Study Suggests Decline in U.S. Opioid Overdose Deaths Linked to Changes in Fentanyl Supply

A supply shock in the illicit fentanyl market could underpin a downturn in U.S. overdose deaths that began in mid-2023, a new research paper has theorised, after an analysis that pulled in DEA reports on fentanyl purity and drug seizures as well as social media posts from drug users. 

Researchers pointed to a possible Chinese crackdown on manufacturers and traffickers of chemical precursors of fentanyl as a possible origin of this supply-side pressure.

What the study suggests

The study, published in Science, tries to understand why overdose deaths caused by synthetic opioids, after increasing 25-fold over 15 years and hitting a record 76,000 in 2023, suddenly declined in the summer of 2023. 

“In June, July of 2023, suddenly the curve turns down,” Peter Reuter, a criminology professor at the University of Maryland and co-author of the paper, told STAT News. “There was clearly some systematic event that drove it down over the next two years by at least one-third.” 

Theories about the downturn from public health experts have ranged from the success of drug treatment programs and harm reduction policies to a return to pre-pandemic patterns of drug use and the bleak possibility that the opioid crisis had already claimed the lives of the most vulnerable. But even combined, those demand-side pressures can’t explain a more than one-third fall in synthetic opioid overdose deaths, Reuter said.

“It has to be a supply-side shock,” he said, using an economics term for an event that suddenly reduces the availability of a commodity.

Has the reduction in fentanyl strength reduced overdose death rates?

To explore the possibility of a supply shock, Reuter and his fellow researchers compared overdose deaths to data on drug purity and seizures, reliable indicators of trends in the shadowy illicit drug market. 

Drawing on figures published by the Drug Enforcement Agency (DEA), they found that the average purity of fentanyl powder seized by U.S. law enforcement rose sharply in 2022, peaking at 25% by weight between January and May 2023, before falling sharply to around 11% by the end of 2024. 

In line with fentanyl purity trends, by the end of 2024 overdose deaths involving synthetic opioids had fallen by more than half from their May 2023 peak. Researchers also found a strong correlation between the purity of both fentanyl pills and powder and synthetic opioid overdose deaths between January 2019 and October 2024, in both peaks and troughs. 

Similarly, counts of fentanyl seizures—reported semi-annually by the National Forensic Laboratory Information System (NFLIS)—peaked in the first half of 2023, before falling by 15% in the second half of the year. By the second half of 2024, they were down 37% from their peak.

Against a backdrop of sustained public and political attention on the opioid crisis, this decline in seizures can’t be explained by a waning of enforcement but rather by restricted supply. Researchers also turned to more unconventional methods to track the supply-side pressure: social media posts by fentanyl users. They analysed Reddit posts about fentanyl shortages or “droughts,” as users often described them, on six subreddits from January 2021 to January 2025. 

They found a spike in posts about fentanyl shortages starting in July 2023, coinciding with the downturn in overdose deaths. Posts discussing the drought continued to rise throughout 2024, despite a moderator-imposed ban on them on one relevant subreddit. 

How drug trafficking affects the rates of overdose deaths in the U.S.

To track down this supply-side pressure, the researchers followed the trail of the fentanyl on U.S. streets: from Mexico, where it’s synthesised, to China, where precursor chemicals are manufactured and smuggled from. Any chokepoint here, from more aggressive U.S. border policing to conflict among Mexican drug cartels, could reduce the purity of fentanyl on U.S. streets and curb overdose deaths. To narrow down these pressures, researchers looked across another border and compared trends in fentanyl deaths in the U.S. to those in Canada.

Most Canadian fentanyl is synthesised from Chinese precursors but within Canada itself rather than in Mexico. If Canada saw a similar fall in overdose deaths, researchers would have to look at China rather than at the U.S. and Mexico. 

Canadian public health statistics confirmed that fentanyl overdose deaths fell there in tandem with the U.S. starting in the summer of 2023. What’s more, Canada also started reporting fewer emergency medical service responses to opioid poisonings and opioid-related hospitalisations at the same time. 

The study suggests that the origin of these parallel mortality downturns could be “actions by the government of China that resulted in greater scrutiny of production and export of precursor chemicals, including the removal of online advertisements and several marketplaces.” 

There’s precedent for Chinese crackdowns changing dynamics on North American street corners. In 2017, the Chinese government tightened regulatory control over carfentanil, a synthetic opioid around 100 times stronger than fentanyl. Seizures and deaths from carfentanil immediately fell in the Midwest, where it had previously been prevalent. 

The Chinese government, with characteristic opacity, hasn’t admitted to any campaign against fentanyl precursor producers. But the DEA isn’t so circumspect with its successes, and notably, it hasn’t claimed credit for the recent downturn in overdose deaths.

Overdose prevention and treatment

Reuter conceded that some of the decline in overdose deaths could still be attributed to demand-side factors such as increased access to Narcan and expanded access to medications used to treat opioid use disorder.

Even if supply-side factors drove most of the downturn, that doesn’t mean public policy should neglect those interventions. “The sensible policy by the U.S. government is treatment and prevention,” he said. 

This current fentanyl drought may not last. Trafficking organisations are likely to adapt to shortages of precursors over time, sourcing ingredients elsewhere and finding other workarounds, much as methamphetamine traffickers did when their access to precursors was limited.

They will have an incentive to adapt and maintain the illicit fentanyl market for as long as demand persists. So public policy must use the drought “as an opportunity to ramp up the prevention and treatment programs that have evidence of decreasing demand,” study authors conclude.