Cychlorphine is a novel synthetic opioid that is extremely potent. It has been recognized very recently and has been identified in several toxicology and overdose cases in the last 18 months. Recognizing cychlorphine effects and signs of overdose can help prevent fatalities.
- Cychlorphine is a very potent synthetic opioid, believed to be ten times stronger than fentanyl.
- Cychlorphine has been recognized in toxicology and overdose cases since 2024, and is increasingly found in the illicit drug supply in the U.S.Â
- Cychlorphine, like other opioids, can be very addictive and may require professional support to manage.
What is cychlorphine (N-propionitrile chlorphine)?
N-propionitrile chlorphine, known as cychlorphine, is a newly recognized synthetic opioid, believed to be around ten times more potent than fentanyl. It is an orphine analog, similar in structure to drugs like chlorphine and brorphine, classed as benzimidazolone opioids or nitazenes. [1][2]
Nitazenes originated decades ago but have since re-emerged as potent and unregulated substances found in the street drug supply. Often, these substances are highly potent, with some of comparative strength to fentanyl. [1][3]
Cychlorphine has been recognized in a number of toxicology and overdose cases, after first being identified in 2024. As a newly recognized substance, it is not included in standard drug screening and, therefore, may have been missed in several cases. [1][3] Overdose cases involving cychlorphine have increased since late 2025, and it is becoming more common across the US, prompting nationwide and governmental concern. [1][4]
Origins and areas most affected
A report published by the Center for Forensic Science Research and Education in January 2026 details 21 cases of cychlorphine-related fatal overdose in 8 US states: [1]
- Tennessee: 7
- Illinois: 4
- California: 3
- Texas: 3
- Nevada: 1
- Louisiana: 1
- New York: 1
- Pennsylvania: 1
A report from March 2026 indicates that cychlorphine has been identified in 19 fatal overdose cases in Tennessee, indicating that at least 12 overdose deaths involving cychlorphine have occurred in this state since January. [4]
Four cases in Canada were also identified. Among these 25 cases, cychlorphine was the sole opioid in 11 cases.
Why cychlorphine is concerning
The emergence of cychlorphine is so concerning due to its extreme potency. It is estimated to be ten times more potent than fentanyl. Fentanyl has contributed to a huge increase in overdose deaths in the last decade, related to intentional and unintentional use, particularly due to contamination in the drug supply. [5]
Fentanyl is around 50-100 times stronger than heroin, which means that cychlorphine could be 500 to 1000 times more potent than heroin. Therefore, cychlorphine can be fatal in minuscule doses. If it is found as a contaminant in other drugs, and people use it unknowingly, they could be at severe risk of fatal overdose. [1][5]
Cychlorphine vs. Fentanyl and other opioids
| Potency in relation to morphine | Effects and risks | |
|---|---|---|
| Morphine | 1 | Used medicinally, dangerous in high doses |
| Heroin | 1-2 | CNS depressant effects, risks of overdose in moderate to high doses |
| Brorphine | <100 | Found as contaminant, high risk of overdose in small doses |
| Fentanyl | 100 | Used medicinally and also produced illicitly. Found as contaminant, high risk of overdose in small doses |
| Cychlorphine | 1,000 | Found as contaminant, extremely high risk of overdose in small doses |
Intoxication and overdose signs
Currently, reports of cychlorphine are limited, with much of the available data coming from overdose cases, so its full effects are not yet well understood. However, its effects are expected to be similar to other potent opioids such as nitazenes, heroin, fentanyl, and prescription opioids, but to a much higher intensity.
At lower or early stages of use, cychlorphine may cause typical opioid intoxication effects, including: [1][2][5]
- Reduced heart rate
- Confusion
- Decreased responsiveness and alertness
- Drowsiness
- Slowed breathing
- Nausea and vomiting
- Pinpoint pupils
Cychlorphine overdose
As dose or potency increases, these effects can rapidly progress into a life-threatening overdose. Signs of overdose may include:
- Severely slowed or stopped breathing
- Loss of consciousness or inability to wake
- Markedly slowed heart rate
- Pinpoint pupils
- Blue or purple lips and fingertips (cyanosis)
Due to its extreme potency, cychlorphine overdose can occur with very small amounts and may become fatal quickly. If an opioid overdose is suspected, seek emergency medical help immediately. Call emergency services, especially if the person is unresponsive or not breathing. [7]
Can naloxone reverse cychlorphine overdose?
In the event of an opioid overdose, naloxone (Narcan) can be administered. This is an opioid antagonist that works by blocking and reversing opioid effects and can potentially be lifesaving.Â
Because cychlorphine is extremely potent, naloxone can be used to assist in overdose cases, although it may have less effect on cychlorphine than it does on other opioids. However, it should still be used, as it could save the individual’s life. It may be necessary to utilize multiple doses. [7]
Cychlorphine in the drug supply
Cychlorphine is commonly found in the drug supply as a contaminant. People who produce illicit substances often use additional substances to increase production and profit. For example, fentanyl has been found as a contaminant in various types of substances, including illicitly produced opioid pills such as hydrocodone, heroin, methamphetamine, and other pills and powders. [5][7]
People who use illicit substances may be at increased risk of unexpectedly using cychlorphine and experiencing its potent effects. The risks of using a tiny amount of cychlorphine are likely to be extremely severe. If it is used in combination with other substances, particularly other CNS depressants, these risks can be dramatically increased.Â
Addiction and dependence risks
Like other opioids, cychlorphine is likely to be an addictive substance. Prolonged use can result in the development of physical dependence, which can cause withdrawal symptoms when use is stopped. Because of the high potency of cychlorphine, it is likely to result in a more rapid development of tolerance, dependence, and withdrawal. Opioid withdrawal symptoms can be unpleasant and sometimes dangerous, and may require professional intervention. [8]
Similarly, opioid addiction can have significant detrimental effects on an individual’s well-being and functioning. This can include serious health complications, impaired interpersonal relationships, and issues around employment and professional functioning. Generally, the most effective management of opioid addiction involves professional support. [8]
Harm reduction strategies
People who use opioids or other illicit substances and are not ready to utilize professional support to stop can use harm reduction strategies to reduce their potential risks, such as:
- Utilizing needle exchange programs
- Administering substances in supervised consumption sites
- Using very small doses when administering a new batch, in case of contamination or higher potency than expected
- Not using alone, and providing naloxone to companions in case of an overdose
Treatment for opioid dependence
People who use opioids of any kind, including cychlorphine, are likely to benefit from professional support to reduce and stop use. Detox and withdrawal from opioids can be severe and may result in dangerous consequences, so it can be safer to utilize inpatient detoxification services to complete this stage, where professionals can monitor and treat dangerous effects. [8]
Following withdrawal, people can benefit from rehabilitative services, which can be offered through inpatient or outpatient programs. These often include psychological therapies, opioid replacement medications such as methadone or buprenorphine, and ongoing professional support to enhance recovery.
Support groups, such as Narcotics Anonymous, can also be helpful for people in opioid recovery.
Available rehab centers can be viewed on the Recovered Directory. People may also wish to seek advice or referral from their primary care provider.
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