The dangerous opioid fentanyl continues to contribute to overdoses in the United States, though where it’s coming from has changed in the past few years.

From 2014 to 2019, 70 to 80% of fentanyl seized by federal authorities came from China, according to a report from the U.S. Commission on Combating Synthetic Opioid Trafficking.

The Chinese manufacturers “relied on the internet to sell their drugs and on the international mail and parcel delivery systems to ship their products to the United States,” the report said.

Since 2019, however, production has shifted to Mexico, where precursors from China and other Asian countries are made into fentanyl, which is then brought by land into the U.S.

“Fentanyl coming from Mexico is often of very low purity—generally, in powder form around or slightly above 10 percent—but now accounts for almost all the fentanyl that law enforcement has seized since late 2019,” the report added.

Meanwhile, SoCal residents are overdosing on this powerful drug, some of them fatally, in what Dr. Thomas Yadegar calls the “unspoken pandemic.”

On Tuesday morning, Yadegar met with a patient at Providence Cedars-Sinai Tarzana Medical Center who actually stopped breathing as a result of ingesting fentanyl.

“I wasn’t aware of how strong that was, you know?” the patient said.

The patient, whose identity KTLA has concealed, had to be revived with Narcan, which reverses the effects of the opioid, but everyone doesn’t get that chance.

“These drug dealers aren’t trying to kill people. They’re trying to create that perfect high,” said Bill Bodner, special agent in charge of the DEA’s L.A. field office.

As part of that process, dealers are putting fentanyl into fake prescription pills and other drugs, and some people aren’t even aware they’re taking fentanyl, Bodner said.

Authorities seized 3 million counterfeit prescription pills last year, three times as many as 2020, officials said.

The drugs are often manufactured in unregulated labs across the border, where drug cartels use cheap, inexperienced workers to make fentanyl, which is easier to manufacture than cocaine or heroin and is more profitable than any other drug.

“These are drug traffickers, some of them are teenagers, some of them are being forced to do the work, from what our investigators tell us in Mexico,” Bodner said. “It’s an extremely, extremely dangerous environment.”

Alejandro Hope, a Mexican security analyst, said the manufacture of fentanyl is a game-changer for the cartels, and it will likely take work on both sides of the border to curb its growth.

“Just trying to suppress it on the Mexican side of the border is likely to prove futile. You need a more broad-based strategy that also deals with the additional demand in the U.S.,” he said.

In the meantime, doctors in the U.S. are fighting each day to save lives, but Yadegar knows the odds may be against them.

“It’s depressing to know this may just be the tip of the iceberg and we may all have to deal with it more and more over the next year,” he said.

While the patient Yadegar met with on Tuesday has vowed to get clean, the doctor knows he’ll need some luck on his side.

“Hopefully, we’ll never have to see you in the emergency room again,” Yadegar told him.

“Yeah, at least not for that kind of s—,” the patient replied.