McMaster University

Michael G. DeGroote
National Pain Centre

Scope of Search

Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain

Appendix B-3: Urine Drug Screening (UDS)

Table B Appendix 3.1 Immunoassay versus Chromatography for Detection of Opioid Use



Does not differentiate between various opioids Differentiates: codeine, morphine, oxycodone, hydrocodone, hydromorphone, heroin (monoacetylmorphine).
Will show false positives: Poppy seeds, quinolone antibiotics. Does not react to poppy seeds.
Often misses semi-synthetic and synthetic opioids, e.g., oxycodone, methadone, fentanyl. More accurate for semi-synthetic and synthetic opioids.

Table B Appendix 3.2 Detection Times for Immunoassay and Chromatography

Drug Number of days drug is detectable
Immunoassay Chromatography
Benzodiazepines (regular use)
  • 20+ days for regular diazepam use.
  • Immunoassay does not distinguish different benzodiazepines.
  • Intermediate-acting benzodiazepines such as clonazepam are often undetected.
Not usually used for benzodiazepines.
Cannabis 20+ Not used for cannabis.
Cocaine + metabolite 3–7 1–2
Codeine 2–5 1–2 (Codeine metabolized to morphine.)
Hydrocodone 2–5 1–2
Hydromorphone 2–5 1–2
Meperidine 1 (often missed) 1
Morphine 2–5 1–2: Morphine can be metabolized to hydromorphone
Oxycodone Often missed 1–2

— Source: Adapted from Brands 1998