How long is required to be opioid-free before starting Vivitrol (naltrexone)?
To start Vivitrol (extended-release naltrexone) safely, you must have been completely opioid-free long enough to avoid precipitated opioid withdrawal once naltrexone begins blocking opioid receptors. The standard requirement is:
- At least 7 to 14 days since your last use of short-acting opioids (for most patients, 7 days is commonly used, and longer can be required depending on the situation).
- At least 10 to 14 days after long-acting opioids or opioid medications with longer-lasting effects.
- For people using methadone, the opioid-free interval is typically longer, often 10 to 14 days.
The exact interval can vary based on which opioid you used, your dose, and how you were taking it. Clinicians often confirm opioid-free status using symptoms and sometimes a urine drug test before giving Vivitrol.
What counts as “opioid-free” before Vivitrol?
Being opioid-free means no exposure to opioids before the injection, including both prescription and illicit opioids. Common examples include:
- Heroin and other short-acting opioids
- Oxycodone, hydrocodone, morphine, hydromorphone, fentanyl (even if patch-based)
- Methadone and other long-acting opioids used for maintenance or pain
Even if you take opioids less frequently, you still need the full opioid-free window for your specific opioid so naltrexone does not trigger withdrawal.
What happens if you start Vivitrol too soon?
Starting naltrexone (including Vivitrol) while opioids are still active in your body can trigger sudden, uncomfortable, or severe withdrawal symptoms. This is why clinicians require a defined opioid-free period before the first injection.
Where do you confirm the rule for your case?
For precise timing instructions tied to your opioid exposure history (for example, methadone vs. short-acting opioids), your prescriber will use the Vivitrol prescribing information and clinical guidance. If you want, tell me which opioid (and whether it was short-acting, long-acting, or methadone) and when your last dose was, and I can help you interpret the typical opioid-free window.