Vivitrol is the brand name for a long-acting injectable form of naltrexone, given once a month. It is used for opioid use disorder and alcohol use disorder. A single injection replaces a daily pill, so staying on the medication becomes a scheduled appointment rather than a decision someone makes every morning.
How Vivitrol Works
Naltrexone is an opioid antagonist. It blocks the brain’s opioid receptors. That makes opioids unable to produce a high, and it dulls the reward and craving that drinking triggers. Injected into muscle, the drug forms a small depot that releases slowly over about 28 days, so the blockade holds steady through the month. Cravings often ease. With the high off the table, one of the strongest pulls back toward use loses its force, and the monthly visit gives the care team a regular look at how someone is doing.
Protection fades near the end of each cycle, which is why a missed injection matters. If an appointment slips, call the provider and reschedule right away. A few days late is usually manageable, but a longer gap leaves the receptors open and raises the risk of a lapse.
What Is Required Before Starting Vivitrol
The patient has to be fully opioid-free first, which usually means completing a medically supervised detox. Starting too early triggers precipitated withdrawal: a sudden, severe reaction that is far worse than withdrawal left to run its natural course. Doctors confirm readiness with a physical exam and sometimes a naloxone challenge test. Screening also checks liver function and other conditions that would rule the medication out. Moving from methadone or buprenorphine to Vivitrol takes especially careful timing.
Two facts deserve emphasis before the first shot. Vivitrol blocks opioid pain medication, so anyone living with chronic pain needs a non-opioid plan worked out in advance, and every treating clinician, emergency staff included, should be told about the injection. Tolerance also drops during treatment, so a return to opioid use carries a higher overdose risk than it did before.
