A newly emerging synthetic opioid is raising alarm among health officials and law enforcement across parts of the United States, as early reports link the drug to a growing number of fatal overdoses.
Cychlorphine, a powerful designer opioid, has been linked to at least 16 overdose deaths in eastern Tennessee, according to a February statement from the Knox County Regional Forensic Center.
The drug is believed to be up to 10 times more potent than fentanyl and may be resistant to standard overdose treatments, including naloxone, commonly known as Narcan.
“We’ve had probably four or five cases now where this was the only drug found in the system, and in very small quantities, it’s proving to be fatal,” Knox County Regional Forensic Center Director Chris Thomas told News Channel 11 last week.
Authorities in other parts of the country are also reporting signs of the drug’s spread. In a March 24 press release, the Marion County Sheriff’s Office warned that cychlorphine has been linked to a rising number of fatal overdoses in several states, including Illinois, Ohio and Kentucky.
The sheriff’s office said cychlorphine is often hidden in the illicit drug supply and may appear as an off-white, gray or tan powder, or in counterfeit pills designed to resemble prescription medications such as oxycodone or hydromorphone. Officials warned the substance is also commonly mixed into other drugs, including heroin, methamphetamine or “tranq” (xylazine), without the user’s knowledge.
Authorities said cychlorphine does not appear on standard toxicology screens or drug test strips, requiring specialized testing by federal agencies such as the Drug Enforcement Administration for confirmation.
“Due to the way this drug binds to the brain, a single dose of Narcan may not be enough to reverse an overdose. Multiple doses are often required to save a life,” the sheriff’s office added.
“We are in the direct pipeline between Chicago and Louisville, while not everything that happens in those places happens here, we should be aware of this potential threat. We are sharing this information now to ensure our citizens, hospitals, and first responders are prepared for this high-potency threat,” Sheriff Kerry Forestal said.
According to reports, Cychlorphine was first identified in parts of Europe in recent years before appearing in North America. By 2025, it had been detected in drug samples in Canada and the U.S.
Investigators believe the drug is being manufactured overseas, including in Russia and China, and trafficked into the United States through established smuggling routes.
Authorities continue to monitor its spread, warning that cychlorphine may be only the latest in a series of increasingly potent synthetic opioids entering the illicit drug market.
