Amount of naloxone used to reverse opioid overdoses outside of medical practice in a city with increasing illicitly manufactured fentanyl in illicit drug supply.

: Illicitly manufactured fentanyl (IMF) prevalence has increased. However, there is uncertainty about naloxone dose(s) used by nonmedical bystanders to reverse opioid overdoses in the context of increasing IMF. : We used community naloxone distribution program data about naloxone doses and fatal opioid overdoses from the Allegheny County Medical Examiner. From January 2013 to December 2016, staff interviewed participants who administered naloxone in response to 1072 overdoses. We calculated frequencies, percentages, and conducted a 1-way analysis of variance (ANOVA). : Despite increases in fentanyl-contributed deaths, there were no statistically significant differences between any of the 4 years (2013-2016) on average number of naloxone doses used by participants to reverse an overdose ( = 0.88; = .449). : Even though IMF is more potent than heroin and is a rapidly increasing contributor to drug overdose deaths in Allegheny County, the average dose of naloxone administered has not changed. Our findings differ from studies in different areas also experiencing increasing IMF prevalence. Additional investigations are needed to clarify the amount of naloxone needed to reverse opioid overdoses in the community caused by new synthetic opioids.