The use of a newer class of opioids, nitazenes, is growing across the US. Once rarely seen in illicit markets before 2019, the drugs have been found on nearly every continent at this point. Their elevated potency—250 to 900 times stronger than morphine for the most common nitazene—makes them far deadlier than heroin and fentanyl. Can we slow or stop the use of these opioids before they do more damage?