Stein MD, et al. - In view of the increasing risks for fatal overdose linked to fentanyl-adulterated heroin supply chains in the US, researchers investigated persons seeking treatment for heroin use (n = 239; 75.3% male, 81.2% White, 67% injectors) to determine the use of overdose risk reduction behaviors among them and if overdose risk reduction behaviors are correlated to perceptions about the presence of fentanyl in one's heroin. Participants figured that most heroin they use (69.2%) contains fentanyl, and nearly all participants (94.6%) were aware of the fact that fentanyl increases overdose risk. Use of none of the overdose reduction behaviors was reported in 15.5% of participants. Use of one or more behavior, at least “rarely,” was reported by most (84.5%). Frequency of individual overdose reduction behaviors was not found to be correlated with the beliefs about the presence of fentanyl in personal heroin supplies.