Research Identifies Restrictions on Fentanyl Precursor Chemicals as a Key Factor Behind the Downturn
After years of rising opioid overdose deaths, the United States began to see a sustained decline in mid-2023. A new study published in “Science” finds that this reversal was likely driven not by changes in domestic treatment or prevention efforts, but by a disruption in the global supply of illicit fentanyl.
The study is co-authored by University of Maryland School of Public Policy doctoral student Kasey Vangelov and Distinguished University Professor Peter Reuter, in collaboration with researchers from several universities and the United Nations. The findings emphasize how forces far beyond the U.S. health care system can shape life-and-death outcomes at home.
Co-authors include Keith Humphreys of Stanford University’s School of Medicine, Jonathan P. Caulkins of Carnegie Mellon University’s Heinz College, Harold Pollack of the University of Chicago’s Crown School of Social Work and Bryce Pardo of the United Nations Office on Drugs and Crime.
The research draws on several data sources to examine what changed in illicit opioid markets during this period. Taken together, the evidence shows that fentanyl became less available, most likely due to restrictions on precursor chemicals used in its production—an important factor behind the drop in overdose deaths.
“The study stitches together some very different data sources, which tell a fairly consistent story,” noted Vangelov. “Even if the fentanyl producers eventually find a new source of precursors outside of China, tens of thousands of individuals are alive today because of this disruption in the supply of fentanyl.”
Similar patterns outside the United States reinforce that conclusion. “Despite pursuing very different policies, Canada and the U.S. experienced strongly parallel fentanyl epidemics with respect to both the earlier rapid expansion and now also these unexpected but welcome declines in both deaths and the various indicators of supply,” said Caulkins.
The study shows that limiting access to the chemicals used to make fentanyl can interrupt production before the drug ever reaches the street. This approach is different from traditional enforcement, which often focuses on arrests or drug seizures after fentanyl is already circulating. The authors stress, however, that this does not mean supply-side enforcement alone is the solution to the overdose crisis. Treatment, prevention and harm-reduction efforts remain essential for achieving lasting declines in overdose deaths.
Humphreys underscored the public health implications. “Drug supply control is clearly essential for protecting public health,” he said.
The study also highlights the international scope of the U.S. overdose crisis. While U.S. drug policy has long focused on pressuring coca- and opium-producing countries, the fentanyl supply chain, which is rooted in synthetic drug production, presents a different set of policy challenges and opportunities. Precursor chemical controls are one area where international cooperation can have measurable effects, though the authors note that few countries have the regulatory capacity to enforce such measures at scale.
“It is important for policymakers to remember that supply as well as demand plays an important role in drug use and drug-related consequences,” Reuter said. “Sometimes events or interventions can disrupt supply by enough, and for long enough, to save lives.”
How long the decline will last remains uncertain. Past research on illegal drug markets has shown that producers often adjust quickly to new restrictions, and previous efforts to limit precursor chemicals have often produced only short-lived effects. What makes the current situation unusual is that the decline has already lasted longer than many experts would have expected, even though producers still have access to other chemicals and production methods.
The findings also emphasize how difficult it can be for policymakers to spot and address major changes in drug markets in real time. The authors note that weakening of federal drug monitoring systems has made it difficult to identify changes in supply and to respond before those shifts translate into harm.
Even as federal and state governments continue to invest in treatment and harm-reduction programs, the research draws attention to changes in the global drug supply, and to the limits of how well those changes are tracked. Understanding why overdose deaths started to fall, says the authors, will be important not just for keeping that progress going, but for being better prepared when drug markets shift again.
