. The authors tied most of that gap to people who relapsed early after never getting the first shot.
- Only people who started: relapse was 52% on Vivitrol and 56% on buprenorphine-naloxone, with no meaningful difference.
- Overdose: the study did not detect a difference in overdose events between the groups. There were only 5 fatal overdoses in total (2 on Vivitrol, 3 on buprenorphine-naloxone), so that is not proof the fatal risk is the same.
NIDA’s summary is that naltrexone can be as effective as buprenorphine when taken for a long period, but starting it is harder. The trial authors said agonist treatment should be encouraged for people who cannot complete detoxification. Keep the limits in mind: X:BOT was open-label, recruited from detox units, and is one trial. The Suboxone vs. methadone post covers the other options.
The Overdose Risk That Gets Skipped
After detox, tolerance to opioids drops. As the blockade fades, you can respond to lower doses than you used before, and the label says that can cause life-threatening overdose. It reports fatal overdoses in people who used opioids at the end of a dosing interval, after missing a dose, or after stopping treatment. The blockade can also be overcome. Taking large amounts of opioids to push through it is especially dangerous and can be fatal.
The label tells providers to discuss overdose reversal medicine such as naloxone at every injection, and to call 911 in any known or suspected overdose, even if naloxone is given. Families should know about this risk too.
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Side Effects and Safety Warnings
In the alcohol-dependence trials, 9% of people on Vivitrol stopped treatment because of a side effect, compared with 7% on placebo. These are common reactions at the 380 mg dose from those trials:
| Reaction | Vivitrol 380 mg | Placebo |
|---|---|---|
| Nausea | 33% | 11% |
| Any injection site reaction | 69% | 50% |
| Headache | 25% | 18% |
| Fatigue and related symptoms | 23% | 12% |
| Dizziness or fainting | 13% | 4% |
Rates can differ in people treated for opioid use disorder, so ask your prescriber what to expect. The label also lists serious warnings:
- Injection site reactions. Some are very severe, including cellulitis, abscess, and tissue death. Some needed surgery and some left significant scarring. Reported cases were mostly in women. Get swelling, a growing lump, or worsening pain checked.
- Liver problems. The label reports hepatitis and clinically significant liver dysfunction with Vivitrol. Seek medical attention for symptoms of hepatitis.
- Mood changes. People on Vivitrol should be watched for depression and suicidal thinking. In one alcohol trial of 624 people, depressed mood was reported by 10% on Vivitrol and 5% on placebo. If someone is in crisis, call or text 988.
- Lung and allergic reactions. The label warns about eosinophilic pneumonia (worsening shortness of breath needs medical attention) and serious allergic reactions, including anaphylaxis.
- Pain care and pregnancy. Tell every doctor, dentist, and ER team you get Vivitrol. Opioid pain medicines may be blocked or may not work as expected, and pain treatment may need specialist planning. Do not try to push through the blockade with extra opioids. For pregnancy, the label says the available data are not enough to identify a risk, so talk with your prescriber. SAMHSA says naltrexone is not a recommended option for anyone younger than 18.
Who May Be a Good Fit
- People who have finished opioid detox, are fully opioid-free, and want a medication that does not activate opioid receptors.
- People with alcohol use disorder who have stopped drinking before the first injection.
- People for whom a monthly shot suits better than a daily pill and who can make monthly appointments. These preferences may matter, but a prescriber still has to assess the indication, contraindications, opioid-free status, and other clinical risks.
The label lists these as contraindications, meaning Vivitrol should not be used: taking opioid pain medicine, current physical dependence on opioids, acute opioid withdrawal, a positive opioid urine screen or failed naloxone challenge, or a prior allergic reaction to it. A prescriber makes that call. Ask more questions first if you have liver disease, have a history of depression, or are pregnant. Treatment plans commonly include counseling and peer support, and may also address any co-occurring mental health conditions. Add a safety plan too: naloxone at home and a written relapse prevention plan. For more on treatment for opioid use, see the opioid addiction treatment page.
When to Reach Out for Help
Contact a prescriber or treatment team if you want to start Vivitrol but are still using opioids, if you missed your monthly shot, if you used opioids after your last one wore off, or if you notice severe injection site pain or swelling, symptoms of hepatitis, worsening shortness of breath, or signs of an allergic reaction. If you or someone close to you has low mood or thoughts of suicide, call or text 988. If you think someone is overdosing, give naloxone if you have it and call 911 right away.
Talking With a Professional
If Vivitrol is being considered for you or someone you love, the next step is a conversation with a qualified clinician. Questions worth bringing: How long do I need to be opioid-free, and how will that be checked? Should I start under medical supervision? Do I need liver tests? Where do I get naloxone? What happens if I miss a shot? The admissions team at Discovery Point Retreat can talk through what an assessment involves and what options exist. If you are weighing a more structured setting, the residential inpatient treatment page explains that level of care.
FAQ
Is Vivitrol addictive?
No. SAMHSA says naltrexone is not an opioid, is not addictive, and does not cause withdrawal when you stop. The danger after stopping is the lower opioid tolerance described above.
Can I get high or overdose if I use opioids on Vivitrol?
The blockade is designed to stop opioids from working, but large amounts can overcome it, and the label calls any attempt to do that especially dangerous. Overdose risk also rises near the end of the dosing interval, after a missed dose, or after stopping.
What if I miss my monthly shot?
The label says to get the next dose as soon as possible. The blockade fades toward the end of the month, so this is also a higher-risk window. If you used opioids in between, ask your prescriber whether you need another opioid-free period before the next shot.
Can I start Vivitrol if I am still drinking?
The label says patients should not be actively drinking at the first injection, and the alcohol trial’s benefit was clearest in people who had stopped drinking before their first dose. If you drink heavily, talk with a clinician before you stop, because alcohol withdrawal can be dangerous and Vivitrol does not treat it.
How is Vivitrol different from Suboxone?
Vivitrol only blocks opioid receptors. Buprenorphine, the medicine in Suboxone, works differently. In X:BOT, more people could start buprenorphine-naloxone (94% vs. 72%). Among those who did start either one, relapse rates were similar.
References
- Alkermes, Inc. VIVITROL (naltrexone for extended-release injectable suspension) prescribing information, label revised May 2026. DailyMed, National Library of Medicine. Accessed October 2026. dailymed.nlm.nih.gov
- Lee JD, Nunes EV, Novo P, et al. Comparative effectiveness of extended-release naltrexone versus buprenorphine-naloxone for opioid relapse prevention (X:BOT): a multicentre, open-label, randomised controlled trial. Lancet. 2018;391(10118):309-318. Accessed October 2026. pmc.ncbi.nlm.nih.gov
- National Institute on Drug Abuse. Medications for Opioid Use Disorder. Accessed October 2026. nida.nih.gov
- US Food and Drug Administration. Information about Medications for Opioid Use Disorder (MOUD). Accessed October 2026. fda.gov
- National Institute on Alcohol Abuse and Alcoholism. Treatment for Alcohol Problems: Finding and Getting Help. Accessed October 2026. niaaa.nih.gov
- Substance Abuse and Mental Health Services Administration. Naltrexone. Accessed October 2026. samhsa.gov
Related Reading
- Medically Assisted Treatment Program
- Suboxone vs. Methadone: Which Works Better for Recovery?
- Why MAT Nearly Doubles Your Chances of Recovery
- How to Create a Relapse Prevention Plan
Resources
- 988 Suicide and Crisis Lifeline. Call or text 988, or chat at 988lifeline.org. Free, confidential support 24/7.
- SAMHSA National Helpline. Call 1-800-662-HELP (4357) or visit the SAMHSA National Helpline page for free, confidential referrals to local treatment.
- 911. For any medical emergency, including suspected overdose, call 911 immediately.
This article is general education and is not medical advice.
If you or someone you love is weighing medication options for opioid or alcohol use disorder, call Discovery Point Retreat at (855) 245-7133 to talk with our admissions team.
