New Opioids Called Nitazenes Are Emerging as Fentanyl Enforcement Intensifies

A class of synthetic opioids known as nitazenes is increasingly appearing in U.S. drug markets as enforcement against fentanyl ramps up, researchers and public-health laboratories say, raising concerns about a shifting and less predictable supply of lethal drugs.

Analogs of nitazenes have been detected in samples from at least 15 states, according to laboratory networks that analyze drug submissions from health departments, clinics and harm-reduction programs. Some nitazene compounds are reported to be roughly as potent as fentanyl, while a smaller number are exponentially stronger. The new synthetics are likely undercounted in official overdose statistics because many medical examiner and coroner offices do not routinely use the specialized testing needed to identify them.

The laboratory led by Nabarun Dasgupta at the University of North Carolina’s Gillings School of Global Public Health analyzes drug samples from more than 40 states and has identified nitazenes in 15. Protonitazene and metonitazene, two analogues similar in strength to fentanyl, have been most common on the East Coast; Dasgupta said Tennessee has shown among the highest concentrations in the nation. The Center for Forensic Science Research and Education’s early-warning system has also reported rising nitazene-related deaths.

Researchers said the nitazenes detected in North America appear concentrated in the United States and Canada more than in other regions. “In general, the United States and Canada really bear the majority of nitazene consumption around the world,” said Alex Krotulski, program manager for NPS Discovery, the center’s drug early-warning program. He and others warned that the country’s fragmented surveillance systems and delays in reporting make it difficult to obtain an accurate, timely national picture.

Current federal data systems, including the Centers for Disease Control and Prevention’s State Unintentional Drug Overdose Reporting System, categorize deaths from synthetic opioids broadly and do not always separate novel substances such as nitazenes from fentanyl or other opioids. That limitation, combined with the lack of uniform, advanced toxicology in many jurisdictions, means nitazene involvement in overdoses can go unrecognized.

Researchers and public-health experts say the growth of nitazenes may be related in part to intensified efforts to disrupt fentanyl trafficking. Officials point to recent policy actions, including the HALT Fentanyl Act signed into law in July, and stepped-up seizure and interdiction efforts that aim to reduce the flow of fentanyl into the United States. Some scientists described the situation through the lens of the so-called Iron Law of Prohibition: as enforcement tightens on a widely used drug, markets may move toward substances that are easier to transport and more potent by weight.

“We're at this really unique inflection point where a lot of the fentanyl supply is contracting,” Dasgupta said. He and other researchers caution that any transition away from fentanyl would probably be gradual. The volume of fentanyl currently in the U.S. drug supply remains large, and experts say it will likely continue to account for the majority of synthetic-opioid overdoses for the foreseeable future.

Joseph J. Palamar, a drug-use epidemiology professor at New York University and deputy director of the National Drug Early Warning System, said preliminary data show fentanyl has become harder to find, more expensive and, in some markets, less potent than before. "Fentanyl largely replaced heroin," Palamar said. "And I wonder, could nitazenes replace fentanyl?" He added that nitazenes frequently appear mixed with fentanyl or other substances, which complicates efforts to determine which compound caused an overdose.

Supply chains for fentanyl and nitazenes differ in important ways. Experts said most illicit fentanyl that reaches U.S. markets is trafficked through Mexico, whereas nitazenes are primarily synthesized in China and then distributed through different routes. While the two product streams sometimes overlap and can be mixed, they operate largely independently, making the dynamics of any market shift complex and regionally variable.

Sheila Vakharia, a national harm-reduction and policy expert, described the U.S. drug market as a patchwork of regional and urban supply chains that evolve at different rates. New substances typically appear first in a city or region, saturate local markets, and then spread to surrounding areas, she said. That pattern, along with inconsistent testing and reporting across jurisdictions, contributes to delayed recognition of new threats.

Public-health advocates warned that proposed federal budget cuts could further weaken the nation’s ability to detect and respond to emerging drugs. The Trump administration’s fiscal 2026 budget request listed the CDC’s National Center for Injury Prevention and Control — which houses SUDORS and other overdose surveillance activities — among programs to be eliminated, and proposed a $3.6 billion reduction in CDC funding. Congress has not finalized those cuts, but researchers said reductions in surveillance and laboratory capacity would hinder detection of novel synthetic opioids.

Health officials and researchers emphasized that the detection of nitazenes does not yet indicate a wholesale replacement of fentanyl. Rather, they said, the emergence of multiple analogues reflects a broader period of rapid change and diversification in the unregulated drug supply. The combination of shifting supply chains, limited testing capacity, and regional market differences makes forecasting future trends difficult.

Krotulski said he doubts the U.S. will ever have a fully accurate picture of drug emergence without coordinated, nationwide improvements in toxicology and data reporting. "I don't think there's ever going to be an accurate picture of what drug emergence looks like in the United States," he said.

Public-health officials urged expanded laboratory testing, increased real-time data sharing among jurisdictions, and sustained investment in surveillance as ways to improve detection of new substances and inform prevention and treatment efforts. For now, researchers and harm-reduction providers said the best immediate safeguards remain widespread access to naloxone for reversing opioid overdoses, drug-checking services where available, and outreach that warns people who use drugs about the potential for unpredictable mixtures and varying potencies in the illicit supply.

Dasgupta characterized the current moment as unlike previous transitions in the opioid market. "Fundamentally, an unregulated drug supply is going to always be changing," he said. "And we're just at kind of a period of hyper-change that we've never seen before."