Although increased heroin use and risk taking likely contribute, available data suggest contamination of the heroin supply with illicitly manufactured fentanyl as the overwhelming driver of the recent increases in opioid-related overdose deaths. Illicitly manufactured fentanyl is usually added to or sold as heroin. For every individual using heroin during recent years in the United States, it is likely that the risk of overdose death has increased considerably.
Fentanyl is approximately 50 times as potent as heroin. This provides strong economic incentives for drug dealers to mix fentanyl with heroin and other drugs because smaller volumes can provide equally powerful effects with lower costs and easier transport. Many people who use heroin are not seeking fentanyl and try to avoid it.3 It can be difficult to identify fentanyl, particularly in the white powder heroin typically sold in states east of the Mississippi River.4 The black tar and brown powder heroin typically sold in Western states might be limiting the penetration of fentanyl into this market for now. Among jurisdictions reporting provisional 2016 data, increases in drug overdose deaths since 2015 were much greater east of the Mississippi River.2