Does naloxone cause a positive urine opiate screen?

Ann Emerg Med. 1994 Dec;24(6):1151-3. doi: 10.1016/s0196-0644(94)70247-0.


Study objective: To determine whether the excreted metabolites of naloxone hydrochloride cause positive urine toxicologic screens for opiates.

Design: Prospective, randomized, double-blinded human protocol.

Setting: Urban Level I military emergency department.

Participants: Fourteen adult volunteers who took no routine medications, were not pregnant, had no known sensitivity to naloxone, and who were negative for a pretest urine and serum toxicologic screen.

Interventions: We administered either 2 or 4 mg IV naloxone to 14 subjects. Urine drug screening was obtained before administration and at 60 minutes, 6 hours, and 48 hours after administration.

Results: All urine drug screens using the enzyme-multiplied immunoassay technique were negative for opiates at both dosage levels. The sample size of 14 yielded a power of more than .99 to detect the difference between positive and negative samples.

Conclusion: Although the metabolites of naloxone hydrochloride are similar in structure to oxymorphone and are excreted in human urine for several days, naloxone was not associated with a positive enzymatic urine screen for opiates.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Double-Blind Method
  • Emergencies
  • Enzyme Multiplied Immunoassay Technique
  • False Positive Reactions
  • Humans
  • Middle Aged
  • Naloxone / chemistry
  • Naloxone / pharmacokinetics
  • Naloxone / urine*
  • Narcotics / urine*
  • Oxymorphone / chemistry
  • Oxymorphone / urine
  • Pilot Projects
  • Prospective Studies
  • Substance Abuse Detection / methods*


  • Narcotics
  • Naloxone
  • Oxymorphone