When fentanyl started polluting the drug market, overdose deaths began to soar. The staggering toxicity of fentanyl, some 50 to 100 times more potent than heroin, makes an overdose too easy. Lethal amounts cling to tools used in the manufacture, sale, and distribution of cocaine, “Xanax,” MDMA, ketamine. This synthetic opioid slows your breathing until it quietly stops altogether. To your friends, it might look like you had one too many drinks, but really, you’re dying. It kills heroin users and people who have never swallowed a Vicodin alike. Two milligrams is often fatal.
Just when it seemed no drug could surpass fentanyl in lethality, an even deadlier narcotic is emerging.
So new, it doesn’t have a street name yet
At any time, the potency of street narcotics reflects whatever society drives its members toward numbness and ultimately death. What NA won’t tell you but many addicts will is that addiction is a story of adaptation gone too far. Few places force one to adapt as intensely as San Francisco. The city is in the decades-old clutches of an opioid crisis whose invisible grip may be tightening.
For now, fatal overdoses in San Francisco continue to decline from the record high in 2023. That year, at least 800 people citywide overdosed and died, with fentanyl contributing to most deaths. Fentanyl continues to take lives, if at a less-than-all-time high. However, one report from the San Francisco Public Health Department confirms the first fatality caused by a new synthetic opioid.
N-propionitrile chlorphine (cychlorphine) and N-desethyl isotonitazene (norisotonitazene, or iso) are two relatively new synthetic opioids even stronger than fentanyl. These drugs are so new, they don’t even have street names yet. The accepted lethal dose of fentanyl is two milligrams. A lethal dose of cychlorphine is measured in micrograms. The victim in SFDPH’s report also ingested ethyl bromazolam, a non-FDA approved benzodiazepine. Mixing opiates and benzos is especially dangerous because both drugs compound the other’s effects.
Surely we’re familiar with this widely circulated image of the average lethal fentanyl dose poised on the tip of a No. 2 pencil. A lethal dose of cychlorphine would barely be visible.
Cychlorphine is so new, SFDPH director of substance use Dr. Phillip Coffin(!) says it isn’t even on hospital radar. He also told the Chronicle that patients seeking treatment for opioid use disorder at SF General are not currently screened for it. Cychlorphine belongs to a new class of synthetic opioids not chemically analogous to morphine called “orphines”—orphans of morphine. Fentanyl marked a departure from opium distillation. What if cychlorphine is just one step into a realm of potentially endless molecular replication?
The margin of error between ‘high’ and ‘dead’ is virtually nonexistent
Fentanyl has already killed dozens in San Francisco and is linked to many overdoses throughout the United States. From July 2025 to February 2026, fentanyl took 41 lives in Tennessee alone. I dread the day cychlorphine enters the supply chain. With this new drug, the margin of error between ‘high’ and ‘dead’ is virtually nonexistent.
No doubt having zero access to comprehensive healthcare only aggravates the opioid crisis that haunts San Francisco and elsewhere. Is it so unimaginable that someone with no insurance who suffers from chronic pain and poor mental health would seek their medications on the streets of the Tenderloin? In fact, one American Journal of Public Health study found that uninsured people are somewhat likelier to develop substance dependencies.
Not once in history has turning to hard drugs been simultaneously so appealing and dangerous. Narcan lets us think there’s a failsafe, on modest standby while cocaine disappears up people’s noses. It remains to be seen whether that coke is laced, whether Narcan is effective against this unbelievably potent new class of opioids. Fatal overdoses are down by over a quarter of where they were this time last year. According to the city's Chief Medical Examiner, from January to March 2026, San Francisco officially recorded 148 fatal ODs.
