If you’ve been following the news out of Tennessee lately, you’ve probably seen the headlines about a drug called cychlorphine. They’re alarming, and for good reason. Since October 2025, this newly identified synthetic opioid has been linked to more than 30 overdose deaths across the state, with most of those deaths concentrated in East Tennessee counties, including Knox, Roane, McMinn, Campbell, Union, Anderson, Claiborne, and Sevier.
I believe that information saves lives. So, let’s talk about what cychlorphine is, what it does to the body, where it’s showing up, and what to do if you or someone you love needs help.
What Is Cychlorphine?
Cychlorphine, whose full scientific name is N-propionitrile chlorphine, is a synthetic opioid that belongs to a class of substances known as New Synthetic Opioids, or NSOs. These are lab-created compounds that are structurally different from fentanyl and its analogues but produce similar or more potent opioid effects.
The number that matters most: cychlorphine is estimated to be approximately 10 times more potent than fentanyl. To put that in perspective, fentanyl is already 50 to 100 times stronger than heroin. As Jim Joyner, president of the Ohio Association of Alcoholism and Drug Addiction Counselors, explained it to reporters, “you’re talking about very minute amounts of the drug that could be potentially lethal.”
This drug has never been approved for clinical use. It was not prescribed, diverted, or repurposed from a legitimate medical application. “This isn’t a drug that has been approved for clinical use, and it’s never been clinically approved to be sold on the market,” said Dr. Darinka Mileusnic-Polchan, chief medical examiner at Knox County Regional Forensic Center.
Where Did It Come From, and Where Is It Showing Up?
According to the Center for Forensic Science Research and Education (CFSRE), cychlorphine may have first appeared in China in 2024 before spreading to Europe, Canada, and the United States by mid-2025. That trajectory reflects the typical pattern for novel synthetic opioids: overseas synthesis, distribution through dark web channels, and detection in overdose deaths months or even years after the drug first circulated.
The DEA confirmed that cychlorphine was first reported in Florida by one of its laboratories in April 2024. Through the end of February 2026, DEA laboratories had identified the substance in 22 samples nationwide.
In Tennessee, the Knox County Regional Forensic Center first detected cychlorphine following a November 2025 overdose death in Roane County. Investigators later traced an earlier case in Knox County back to October 2025. By early 2026, the number of confirmed and suspected deaths in East Tennessee had reached 19, with the Tennessee Bureau of Investigation crime laboratory reporting 11 positive drug seizures in 2025 and nine more in just the first 30 days of 2026. The Tennessee Department of Health has since confirmed the statewide death toll exceeded 30 as of March 2026.
The drug is not staying in Tennessee. Cychlorphine has appeared in drug seizures in Chicago and California, prompted an overdose alert from the Gallia County Health Department in Ohio, and led the Kentucky Office of Homeland Security to issue a public safety warning after the drug was detected in central Kentucky. Internationally, cychlorphine has been identified in drug-checking programs in Toronto, confirmed through forensic analysis in France, and formally scheduled under Germany’s New Psychoactive Substances Act. Authorities in London have also linked it to fatal overdose investigations.
One of the most troubling parts of this story 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 the substance had been “showing up at an exponential rate” in toxicology reports, adding that officials don’t yet know whether this represents a single contaminated batch or a longer-term shift in the drug supply.
What Does Cychlorphine Do to the Body?
Cychlorphine acts on the same opioid receptors in the brain as heroin, fentanyl, and prescription painkillers. It produces intense euphoria, pain relief, sedation, and slowed breathing. Because of its extreme potency, a microscopic dose can be enough to cause a fatal overdose.
The Tennessee Department of Health says opioid overdoses, including those involving cychlorphine, can be suspected when a person’s breathing has stopped or severely slowed, they are unresponsive, or their fingernails and lips are blue or purple.
Additional signs include:
- Pinpoint (extremely small) pupils
- Limp body
- Gurgling or choking sounds
The danger is that these effects can come on faster than the person, or anyone nearby, can react. In the confirmed Tennessee deaths, most cases involved cychlorphine alongside other drugs, primarily methamphetamine and fentanyl, making recognition and response more complex. In at least one confirmed fatal case, however, cychlorphine was the only drug identified, with the substance measured at approximately 0.5 nanograms in femoral blood (a nanogram is one-billionth of a gram).
The Risks Are Different From Other Opioids
Several features of cychlorphine make it distinctly more dangerous than even the synthetic opioids that have dominated the overdose crisis for years.
You can’t see it or taste it: Like fentanyl before it, cychlorphine is odorless and colorless. People may be consuming it without any awareness that it’s in what they’ve purchased. Investigators believe the compound is being mixed with other drugs, including fentanyl and stimulants, meaning individuals may unknowingly consume a far stronger opioid than expected.
Standard drug tests don’t catch it: Many hospital, emergency, and even harm reduction drug-checking tools don’t detect cychlorphine because it has only recently emerged in the United States. Without expanded testing, it won’t appear in mortality data, which means deaths linked to it may be going unattributed. Current rapid test strips commonly used in community settings do not specifically detect cychlorphine.
Naloxone may require multiple doses: Naloxone (Narcan) does work against cychlorphine, but because of its extreme potency, a single dose may not be sufficient. “Naloxone is effective with cychlorphine, though it may require repeat dosing,” the Tennessee Department of Health confirmed.
Detection lags behind the drug supply: CDC officials have acknowledged that mortality data are not designed for early detection of emerging substances, because overdose investigations, toxicology testing, and death certifications all take time. By the time a compound appears in national mortality reporting, it has often already been flagged through product surveillance or laboratory identification programs.
How to Respond to a Suspected Overdose
If you believe someone is overdosing on an opioid, including cychlorphine, every second matters. The Tennessee Department of Health recommends the following steps:
Call 911 immediately. Do not wait to see if the person improves on their own.
- Administer naloxone (Narcan). Naloxone works against cychlorphine. Spray or inject it according to the product instructions.
- Provide rescue breaths. While naloxone takes effect, give rescue breaths. Supporting breathing is essential in the gap between administering naloxone and the person resuming normal breathing on their own.
- Repeat naloxone if needed. If breathing does not return or slows again, administer another dose. With a drug this potent, repeat dosing is expected.
- Stay until help arrives. Even if the person appears to recover, naloxone wears off faster than many opioids. They can re-overdose.
Where to get naloxone in Tennessee: you can obtain it through Regional Prevention Specialists with the Tennessee Department of Mental Health and Substance Abuse Services, or through your local health department.
Tennessee’s Good Samaritan Law provides legal protection for people who call 911 during an overdose. You will not face drug charges for seeking help.
How to Get Help for Yourself or Someone You Love
The emergence of cychlorphine is a reminder of something we’ve said for years at Holon Health: the illicit drug supply has never been more unpredictable or more dangerous. People who are using any substance, opioids, stimulants, pressed pills, are now at risk from compounds they cannot detect, cannot anticipate, and cannot dose safely.
If you or someone you love is struggling with opioid use, this is the moment to reach out. Treatment works. Medications like buprenorphine and methadone are highly effective at reducing opioid use and dramatically lowering the risk of overdose death. You do not have to wait until things get worse.
Here are some places to start:
- SAMHSA National Helpline: 1-800-662-4357, free, confidential, 24 hours a day, 7 days a week
- Tennessee Department of Mental Health and Substance Abuse Services: tn.gov/behavioral-health
- Crisis Text Line: Text HOME to 741741
- Holon Health: www.holonhealth.com
If you’re not ready to talk about treatment yet, please carry naloxone. Please tell someone you trust. Please don’t use alone.
References
1. Tennessee Lookout. (2026, March 2). *New synthetic opioid linked to 19 Tennessee deaths exposes limits in detection and legal clarity.* https://tennesseelookout.com/2026/03/02/new-synthetic-opioid-linked-to-19-tennessee-deaths-exposes-limits-in-detection-and-legal-clarity/
2. Rx and Illicit Drug Summit. (2026, March 12). *Emerging synthetic opioid “cychlorphine” linked to multiple overdose deaths in East Tennessee.* https://www.hmpglobalevents.com/article/emerging-synthetic-opioid-cychlorphine-linked-multiple-overdose-deaths-east-tennessee
3. Knox County Regional Forensic Center. (2026, February 5). *Preliminary tests: 16 deaths tied to new drug* [Media release]. https://www.knoxcounty.org/rfc/pdfs/mediarelease/2026/2026.02.05KnoxCountyRFCPreliminaryTests16DeathsTiedtoNewDrug.pdf
4. WSMV News. (2026, March 18). *Tennessee health officials say new drug has caused more than 30 overdose deaths across the state.* https://www.wsmv.com/2026/03/18/tennessee-health-officials-say-new-drug-has-caused-more-than-30-overdose-deaths-across-state/
5. The Hill. (2026, March). *What to know about cychlorphine, the synthetic opioid 10 times stronger than fentanyl.* https://thehill.com/policy/healthcare/5779927-potent-opioid-cychlorphine-alarm/
6. NWVCIL Blog. (2026, March 14). *New synthetic opioid 10 times stronger than fentanyl linked to 16 deaths in Tennessee.* https://nwvcil.org/blog/2026-03-14-cychlorphine-synthetic-opioid-tennessee-deaths
7. FOX17 News. (2026). *New synthetic opioid ‘cychlorphine’ linked to 16 overdose deaths across East Tennessee.* https://fox17.com/news/local/new-synthetic-opioid-cychlorphine-linked-to-16-overdose-deaths-across-east-tennessee-n-propionitrile-chlorphine-methamphetamine-and-fentanyl
8. WKYT. (2026, February 23). *Kentucky homeland security warns of new synthetic opioid detected in central Kentucky.* https://www.wkyt.com/2026/02/23/kentucky-homeland-security-warns-new-synthetic-opioid-detected-central-kentucky/
9. Governing. (2026, February 24). *Drug surveillance systems and the challenge of powerful new opioids.* https://www.governing.com/management-and-administration/drug-surveillance-systems-and-the-challenge-of-powerful-new-opioids
10. Action News Jax. (2026). *New synthetic opioid linked to 16 overdose deaths in East Tennessee.* https://www.actionnewsjax.com/news/trending/new-synthetic-opioid-linked-16-overdose-deaths-east-tennessee/FEKZHXO6HBEWDNL2BKX7MF6YYY/
11. FOX19 Cincinnati. (2026, February 23). *Cychlorphine drug advisory: Officials warn of synthetic opioid linked to overdose deaths.* https://www.fox19.com/2026/02/23/cychlorphine-drug-advisory-officials-warn-synthetic-opioid-linked-overdose-deaths/
12. News From the States. (2026). *New synthetic opioid linked to 19 Tennessee deaths exposes limits in detection and legal clarity.* https://www.newsfromthestates.com/article/new-synthetic-opioid-linked-19-tennessee-deaths-exposes-limits-detection-and-legal-clarity
13. Brooks Healing Center. (2026). *Cychlorphine and opioid analogs in Tennessee.* https://brookshealingcenter.com/blog/cychlorphine/
14. MedBound Times. (2026). *Cychlorphine: New synthetic opioid linked to overdose deaths detected across multiple U.S. states, health officials warn.* https://www.medboundtimes.com/usa/what-is-cychlorphine-new-opioid-detected-in-us-deaths
