Vivitrol is a once-monthly injection used to treat two conditions: alcohol dependence and opioid dependence. It contains naltrexone, a medication that blocks opioid receptors in the brain, reducing cravings and eliminating the rewarding effects of alcohol and opioid drugs. Unlike some other addiction medications, Vivitrol does not contain any opioid-like substances and carries no risk of physical dependence itself.
Two FDA-Approved Uses
Vivitrol is approved for alcohol dependence in people who can stop drinking before starting treatment. You cannot be actively drinking when you receive your first injection. The medication helps reduce the urge to drink by blocking the brain’s reward response to alcohol, making it easier to maintain sobriety over time.
The second approved use is preventing relapse to opioid dependence after detoxification. This means you must already be fully detoxed from opioids, including heroin, fentanyl, and prescription painkillers, before receiving Vivitrol. If opioids are still in your system when the injection is given, it can trigger sudden and severe withdrawal. Most providers require at least 7 to 14 days of being opioid-free before starting treatment.
In both cases, Vivitrol is meant to be part of a broader treatment plan that includes counseling or other forms of psychosocial support. The injection alone is not considered a complete treatment.
How Vivitrol Works in the Brain
Naltrexone, the active ingredient in Vivitrol, is an opioid antagonist. It attaches to opioid receptors (specifically the mu receptor, which is the primary target for drugs like heroin and oxycodone) and blocks them. When those receptors are occupied by naltrexone, opioids cannot bind and produce a high. If someone on Vivitrol uses an opioid, they will feel little to no effect from it.
This blocking action also affects alcohol cravings. Alcohol triggers the release of natural opioid-like chemicals in the brain called endorphins, which contribute to the pleasurable feeling of drinking. With naltrexone occupying those receptors, the endorphin reward signal is dampened. Drinking becomes less satisfying, which over time helps reduce the compulsion to drink.
How the Injection Is Given
Vivitrol is a 380 mg injection given once every four weeks into the gluteal muscle (the buttock). A healthcare professional must administer it, alternating sides with each monthly visit. It cannot be self-injected, given under the skin, or given intravenously. The extended-release formula means the medication slowly releases into your body over the full month, so there are no daily pills to remember.
How Vivitrol Differs From Suboxone
Vivitrol and Suboxone are both used for opioid dependence, but they work in fundamentally different ways. Suboxone contains buprenorphine, a partial opioid agonist that activates opioid receptors at a low level. This produces mild opioid-like effects, enough to ease cravings and prevent withdrawal without producing a strong high. Suboxone also contains naloxone, but that component only activates if someone tries to inject the medication, serving as an abuse deterrent.
Vivitrol takes the opposite approach. It blocks opioid receptors entirely and produces no opioid effects whatsoever. This means there is no physical dependence on Vivitrol and no withdrawal if you stop taking it. However, the tradeoff is that you must complete detox first, which can be a significant barrier for many people. Suboxone can be started while someone is still in mild withdrawal, making it easier to begin in many situations.
Both medications reduce cravings and help prevent relapse. The choice between them often comes down to practical factors: whether someone has completed detox, their treatment history, personal preference, and whether they want a monthly injection or a daily medication.
Side Effects to Be Aware Of
The most commonly reported side effects include nausea, headache, fatigue, and injection site reactions such as pain, hardness, or swelling at the injection site. Injection site reactions can occasionally be serious, leading to tissue damage if the injection is not placed correctly in the muscle. Any growing lump, intense pain, or darkened skin at the injection site should be evaluated promptly.
Vivitrol carries a warning about liver injury. While clinically significant liver damage is uncommon at the recommended dose, your provider will likely check liver function before starting treatment and periodically during it. Symptoms like unusual abdominal pain, dark urine, or yellowing of the eyes or skin warrant immediate attention.
The Overdose Risk After Stopping
One of the most important things to understand about Vivitrol is what happens after you stop taking it. While the medication is active, it lowers your tolerance to opioids. Your body adjusts to functioning without opioid stimulation for weeks or months. If you then return to using opioids at the same dose you used before treatment, you are at significantly higher risk of overdose because your body can no longer handle that amount.
Research from the Recovery Research Institute found that the incidence of overdose was roughly twice as high in the period immediately after stopping naltrexone compared to periods of no medication treatment at all. This does not mean Vivitrol causes overdose. It means that the reduced tolerance it creates becomes dangerous if someone relapses at their previous dose. This risk is highest in the first few weeks after a missed or final injection, when the blocking effect wears off but tolerance remains low.
For this reason, having a clear plan for what happens after Vivitrol is just as important as starting it. Ongoing counseling, support groups, and a strategy for managing cravings without the medication all reduce the likelihood of a dangerous relapse.