A potent new synthetic opioid is spreading through the illicit drug supply, and federal officials are warning it’s harder to detect and harder to reverse than fentanyl alone. Cychlorphine has been linked to dozens of deaths since 2025, and it was named in a May DEA advisory on emerging synthetic drugs increasingly mixed into the nation’s fentanyl supply.
For behavioral health executives, the drug’s rise raises immediate questions about naloxone protocols, toxicology screening, surveillance tools like wastewater testing, and staff preparedness.
Here are 10 things to know.
1. Cychlorphine is an unregulated synthetic opioid not approved for human use. The DEA identified cychlorphine, alongside nitazenes, as one of a group of potent synthetic opioids increasingly turning up mixed into fentanyl and counterfeit pills, the agency said in its May 12 advisory.
2. It traces back to a 1960s Belgian research effort, not a modern illicit lab. Cychlorphine belongs to a class of compounds called orphines that were developed in a Belgian research lab in the 1960s in a search for stronger painkillers for conditions like bone cancer. The drugs were never approved for medical use because they were considered too strong and dangerous, The New York Times reported.
3. The recipe is publicly available, which is part of why it spread. Because the synthesis was published in academic journals decades ago and is now accessible online, people can produce the drug without the infrastructure needed for other illegal drugs, Keith Humphreys, a Stanford psychiatry professor and former senior drug policy adviser in the Obama administration, told the Times.
4. It may be up to 10 times as potent as fentanyl. Experts cited by the Times put cychlorphine’s potency at roughly 10 times that of fentanyl, a figure that aligns with the Office of National Drug Control Policy’s April drug threat notice, as reported by Becker’s.
5. Reversing an overdose may take multiple doses of naloxone — more than most people carry. The Times reported that cychlorphine can require numerous doses of Narcan to reverse, though most people carry only one or two doses at a time, consistent with DEA guidance that cychlorphine “might require several doses of naloxone to be effective.”
6. Standard fentanyl test strips don’t detect it. Test strips that can identify fentanyl are not effective at detecting cychlorphine, the Times reported, leaving both individual users and health systems with a blind spot that fentanyl-era tools weren’t built for.
7. Timing is critical for naloxone to work. Naloxone needs to be administered before brain swelling occurs, Lewis Nelson, MD, a medical toxicologist at Florida Atlantic University’s Charles E. Schmidt College of Medicine, told MedPage Today.
8. The drug has already spread beyond its initial hot spots. Cychlorphine has appeared in Europe and on the East Coast over the past couple of years, the Times reported, in addition to the Ohio, Tennessee and Texas cases Becker’s has covered and the San Francisco death examined by the Times.
9. Wastewater testing is being used — and re-funded — to catch novel drugs earlier. San Francisco had been testing wastewater to detect emerging substances until federal funding lapsed in 2024. It resumed the practice in July, with the city’s health department planning to begin publishing findings on novel drugs this fall, according to the Times.
10. At least 55 deaths nationally have been tied to the drug since 2025, with regional concentration in the South and Midwest. Cychlorphine has been linked to at least 55 deaths nationally from 2025 to 2026, with the highest prevalence in Ohio, Tennessee and Texas, MedPage Today reported Sept. 8. The Knox County (Tenn.) Regional Forensic Center reported 41 overdose deaths tied to the drug between July 2025 and February 2026.
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