Quick answer
Naltrexone is typically detectable in urine for 1–3 days (oral); injectable releases for weeks after any use. It is not part of standard employment panels.
Not screened on standard employment panels.
Typical cutoff: Never screened on standard panels; specialized adherence monitoring exists in treatment programs.
Detection window by test type
| urine | |
|---|---|
| Any use | 1–3 days (oral); injectable releases for weeks |
| saliva | |
| Any use | ~1 day |
| hair | |
| Any use | rare |
| blood | |
| Any use | ~1 day |
Ranges reflect typical published detection windows and vary with dose, frequency, body composition, hydration and the assay used.
Key details
Naltrexone blocks opioid receptors rather than activating them — it's the opposite of an opioid in screening terms and appears nowhere on employment panels. Treatment programs may monitor levels to verify adherence to monthly injections.
Frequently asked questions
How long does naltrexone stay in your system?
In urine, typical detection is 1–3 days (oral); injectable releases for weeks (any use). Hair can detect use for up to 90 days and saliva/blood windows are usually shorter.
Will naltrexone show up on a standard drug test?
No — Naltrexone is not part of the standard 5-, 10- or 12-panel or DOT tests. It would require a specialised or expanded assay.
How accurate are these detection windows?
They are typical ranges from published literature and assay documentation, not guarantees. Clearance depends on dose, frequency, metabolism and the specific test cutoff used.
Related substances
Cite this page
DrugPanels. “Naltrexone Detection Time.” https://drugpanels.com/detection/naltrexone/. Accessed 2026-09-10.
Sources
- SAMHSA drug testing resources and analyte specifications — Substance Abuse and Mental Health Services Administration — samhsa.gov
Detection windows describe typical ranges from the published literature and assay documentation; individual results vary. See our methodology.