Cychlorphine Is Spreading Nationwide — and Fentanyl Test Strips Often Won't Detect It

Ohio health officials issued a statewide warning this week about cychlorphine, a synthetic opioid that is up to four to ten times more potent than fentanyl and, because of its chemistry, is often invisible to the fentanyl test strips many people now rely on.

The warning is not about a single bad batch. Cychlorphine was first identified in Ohio in July 2026 and has been detected sporadically since, and over the past month it has surfaced in Louisiana, Missouri, Texas, Arizona, Rhode Island, and California — including in counterfeit pills that looked identical to prescription medications and in at least one college community where two students died in separate incidents. Federal and state agencies have been tracking the compound since early 2026, when the Center for Forensic Science Research and Education (CFSRE) linked it to more than two dozen fatal overdoses in the United States and Canada.

This alert explains what cychlorphine is, why standard harm-reduction tools do not reliably catch it, what to do if you or someone you love may be exposed, and where to get help.

What happened

On September 28, health officials across Ohio warned that cychlorphine — sometimes spelled "cyclorphine" in local reporting — has been found in the state's drug supply and can linger in the body for days. Their advisory highlighted three clinical points:

• Potency. Cychlorphine is roughly four to ten times more potent than fentanyl by weight. That means a dose visually indistinguishable from what someone normally uses can be far more dangerous.
• Test strip blind spot. Typical fentanyl test strips are designed to detect fentanyl and a limited set of closely related compounds. Cychlorphine frequently returns a negative result on those strips.
• Naloxone response. Overdoses involving cychlorphine may require more doses of naloxone than a typical opioid overdose, and breathing may need to be supported manually until help arrives.

Within the same week, the DEA's Rocky Mountain Division issued its own warning about the drug, Louisiana officials connected cychlorphine to overdose deaths in their state, emergency responders in Austin described a pattern of naloxone-resistant overdoses that could be consistent with the drug, and Missouri officials stressed that fentanyl test strips would not find it. Campus health and public safety offices warned students at several universities in the South and Midwest.

What cychlorphine is

Cychlorphine (N-propionitrile chlorphine) belongs to a family of synthetic opioids called benzimidazolones. It is not fentanyl and not a fentanyl analog — it is an entirely different chemical structure that happens to act on the same receptors in the brain. That distinction matters for two practical reasons:

1. Detection. Because its structure differs, immunoassay-based fentanyl strips can miss it. A "clean" strip result is not proof that a substance is free of ultra-potent opioids.
2. Expectations. Potency estimates made for fentanyl do not transfer. People who have developed tolerance to fentanyl may still be at elevated risk.

Cychlorphine has been appearing in counterfeit pills sold as common prescription medications and in powder sold as fentanyl or other opioids. In Mississippi, two University of Mississippi students were found dead in separate incidents in late September 2026; kratom products were present at both scenes, and investigators have cautioned that the causes of death have not been determined. Officials have nonetheless warned students to avoid unregulated kratom and "7-OH" products sold at smoke shops and online, because unregulated products have been found to contain other compounds than what their labels claim.

Clinical consequences

1. Overdose can look the same — and behave differently. Cychlorphine overdoses present with the classic picture: slow or stopped breathing, blue or gray lips and fingertips, limp body, unresponsiveness. The difference is what happens after naloxone. Because of the drug's potency and receptor behavior, one dose may not be enough. Current guidance is unchanged in principle: give naloxone, call 911, support breathing, and give additional doses if there is no response.

2. Duration matters. Ohio officials note the drug can persist in the body for days. Practically, that means someone who is revived after an overdose needs supervision afterward, since re-sedation is possible once naloxone wears off. It is not a "reversed and done" situation.

3. Withdrawal can be severe. The rise of ultra-potent synthetic opioids has produced harder withdrawal syndromes nationally, with more intense symptoms and, for some patients, longer tapers. Anyone with physical dependence on opioids — including fentanyl — should not attempt abrupt self-detox from an unknown supply. Medically supervised withdrawal and medications for opioid use disorder (buprenorphine, methadone, or extended-release naltrexone) remain the evidence-based routes, and they work regardless of which synthetic opioid is in the supply.

4. Tolerance does not equal protection. People with high fentanyl tolerance still die from cychlorphine, because dosing is unpredictable and the compound is not interchangeable.

What to do

If you use drugs:

• Do not use alone. If you do use alone, tell someone and set a check-in; never lock the door.
• Start lower than usual when the supply changes hands or the source is new — and give any dose time to take effect.
• Carry naloxone. Two or more doses is better than one. Free naloxone is available from many health departments, harm-reduction organizations, and pharmacies.
• Treat a negative fentanyl strip as incomplete information. A strip can tell you fentanyl was detected; a negative result does not rule out cychlorphine, nitazenes, medetomidine, or other adulterants. Drug-checking services that use laboratory instrumentation are more informative where available.
• Be careful with non-pharmacy pills and unregulated herbal products sold as kratom or "7-OH." If it did not come from a pharmacy with a prescription, its contents are not guaranteed.

If you are a family member or friend:

• Learn the overdose response sequence now, before you need it: call 911 → give naloxone → support breathing → stay → give another dose if there is no response in two to three minutes.
• Keep naloxone where you can reach it in seconds, not in a drawer you have to search.
• Know your state's Good Samaritan law. In most states, calling 911 for an overdose gives the caller and the person overdosing limited protection from drug possession charges. Fear of arrest is what keeps people from calling.
• Talk about the supply, not just the behavior. Warnings land better when they are specific: "There is a drug called cychlorphine in the pills right now that test strips miss, and it can take more than one Narcan dose." That is information a friend can use, unlike a general lecture.
• Watch for the "revived and fine" trap. Someone who is revived should not be left alone for the next several hours.

Where to get help

• 988 Suicide & Crisis Lifeline — call or text 988 for any mental health or substance-related crisis, 24/7.
• SAMHSA National Helpline — 1-800-662-HELP (4357), free, confidential, 24/7, English and Spanish. Provides referrals to local treatment, support groups, and sliding-scale care. TTY: 1-800-487-4889.
• Naloxone access — most state health departments offer free naloxone by mail or through community distribution programs; many pharmacies now dispense it without a prescription.
• Medications for opioid use disorder — buprenorphine can be prescribed by many primary care clinicians, including via telehealth; methadone is dispensed through licensed opioid treatment programs. Both substantially reduce overdose death risk. If you have been purchasing opioids on the street, a treatment clinician is the fastest route to protect yourself from an unpredictable supply.
• Local harm-reduction and syringe services programs — the most current information about what is actually in your local supply usually comes from these organizations, not from news coverage.

The bottom line

Cychlorphine is not a future threat; it is in the supply in multiple states right now, and the tools people have learned to trust — fentanyl test strips — do not reliably flag it. The protections that still work are unglamorous and evidence-based: don't use alone, carry multiple doses of naloxone, treat pills and unregulated herbal products as unknown, and get onto medication for opioid use disorder if you have physical dependence.

Ohio's warning is also a reminder of a broader trend: as fentanyl has been increasingly disrupted, the supply is filling with compounds that are more potent, less predictable, and harder to detect. Families who update their response plan once, now, will be prepared for whichever molecule comes next.

This article was medically reviewed by Dr. Rachel Bennett, MD. It is educational information, not a substitute for individualized medical advice. If someone is unresponsive or struggling to breathe, call 911 immediately.