Can narcan (naloxone) cause a false positive on a drug screen test?

NO: According to an journal article by storrow in the archives of emergency medicine vol 24 issue 6 in 1995. When 14 volunteers had urine drugs screens done after IV naloxone, all urine samples were negative. But the only reason to get Naloxone is if you took too much narcotic. That orginial narcotic in your system likely would make the urine drug screen positive.

No, it does not.: “Does naloxone cause a positive urine opiate screen?” “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.” REF: https://www.ncbi.nlm.nih.gov/pubmed/7978599