Seizures of pills containing fentanyl increased 834% between 2018-2021, putting many at risk for unintentional exposure and overdose

Graph of the number of pills containing fentanyl seized by law enforcement in the US, 2018-21
Credit: NIDA

Law enforcement seizures of drugs containing fentanyl—especially pills—are increasing in the United States, according to new research published in the journal Drug and Alcohol Dependence. The number of seized pills containing fentanyl has climbed dramatically: more than 2 million fentanyl-laced pills were confiscated in the last quarter of 2021, nearly 50 times the number seized in early 2018.

The findings suggest that a widening population of people who use drugs—including those who buy counterfeit pills of common drugs like benzodiazepines or painkillers—could be at risk for unintentional exposure to fentanyl.

Drug overdoses have surged to previously unseen levels, with overdose deaths in the United States topping 100,000 annually. Fentanyl, a synthetic opioid that is 30 to 50 times more potent than heroin, is a major driver of overdose deaths, as other drugs can be adulterated or contaminated with fentanyl and a lethal dose may be as small as two milligrams.

“Many people who use heroin already expect fentanyl to be in the drug supply and are aware of the dangers. But people who buy pills illegally on the ‘street’ that are said to be Xanax or oxycodone can overdose if such pills are laced with fentanyl, even trace amounts. This places a much wider population at risk that may not be expecting their drugs to be adulterated,” said Joseph Palamar, PhD, MPH, an associate professor of population health at NYU Grossman School of Medicine, an affiliated researcher with the Center for Drug Use and HIV/HCV Research (CDUHR) at NYU School of Global Public Health, and the study’s lead author.

National data on drug seizures and overdoses often lag and are reported a year or more later, hindering public health efforts to quickly address public health issues that arise. This research was conducted as part of the National Drug Early Warning System (NDEWS), which uses real-time surveillance to detect early signals of potential drug epidemics. NDEWS is led by a team of researchers at the University of Florida, NYU, and Florida Atlantic University, and is funded by the National Institute on Drug Abuse, part of the National Institutes of Health.

The NDEWS researchers examined data on law enforcement seizures of drugs from High Intensity Drug Trafficking Areas in the U.S. to determine the number of drug seizures containing fentanyl from January 2018 through December 2021. Drug seizures likely represent a small proportion of what drugs are being sold and consumed, experts say, so can be used as a proxy for drug availability.

The researchers found that pills now make up 29.2% of fentanyl seizures, with the number of seizures involving fentanyl-laced pills growing from 68 in the first quarter of 2018 to 635 in the last quarter of 2021 (an 834% increase). In the fourth quarter of 2021 alone, law enforcement seized 2,089,186 pills containing fentanyl, up from 42,202 pills seized in the first quarter of 2018 (a 4,850% increase, or nearly 50 times the number of pills).  

The researchers also found an increase in the number of law enforcement seizures of powders containing fentanyl (from 424 in the first quarter of 2018 to 1,539 in the last quarter of 2021, a 263% increase) and the total weight of powders seized (from 298 kg to 2,416 kg, a 710% increase over that same time period).

While the study did not capture what the pills were disguised as, nor what amount of fentanyl was found in them, given the risks of unintentional exposure to fentanyl, the researchers call for more education about the risks of buying pills without a prescription and about harm reduction approaches.

“People who buy illicit drugs can protect themselves by using test strips to test their drugs for fentanyl and should also carry naloxone, a nasal spray that can reverse overdoses,” said study author Daniel Ciccarone, MD, MPH, of the University of California, San Francisco.

The findings also highlight the importance of coordinated, real-time drug surveillance to shed light on new trends as they emerge.  

“Fentanyl-related deaths are continuing to increase in the United States, and there is a critical need for more real time data—especially regarding drug supply—to help with targeted prevention and harm reduction efforts,” added Linda B. Cottler, PhD, MPH, FACE, of the University of Florida, a study author and principal investigator of NDEWS. NDEWS reports the most up-to-date surveillance in Weekly Briefings.

Additional study authors include Caroline Rutherford and Katherine Keyes of Columbia University and Thomas Carr of the University of Baltimore’s Center for Drug Policy and Prevention and the Washington/Baltimore High Intensity Drug Trafficking Area Program. The research was supported by the National Institute on Drug Abuse (U01DA051126, R01DA044207, and R01DA054190).

The mission of the Center for Drug Use and HIV/HCV Research (CDUHR) is to end the HIV and HCV epidemics in drug using populations and their communities by conducting transdisciplinary research and disseminating its findings to inform programmatic, policy, and grass roots initiatives at the local, state, national, and global levels. CDUHR is a Core Center of Excellence funded by the National Institute on Drug Abuse (Grant #P30 DA011041).  It is the first center for the socio-behavioral study of substance use and HIV in the United States and is located at the NYU School of Global Public Health. For more information, visit

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