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By Giulia Carbonaro
Senior Reporter
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Dozens of deaths linked to a new potent synthetic opioid, cychlorphine, have been reported across the country over the past year, including a 16-year-old in San Francisco whose autopsy revealed the presence of the dangerous drug.
Dante Paul Lacourte was found overdosing in his bed by his mother on April 7, in the affluent neighborhood of Lower Nob Hill. His was the first cychlorphine-related death in San Francisco, marking the arrival of the drug in the city of over 800,000 residents, which is still reeling from the devastation caused by the fentanyl epidemic.
Some two weeks later, health officials in the city were warning residents of the dangers of the new “powerful non-fentanyl synthetic opioids” circulating in the city in the guise of counterfeit pills.
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The street drug, whose emergence over the last couple of years has got public health officials in the U.S. and across the world alarmed, might be beckoning a new wave of the nation’s opioid crisis, according to experts, as fentanyl loses its dominance on the market.
At least 55 deaths nationwide have been linked to the drugs between 2025 and early 2026, according to a drug threat notice issued by the Office of National Drug Control Policy (ONDCP) in April. Since then, the number has likely gone up.
The Knox County Regional Forensic Center (KCRFC) in Tennessee reported that cychlorphine was linked to 41 overdose deaths in the state between July 2025 and February 2026. The number of cychlorphine-related deaths in the state has since then increased, officials said.
What Is Cychlorphine?
Cychlorphine, or N-propionitrile chlorphine, is a laboratory-made drug which belongs to a class of synthetic opioids known as “orphines” or benzimidazol-2-ones.
It is structurally similar to other benzimidazolones, such as brorphine, spirochlorphine and chlorphine, with the key difference that cychlorphine extends the chlorphine structure by adding a propionitrile group to the benzimidazole nitrogen. It is not, according to experts, a fentanyl analog.
Across the U.S., cychlorphine has been found primarily in powders, tablets, and counterfeit pills. According to the ONDCP, it has been found mixed in with fentanyl or drugs such as methamphetamine, bromazolam, cocaine, and others, as well as on its own.
Where Is Cychlorphine Coming From?
Cychlorphine is not technically a new drug. It was first synthesized and studied in the 1960s in a Belgian lab, when researchers thought orphines could be used as pain relievers; but they were never marketed or approved for medical use.
The drug that got physicians and health officials on high alert now, cychlorphine, originated in China in 2024, moved to Europe, and reached U.S. streets later that year, according to officials. Its presence in the U.S. seemed to have increased after China placed restrictions on nitazenes in July 2025, showing how quickly traffickers have shifted to an alternative product.
How Does It Compare to Fentanyl?
A cychlorphine-induced overdose may look a lot like fentanyl, heroin or prescription-opioid poisoning, though it is chemically distinct from these substances.
At the moment, as fentanyl remains deeply ingrained in the North American illegal opioid supply, cychlorphine often appears mixed into fentanyl products rather than sold as a clearly identified alternative, according to Phoenix Rising Recovery.
But cychlorphine can be particularly dangerous because it is not expected to react with fentanyl or nitazene test strips, which means that an unregulated pill or powder can test negative for these substances while still containing a very potent opioid. Routine hospital opioid urine screens may also miss it.
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Crucially, these man-made drugs, orphines, are considered to be much more potent than an opioid like fentanyl. In the case of cychlorphine, experts have estimated it to be up to 10 times stronger than fentanyl.
But there is still a lot we do not know about the new drug, as Jon E. Sprague, PhD, of Bowling Green State University in Ohio, highlighted, telling MedPage Today: “What’s the human potency? We don’t know. How long does it last? We don’t know.
“How is it metabolized? We don’t know. How well does it cross into the brain? We don't know.”
Where in the US Has It Been Detected?
The Drug Enforcement Administration (DEA) reported its first U.S. cychlorphine detection in Florida in April 2024; within a couple of years, it has moved from the East Coast to the West Coast, with detections quickly multiplying.
In 2025, according to ONDCP, cychlorphine was detected in 106 instances in 10 states across all four U.S. regions. Detections were most concentrated in the South, Midwest, and Northeast regions, according to officials.
Cychlorphine-related deaths, in particular, have hit East Tennessee particularly hard.
KCRFC first discovered the drug in the state in late November 2025, when the substance appeared in a Roane County overdose death. Officials later identified an earlier case in Knox County dating back to October 2025.
In a February update, KCRFC reported 16 deaths tied to the new drug. In April, officials in the county revised the total death toll to 41 between July 2025 and February 2026.
Chris Thomas, the center’s chief administrative officer, told MedPage Today that cychlorphine-related deaths in Tennessee have now reached 58 deaths.
“It has never been more dangerous to take street-level drugs than right now,” Thomas said in a statement.
It is complicated to get the full picture of how cychlorphine is hitting the U.S. The counts of cychlorphine-related deaths available from officials so far come from different reporting systems, time periods, and case definitions. Some cychlorphine-related deaths may have gone unreported, testing is not uniform across states, and the presence of other drugs like fentanyl, methamphetamine or cocaine might be making identifying the new drug harder.
What seems clear, however, is that the drug seems to have claimed more victims and moved across state lines since the latest ONDCP update. In July, Dr. Alex Krotulski, the director of toxicology and chemistry at the Center for Forensic Science Research and Education (CFSRE), told SciLine that cychlorphine-related deaths had reached a total of 140 across nearly 20 U.S. states and Canada.
Talking to SciLine, Krotulski acknowledged the challenges of tracking the spread of the new drug.
“So each sort of region, every public health department and health department in different states, is kind of doing their own part. There’s been a lot of great, again, communication about the substance and about the fact that the substance exists,” he said. “Again, it’s just a challenge of knowing exactly when it’s going to pop up and where it’s gonna pop up. And that’s something that the public health departments really have to track through drug testing. And again, many are doing that very well, but again, just really never know when it is going to pop up.”
Newsweek contacted ONDCP, KCRFC, UNODC and CFSRE for comment by email on Tuesday.
What About the Rest of the World?
The United Nations Office on Drugs and Crime (UNODC) reported in May that cychlorphine had been identified in 10 countries, 182 drug seizures and 78 cychlorphine-related postmortem cases.
The drug has also been detected in Europe, with the European Union Drug Agency reporting that five European Union member states reported five cases of acute non-fatal poisoning and 18 deaths with confirmed exposure to orphines, mostly cychlorphine, between June 2024 and January 2026.
Detection of the drug has been confirmed in France and Germany.
What Happens Next?
It is certainly concerning that cychlorphine has reached the West Coast and San Francisco, an area that has been ravaged by the fentanyl crisis over the past decade. In 2021, then-Mayor London Breed declared an official state of emergency in the Tenderloin neighborhood, where most of San Francisco’s overdose deaths occurred.
The authorities are wary of the potential for a new wave of deadly synthetic opioids. San Francisco Mayor Daniel Lurie wrote about Lacourte’s death on Monday, saying on social media that the “tragic case set off a sweeping investigation, which led SFPD to arrest four people while seizing more than 20,000 counterfeit pills, along with fentanyl and multiple firearms.”
“In the past, San Francisco was caught flat-footed when fentanyl hit our streets. My administration will not let that happen again,” Lurie said.
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The mayor warned the public that the new drug might be present in counterfeit pills sold on social media as Xanax, Adderall, or oxycodone, though they can contain fentanyl or other powerful synthetic opioids.
“If you suspect an overdose, give naloxone immediately and call 911. When given in a timely manner, naloxone—also known as Narcan—is effective against these new opioids,” Lurie wrote.
Newsweek contacted the San Francisco Department of Public Health and Lurie’s office for comment by email on Tuesday.
At the national level, more than 400,000 Americans have died from fentanyl-related overdoses since the fentanyl crisis began. Annual deaths have declined significantly since peaking in the early 2020s, but an explosion of cychlorphine across the country could threaten the results achieved in curbing the opioid crisis.
Contact Newsweek editors on this story: Tobias Meyjes and Emma Lee-Sang
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