KNOXVILLE, Tenn. — A powerful new synthetic opioid believed to be about 10 times more potent than fentanyl is being linked to a growing number of overdose deaths, raising concern among health and law enforcement officials.
In Knox County, Tennessee, cychlorphine has been tied to approximately 50 suspected overdose deaths this year, according to the Knox County Regional Forensic Center. The drug was first identified in the county just last fall.
Officials say the number of deaths connected to cychlorphine has climbed quickly in recent months. According to WBIR, when authorities first warned the public about the drug in February, it had been linked to 16 deaths. By April, that number had risen to about 40 across the region. It has since increased by at least another 10 suspected deaths.
“What’s especially troubling is that cychlorphine may have been circulating far longer than we know,” said Chris Thomas, chief administrative officer and director of the Knox County Regional Forensic Center, 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.”
The Knox County Regional Forensic Center was among the first in Tennessee to identify the drug, in part due to its advanced testing partnerships. While it was initially believed cychlorphine first appeared in the area in November 2025, the center says further analysis suggests it may have been present earlier.
National agencies have also sent out alerts about the substance. The U.S. Drug Enforcement Administration issued a warning about cychlorphine in March after it was detected in the Chicago area. Earlier this year, the Center for Forensic Science Research and Education also alerted the public about the opioid, which was first detected at the lab in mid-2024 but has been identified more frequently since mid-2025.
Authorities say many overdoses involving cychlorphine are still responding to naloxone and are urging the public to carry it, emphasizing that the illicit drug supply continues to evolve.
Emily’s Hope has partnered with several organizations to expand free access to naloxone in South Dakota and Kansas.
