“Each of these new uses of fentanyl exposed millions of Americans to the drug without evidence of an inordinate degree of harm if it was used as directed,” Dr. Lynn Webster explained in a recent column.

Only in recent years has illicit fentanyl become a scourge on the black market and given a bad name to a medication that alleviates a lot of suffering. “Mexican Oxy” and other counterfeit pills made with illicit fentanyl have been linked to thousands of overdose deaths around the country. According to a recent analysis by the DEA, one in every four counterfeit pills have a potentially lethal dose of fentanyl.

“The drug isn’t designed to be put in a pill like that, and it takes very little of it to kill someone. And the illicit drug makers don’t have the kind of quality control measures that pharmaceutical companies have either,” Campman added.

Federal prosecutors have called San Diego the “fentanyl gateway” to the U.S. because the city is near ports of entry in southern California that are major transit points for Mexican drug cartels. In July, a drug courier was pulled over by an alert Texas trooper in Amarillo and found to be transporting 73 pounds of illicit fentanyl powder -- enough to kill 10 million people.

The underground fentanyl trade has also given rise to “Breaking Bad” style pill press operations.

In September, DEA agents found five pounds of pure fentanyl in the San Diego apartment of Gregory Bodemer, a former chemistry instructor at the U.S. Naval Academy, who died from an apparent overdose. Also found in the apartment was a pill press, powders, liquids and dyes used in the manufacture of counterfeit drugs.

Bodemer’s death is yet another example of how the opioid crisis has evolved from a prescription drug problem into a fentanyl crisis.

“This is how we are seeing the opioid epidemic here, mostly in the rise in fentanyl deaths,” Campman said.