What Does BZO Mean on a Drug Test? (Benzodiazepines)?
Evidence-based answer reviewed against SAMHSA cutoffs and FDA assay documentation · Updated August 2026
Quick answer: BZO is the laboratory abbreviation for Benzodiazepines. BZO flags alprazolam/diazepam/clonazepam class (~300/200 ng/mL). Not on basic 5-panels.
Reading your cup or lab report
Multi-panel cups print 2–4 letter codes beside each strip line. One line per drug class; a visible control line plus absent drug line = negative for that class. Faint lines still count as present (they're competitive-inhibition assays) — the classic misread.
About Benzos
Expanded-panel urine screens commonly at 300 ng/mL (oxazepam equivalent) with 200 ng/mL confirmation.
Benzos are not on the basic federal 5-panel, but they are included on most 10- and 12-panel employment screens. Whether your job tests for them depends entirely on panel size and employer policy.
Detection windows
| Test type | Typical Benzos detection window |
|---|---|
| Urine | short_acting: alprazolam/lorazepam: ~2–4 days; long_acting: diazepam/clonazepam: up to 10 days; weeks in long-term heavy users (nordiazepam accumulates) |
| Saliva (Mouth Swab) | any: 1–3 days |
| Hair Follicles | up to 90 days |
| Blood | any: 1–2 days |
Related codes on the same cup
Cups group codes logically: AMP/mAMP (stimulants), OPI/MOP/OXY/BUP (opioid family), BZO/BAR (depressants), COC/THC/PCP (classics), plus validity markers like creatinine printed on lab reports rather than cups.
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Do prescriptions count against me?
No — verified prescriptions report as negative through the Medical Review Officer. Declare medications at collection and answer the follow-up call.
Sources & further reading
- SAMHSA — Mandatory Guidelines for Federal Workplace Drug Testing Programs (cutoffs, MRO process)
- DOT — 49 CFR Part 40 procedures for transportation workplace testing
- Brahm NC et al., Mayo Clinic Proceedings 2008;83(1):66–76 — false-positive cross-reactivity reference
- FDA — drug-of-abuse test device labeling (detection window conventions)