What Does MOP Mean on a Drug Test? (Opiates (morphine/codeine))?
Evidence-based answer reviewed against SAMHSA cutoffs and FDA assay documentation · Updated August 2026
Quick answer: MOP is the laboratory abbreviation for Opiates (morphine/codeine). MOP is the classic opiate slot at 2,000 ng/mL — morphine, codeine and heroin's 6-MAM marker land here.
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 Opiates
Urine: 2,000 ng/mL morphine/codeine initial; 2,000 confirm. Heroin's unique marker 6-MAM confirms at 10 ng/mL.
The federal opiate panel targets morphine and codeine at a deliberately high 2,000 ng/mL cutoff — set precisely so poppy-seed breakfasts don't trigger careers-ending positives — plus heroin-specific 6-MAM confirmation.
Detection windows
| Test type | Typical Opiates detection window |
|---|---|
| Urine | heavy: up to 4 days chronic |
| Saliva (Mouth Swab) | any: 1–2 days |
| Hair Follicles | up to 90 days |
| Blood | any: ~12–24 hours |
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)