WASHINGTON — A powerful synthetic opioid estimated to be 10 times stronger than fentanyl has been surfacing in multiple states, contributing to overdose deaths.
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Cychlorphine has been linked to a growing number of fatal overdoses in several states. In one Tennessee county, the drug has been linked to 50 suspected overdose deaths in the last year, according to Knox County officials. The number of suspected overdose deaths linked to cychlorphine has risen rapidly in recent months.
When Knox County officials first publicly warned about the drug in February, it had been associated with 16 deaths. By April, the Knox County District Attorney General’s Office reported roughly 40 deaths across the region tied to the opioid. That figure has since increased by at least another 10 suspected fatalities.
Health and law enforcement officials across multiple states have been sounding alarms about newer drugs that were increasingly detected in 2025.
Alex Krotulski is director of the Center for Forensic Science Research and Education, a federally funded toxicology lab in Horsham, Pennsylvania, that is an important part of a national illicit drug early warning system.
In all of last year, the lab identified 27 new drugs. Less than five months into 2026, the lab already has identified 23, he said.
What is cychlorphine?
Among the drugs on the lab’s radar is cychlorphine, a potent synthetic opioid described as up to 10 times stronger than fentanyl. Experts say it is being used as a cutting agent, added to other illicit drugs, without the buyer’s knowledge.
Cychlorphine can appear in multiple forms, including powder and pills, and may also exist in liquid form due to its chemical properties.
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“The drug supply continues to change and evolve,” Krotulski said.
Experts warn that these newer drugs can be more difficult to detect with standard testing methods.
“Fentanyl test strips don’t detect anything that’s not fentanyl,” Dr. Rachel Wirginis, an addiction medicine specialist at Oklahoma State University said.
She added that people may unknowingly consume these substances, particularly when drugs are obtained outside of a pharmacy.
Back in April, a South Carolina coroner said they discovered the drug during an investigation into a woman’s death that initially did not show signs of drug use in standard toxicology testing. Richland County Coroner Naida Rutherford said they were the only agency in South Carolina to have a positive result for cychlorphine so far.
In May, Arkansas officials confirmed the state’s first overdose death linked to cychlorphine.
Officials also warn that overdoses involving cychlorphine may require multiple doses of naloxone, commonly known as Narcan, to reverse.
“Maybe one spray of naloxone or Narcan is not enough. And so that’s something that we can expect to see with cychlorphine too,” Wirginis said.
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