U.S. authorities warned in late 2025 of a resurgence of carfentanil across the country, with hundreds of drug users overdosing on the synthetic opioid that officials say is 10,000 times more potent than morphine and 100 times stronger than fentanyl. The resurgence coincided with the Chinese government's crackdown on the sale of precursors used to make fentanyl.

Overdose deaths involving carfentanil nearly tripled in 2024 compared with the previous year, reaching 413 deaths across 42 states and Washington, D.C., according to CDC data. In October 2025, the DEA Los Angeles Field Division seized 628,000 pills containing carfentanil. In September 2025, officials in Washington state seized more than 50,000 counterfeit M30 pills that contained a mixture of carfentanil and acetaminophen.

"You're talking about not even a grain of salt that could be potentially lethal," said Frank Tarentino, chief of operations for the DEA's northeast region. The DEA's annual quota for lawfully manufactured carfentanil is 20 grams.

DEA intelligence bulletins indicate that the Chinese regulations are likely prompting traffickers in Mexico to use carfentanil to boost the potency of a weakened version of fentanyl. Traffickers in Mexico may be producing carfentanil themselves, and some procure it from China-based vendors circumventing regulations by placing ads on online forums in other countries, according to authorities. About a decade ago, carfentanil caused hundreds of overdoses in North America before its prevalence declined after China banned it.

"You can't just dabble in this," Tarentino said. "This is not some mad scientist on Reddit you're going to get to go out to a rudimentary laboratory in Mexico to make carfentanil."

Michael King Jr., founder of the Opioid Awareness Foundation, said: "It's like a biological weapon. If the world thinks we had a problem with fentanyl, that's minute compared to what we're going to be dealing with with carfentanil." Russian forces deployed carfentanil as a chemical weapon against Chechen separatists in 2002.

Drug czar Sara Carter addressed traffickers in remarks on the resurgence. "Anyone who takes a pill that is not prescribed to them by their doctor is playing a game of Russian roulette with their life," she said. "But if those terrorists think they can continue this chemical warfare without consequences, they are wrong."

U.S. Customs and Border Protection reported that fentanyl seizures in 2025 were about 12,000 pounds (5,443 kilograms), less than half the amount seized in 2023. The DEA's proposed budget for the upcoming fiscal year includes a $362 million increase centered on cartel-driven fentanyl trafficking.

Days before Thanksgiving 2025, Michael Nalewaja and a mutual friend unknowingly took a lethal mixture of fentanyl and carfentanil that they may have mistaken for cocaine. Nalewaja, who had worked as an electrician in Alaska nearly two decades after entering rehab for drug addiction as a teenager, died as a result. His mother organized a town hall in El Dorado Hills, California, with local officials and other mothers who had experienced similar losses, instead of holding a large funeral, and is advocating for legislative and judicial changes to prevent deaths caused by carfentanil.