A rising class of synthetic opioids known as nitazenes is contributing to a growing number of overdose deaths across North America, according to recent reports by drug enforcement and public health experts.
Originally developed in the 1950s as pain relievers, nitazenes were never approved for medical use due to their dangerously high overdose potential. Now, decades later, these substances are appearing in illicit drug markets worldwide, particularly in the United States.
A report from the Inter-American Drug Abuse Control Commission (CICAD) warns that nitazenes—also referred to as benzimidazole-opioids—are becoming increasingly prevalent across the Americas. The most common variant is isotonitazene (ISO), though at least a dozen other forms have been identified.
The U.S. Drug Enforcement Administration (DEA) currently lists ISO and seven other nitazenes as Schedule I substances, the most restrictive drug category, indicating a high potential for abuse and no accepted medical use.
Corey Gamberg, executive director at the Massachusetts Center for Addiction, says nitazenes are mainly produced in illicit labs in China and India before being smuggled into the U.S. through the same routes used to traffic fentanyl.
“These drugs are cheap to make and easy to transport, which makes them highly attractive to traffickers—especially as fentanyl enforcement tightens,” Gamberg explained. “It’s a pattern we’ve seen with other synthetic opioids.”
Nitazenes are sold in various forms—pills, powders, sprays—and can be snorted, smoked, injected, or taken orally. What makes them particularly lethal is their potency. Some types are up to 10 times stronger than fentanyl and hundreds of times more powerful than morphine, according to Dr. Jonathan Avery of NewYork-Presbyterian/Weill Cornell Medical Center.
Compounding the danger is the fact that most users are unaware they’re consuming nitazenes, as the drug is often mixed into heroin, pressed pills, or stimulants, making unintentional overdoses more likely.
Testing remains a major obstacle. While test strips exist to detect nitazenes in drugs, definitive testing is limited and often inaccessible. “Routine hospital and workplace drug screens typically do not detect nitazenes,” warned Dr. Ryan Marino, a toxicologist at Case Western University.
Experts stress that naloxone (Narcan) can reverse nitazene overdoses, but multiple doses may be necessary due to their strength. Public education, expanded naloxone distribution, and investment in rapid drug-checking tools are urgently needed to stem the tide of overdose deaths.