While the dangers posed by fentanyl have dominated the headlines for years, the number of deaths from another class of particularly potent synthetic opioids called “nitazenes” has been steadily rising. For decades, knowledge of nitazenes, also known as benzimidazole opioids, was limited to those studying opioid pharmacology, but that all changed in 2019 when the drugs appeared on the illegal street drug market, first in Europe and then in the United States. Starting in eight countries, by 2022 it has spread to 19. According to the United Nations Office on Drugs and Crime in 2025. According to the World Drug Report, the presence of nitazenes in the illicit drug market has been increasing over the past five years and poses an increasing threat to public health. However, it is not clear how the nitazenes entered the world drug supply, as there was never a public demand for these drugs.
Deaths from nitazene overdose are of greatest concern. That’s partly because isotonitazene—the most common drug, nitazene, also known as “ISO”—is five to nine times more potent than fentanyl, which is typically 25 to 50 times more potent than heroin, which is roughly twice as potent as morphine. That means less than 2 mg of ISO — the equivalent of a pencil tip or a few grains of sand — can kill you, says Brian Townsend, a retired Drug Enforcement Administration (DEA) supervisory special agent and founder and president of Only 2mg Inc., a nonprofit that fights the abuse of fentanyl and other drugs of abuse.
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Currently, there are limited data on the number of deaths from nitazene in the United States. The closest we have are the findings of two studies, although neither was able to provide detailed estimates of nitazene deaths worldwide and likely underestimate the extent of nitazene overdoses in America. The first found that nitazenes were responsible for at least 200 overdose deaths in Europe and North America in 2020-2021. In the second 2022 93 deaths were identified from eight case reports, mostly from the United States.
Here’s what you need to know about nitazenes, why they’re growing, and their public health implications.
What are nitazenes?
Nitazenes are a class of potent synthetic opioids developed in the 1950s as an alternative to morphine, but were never approved for medical use due to their potential for overdose. Rolling Stone. Fentanyl was developed during the same period, he adds.
“They are not related to opioids derived from morphine or fentanyl, but act similarly by acting on opioid receptors, causing effects such as analgesia, euphoria, sedation, respiratory depression, and even overdose and death,” says Ryan Marino, MD, a toxicologist at University Hospitals in Cleveland and an expert in addiction medicine.
Nitazens come in a variety of forms, including tablets, powders and sprays, both “pure” and mixed with other drugs such as heroin, fentanyl and benzodiazepines. Nitazens can be taken intravenously, nasally, orally, sublingually, and by inhalation (vaporization).
Nitazens work by binding to opioid receptors to stop or reduce the intensity of pain, just like heroin, fentanyl, or other opioids, Townsend explains. “The problem is that they are very strong and slow down the part of your brain that tells you to breathe,” he explains. “It causes respiratory depression. We sometimes call it ‘sleeping death.’
In the US, clonitazen and etonitazen, two types of nitazene, were included in the original 1971 Controlled Substances Act as Schedule 1 drugs that have a high potential for abuse and are not currently medically acceptable. in 2020 The DEA classified isotonitazene as a Schedule 1 substance, and seven other nitazenes have since been similarly listed.
Despite being illegal, the law is difficult to enforce. “The chemicals that make up nitazenes are relatively inexpensive, and they’re also readily available and inexpensive to produce, which is why it’s become increasingly popular in communities around the world,” says Jessica Steinman, chief clinical officer at No Matter What Recovery in Los Angeles.
It’s also difficult to get accurate numbers to show the extent of the problem because we can’t reliably detect nitazenes. “Standard fentanyl test strips do not pick up nitazenes, and most hospital toxicology panels do not have them, which means overdoses are misidentified and deaths are underreported,” says Jason Bernstein, LMFT, director of detox/residential and dual diagnosis outpatient clinics at Clear Behavioral Health. “For people managing addiction, it’s destabilizing because harm reduction strategies fail when you can’t try the most dangerous thing on offer.”
According to Marin, it’s not clear why nitazenes entered the drug supply in the first place, and people aren’t looking for them, and there’s no known demand for them. “They may be a response to efforts to reduce the supply of other opioids and even other drugs such as benzodiazepines,” he says. Rolling Stone. “In almost every case where nitazenes are found, they are added to other drugs, primarily fentanyl, and are not advertised as being sold in them. Between 2019 and 2023, nitazenes have been identified in at least 4,300 drug seizures by law enforcement in the United States.”
While we don’t have a complete picture of nitazene deaths, we do know that they are happening across the country. For example, a study conducted in 2022 and 2023 found nitazenes in wastewater samples from Washington and Illinois. The Ohio Department of Health reported seven Nitazen overdose deaths in the state in 2020, 2021 and 2022. – an average of 57 deaths, and in the first six years of 2023 months – 77.
Although in 2019 There were no nitazene-related deaths in Tennessee, 2020-2023. there were 92. Most of the overdoses involved fentanyl. In addition, as of 2020, the Pennsylvania Department of Health reported at least 50 fatal overdoses involving nitazenes, and in 2024 – a record 29 deaths.
Like other opioids, naloxone can reverse a nitazene overdose. However, due to the potency of nitazenes, multiple doses of naloxone may be required.
According to Justin Gurland, a licensed primary social worker specializing in addictions, there is no specific demographic that intentionally seeks out nitazenes. “That’s part of what makes them so dangerous,” he says Rolling Stonee. “Most people who use them don’t even know they’re using them. Nitazens are mixed with heroin, counterfeit pain pills and even non-opioid drugs, so they reach people who were never going to use opioids.”
Why are nitazenes released?
Nitazens are becoming increasingly popular because they are inexpensive, potent, and addictive, Townsend says. “They’re cheap, so drug dealers ‘cut’ their drug supply and make more money,” he explains. A lot of people struggling with substance abuse have told me that’s what they’re looking for. [for] stronger highs. Finally, they are addictive, which means repeat customers and more money for the drug dealers refilling these poisons. And because of the potency of nitazenes, “doses can be very small, making them easy to hide or transport from one place to another,” Steinman says. Rolling Stone.
Many experts believe that nitazene analogs may have entered recreational drug markets to replace fentanyl analogs after fentanyl analogs were banned in China and the United States, says Marthe M. Vandeputte, a researcher at the toxicology laboratory at Ghent University in Belgium.
in 2025 July 1 China has imposed a blanket ban on nitazene analogues. “This means that once scheduled, the vast majority of nitazenes known to date were illegal in China, which is known to be the main country of production,” says Vandeputte. Rolling Stone. “Given China’s significant role in the production of nitazenes, we expect that this could have a significant impact on the new synthetic opioid market in the coming years, as fewer new nitazene analogs may enter the markets. But she says we may see the emergence of other classes of synthetic opioids instead.”
“Furthermore, the 2022 Taliban ban on opium poppy cultivation could affect the supply of heroin in Europe and elsewhere, which could further fuel the growth of synthetic opioids such as nitazenes,” she says.
Why are people concerned about nitazenes?
As of 2019, more than 20 different variants of nitazene have appeared, with new ones appearing all the time. “Once a single compound is designed, manufacturers tweak the molecule a little bit and produce something that’s not technically illegal yet,” says Bernstein. “What started with heroin has now spread to stimulants, depressants and counterfeit drugs. If you buy any street drug right now, you’re putting yourself at risk.”
Luke Archibald, M.D., chief of addiction psychiatry at Dartmouth Hitchcock Medical Center in New Hampshire, is concerned about all the unknowns surrounding nitazenes — especially since they’re made up of groups of chemicals that can have different properties, such as different potency and responses to naloxone. “The concern is that we don’t know what may be in any particular item, and there are reports of nitazenes in counterfeit pills that may be marketed as other substances and ingested by opioid naïve individuals,” he says. Rolling Stone.
The strength of Nitazen is also a concern. “Even a small amount—a dose small enough to fit on the tip of a pin—can slow or stop breathing,” says Gurland. “And the difference between a ‘dose’ and a fatal overdose can be microscopic.”
According to Gurland, the biggest concern is that most people using them don’t know they’re using them because nitazenes are found in counterfeit pills and powders mixed with oxycodone, heroin or even non-opioid drugs. “For people already living with addiction, the unpredictability of every use can be fatal. It’s not just about strength, it’s about invisibility,” he explains. “They’re hard to detect and labs often don’t test for them. That’s why they’re being called the next wave of the synthetic opioid crisis.”
Like fentanyl, nitazenes are rapidly becoming a public health concern. “That combination of strength and stealth is what makes them so dangerous,” says Gurland. “People don’t know what they’re taking, first responders don’t always know what they’re dealing with, and standard drug tests can miss them. So there’s this invisible risk that can spread to communities already stretched by the opioid crisis.”
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