Nitazenes are a class of synthetic drugs 40 times more potent than fentanyl that have caused hundreds of confirmed deaths across Europe and the US since appearing on the radar of law enforcement agencies in 2019. It’s difficult to say exactly when nitazenes started being commonly sold as street drugs—identifying them requires specific tests that are not routinely performed—but law enforcement agencies started noticing them about six years ago. A shipment of one type of these synthesized molecules—isotonitazene—was intercepted in the US Midwest in 2019, and deaths started being reported in both the US and Europe over the following years. Europe, for its part, has always been a market dominated by heroin, with almost all of this coming from Afghanistan. As stockpiles of opium run out, it is possible that there will be a shortage of heroin in the European market that synthetic opioids could fill.