Dangerous New Opioids Raise Overdose Risk

San Francisco health officials said a fatal overdose this month involved two non-fentanyl synthetic opioids that had not been documented in the city before. (sf.gov) The San Francisco Department of Public Health identified the drugs as N-propionitrile chlorphine, also called cychlorphine, and N-desethyl isotonitazene in an April 2026 overdose death. The department issued a clinician health alert on April 23 and a public warning on April 24. (sf.gov 1) (sf.gov 2) Officials said the person is believed to have taken counterfeit pills containing those opioids and ethyl bromazolam, a benzodiazepine not approved by the Food and Drug Administration. Fentanyl was not detected in the San Francisco medical examiner’s toxicology testing for that case. (sf.gov) Synthetic opioids are lab-made drugs that act on the same brain receptors as heroin, oxycodone, and fentanyl. They become especially dangerous in street pills because users cannot tell by sight, taste, or packaging what dose or drug they are taking. (dea.gov) (sf.gov) San Francisco said cychlorphine is estimated to be 10 times more potent than fentanyl and is not detectable with fentanyl test strips. That means a person could use a strip, get no warning, and still be exposed to a far stronger opioid. (sf.gov) Nitazenes are one of the newer opioid families showing up in U.S. drug markets. The Drug Enforcement Administration said nitazenes can match or exceed fentanyl’s potency and are often only identified after laboratory testing. (dea.gov) The federal warning system has also been tracking other additives in the illicit opioid supply this month. On April 2, the Centers for Disease Control and Prevention warned that medetomidine — a veterinary sedative not approved for human use — is increasingly being detected in the illegal fentanyl supply and can cause prolonged sedation and severe withdrawal. (cdc.gov) San Francisco’s medical examiner reported 148 preliminary accidental overdose deaths from January 1 through March 31, 2026. In those first three months, the office separately counted overdose deaths involving xylazine, bromazolam, medetomidine, and fluoro fentanyl. (sf.gov) The city reported 635 unintentional overdose deaths in 2024 and 621 preliminary overdose deaths in 2025. Monthly totals remain fluid because some cases are still under investigation. (sf.gov 1) (sf.gov 2) (sf.gov 3) Health officials said naloxone can still reverse overdose from these non-fentanyl opioids, and they urged people to call 911 even if someone responds after a dose. They also said the safest move is to avoid any pill not dispensed by a licensed pharmacy. (sf.gov) The city’s warning is blunt: counterfeit pills in San Francisco are now turning up with opioids beyond fentanyl, and a single pill can be fatal. (sf.gov)