Federal officials have confirmed cychlorphine in at least 10 states as the synthetic opioid fuels a sharp rise in poisoning deaths, with the highest risk concentrated in the Southeast, especially Tennessee.
Experts estimate cychlorphine is about 10 times stronger than fentanyl, and fentanyl test strips cannot detect it, allowing counterfeit pills to appear "clean" while remaining potentially lethal.
Investigators say the drug is being sold on social media as fake Adderall, Xanax and Percocet, exposing teens and college students who may think they are buying study aids or anxiety medication.
Knox County has tied dozens of overdose deaths to cychlorphine, while several college students in California have died in recent weeks; deaths have also been linked to Oklahoma and Illinois.
Naloxone can still reverse a cychlorphine overdose, though multiple doses may be needed, underscoring warnings that any pill not obtained from a pharmacy should be treated as counterfeit.