Infrequent detection of unintentional fentanyl use via urinalysis among people who regularly inject opioids in Sydney and Melbourne, Australia.

There is limited evidence of unintentional fentanyl use among people in Sydney and Melbourne, Australia who regularly inject heroin, suggesting that, currently, there is very little illicit fentanyl in Australian drug markets accessed by supervised injecting facilities attendees. This study demonstrates the feasibility of quick onsite testing to cost-effectively screen large samples for fentanyl; however, the high false positive rate emphasises the need for confirmation of positive tests through advanced analytical techniques.