A designer drug described as 10 times more potent thanfentanylis causing an uptick in U.S. overdoses, according to health officials in multiple states.
Known as cychlorphine, the synthetic opioid is relatively new, having first been identified overseas in 2024. A spate of overdose deaths in East Tennessee has been attributed to the drug, with the Knox County Regional Forensic Centersaying in a notice on Monday, April 6, that it has been linked to at least 41 deaths across 11 counties between July 2025 and February 2026.
"What’s especially troubling is that cychlorphine may have been circulating far longer than we know," Chris Thomas, chief administrative officer and director of the Knox County Regional Forensic Center, said in a statement. "And I’ve said this before – we don’t know if it’s contained to a limited supply or one bad batch, or if it’s representative of a longer-term shift in the drug supply. That’s what is really concerning."
"It has never been more dangerous to take street-level drugs than right now," he added.
Health officials in other states, includingFlorida,Kentucky,OklahomaandSouth Carolina, have also issued warnings amid the apparent proliferation of the drug, as toxicology data shows that roughly two dozen states have confirmed its presence locally.
The Center for Forensic Science Research and Education (CFSRE) likewiseissued a nationwide alertin January, saying cychlorphine is behind an "alarming" uptick in deaths both nationwide and globally.
Here's what ot know about N-Propionitrile chlorphine, also known as cychlorphine.
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What is cychlorphine (N-Propionitrile Chlorphine)?
N-Propionitrile chlorphine, also known as cychlorphine, is a synthetic or chemically manufactured opioid that global health officials began tracking in mid-2024. Like fentanyl, another highly potent synthetic opioid, it is used recreationally on its own or mixed with other drugs like heroin.
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It was firstdocumented by CFSREas a designer drug, or a substance that is engineered to mimic the effects of an established drug (like morphine, for example) while technically skirting legal regulations and established drug tests. It is part of an emergent subclass of synthetic opioids often called “orphines" or "orphine analogues," which are often distributed in powder or tablet form. Early reports have traced the drug's origins to China, according to the Knox County Regional Forensic Center, from which it likely spread to Europe and beyond.
Like other synthetic opioids, which are aleading cause of overdose death in the U.S., its potency means it can rapidly overwhelm the respiratory system in even very small doses, quickly rendering a person unconscious or unable to breathe.
Experts are still learning about cychlorphine and its effects. Its novelty means it is harder to detect – most toxicology tests administered by hospitals, first responders and law enforcement are not equipped to catch it,according to the Addiction Center. Its strength means that the drug used to reverse opioid overdoses, naloxone, more commonly known as Narcan, may not be as effective and may require several doses to work.
The CFSRE said in its January public alert that the U.S., Canada, Europe and Oceania have seen an "alarming increase in deaths" linked to synthetic opioids; cychlorphine, specifically, has been detected in a notably increased number of fatal drug overdoses since mid-2025.
Early data from testing on samples showed the drug to be approximately 10 times more potent than fentanyl, said CFSRE, though how accurately this translates to real-world use is still unknown.
Where in the US has cychlorphine been found?
Health officials are still developing tools and techniques to track the prevalence of newer orphines and other synthetic drugs. In January, the CFSRE had confirmed the presence of cychlorphine in New York, California, Illinois, Nevada, Pennsylvania, Tennessee and Texas.
Local and state governments inFlorida,Kentucky,OklahomaandSouth Carolinahave issued warnings alerting the public to the known presence of cychlorphine in the region.
The drug has likewise been detected in recent toxicology reports from Arkansas, Indiana, Maine, Maryland, Massachusetts, Missouri, New Hampshire, Ohio and West Virginia,according to Aegis Labs data.
This article originally appeared on USA TODAY:What is cychlorphine? Potent drug behind 'alarming' overdose deaths
