The first time Nicki Saccomanno used fentanyl, she overdosed.

It was 2016, and the 38-year-old from Kensington hadn't known that the drugs she'd bought had been cut with the deadly synthetic opioid. She just remembers injecting herself with a bag, and then waking up surrounded by paramedics frantically trying to revive her.

Saccomanno, who has been addicted to heroin for 10 years, was shaken. But, before long, there was barely anything else to take but fentanyl to stave off the intense pain of withdrawal. Every corner, it seemed, was selling it. Saccomanno and other longtime heroin users found themselves forced to adapt.

For younger users, like the twentysomethings who live in the camps off Lehigh Avenue, fentanyl is all they've ever known. Like others before them, many graduated from using legal painkillers to illicit opioids in the last few years -- except when they turned to the streets to feed their addictions, they were buying a drug much more powerful than their older counterparts had started on.

Young and old are paying for it with their lives. Fentanyl was present in 84 percent of Philadelphia's 1,217 fatal overdoses last year, and in 67 percent of the state's 5,456 overdose deaths in 2017, according to a wide-ranging report on the state of the opioid crisis in Pennsylvania released recently by the U.S. Drug Enforcement Administration.

The report shows how, over the last five years, the opioid crisis ballooned into an overdose crisis -- how fentanyl contaminated the state's heroin supply, overwhelmed county morgues with overdose victims, and shocked advocates, people in addiction, and law-enforcement officials alike with its sudden ubiquity.

But to all of them, the explosion of fentanyl makes a kind of terrible sense: Fentanyl is significantly cheaper to produce than heroin. It draws a significantly larger profit. It's significantly more powerful and more addictive than heroin, even Kensington's supply, which has long been known as the cheapest and purest in the country.

These days, Saccomanno uses a combination of heroin and fentanyl, even though she hates it.

"You get sicker," she said. "You need to get more fentanyl more often. It makes being able to get well and stay well even harder. But you can't find anything else."

'A dramatic shift'

Pure economics.

That's what law-enforcement officials say is driving the rise of fentanyl in Pennsylvania.

It has legitimate use as a drug to treat serious pain, like that in cancer patients, and has been on the illicit drug market for at least 15 years, said Pat Trainor, spokesman for the Philadelphia branch of the DEA. But it mostly turned up in unusual overdose rashes and would disappear from the scene again.

"Two or three years ago, we really saw a pretty dramatic shift," Trainor said. "It was initially seen as a cut or an adulterant in low-quality heroin, and it's really shifted now that it's pretty much largely -- but not completely -- replaced most of the heroin supply in Philadelphia."

In Philadelphia, he said, a kilogram of heroin, or 2.2 pounds, sells for $50,000 to $80,000, and a drug trafficker can make about $500,000 in profit off it. A kilogram of fentanyl sells for $53,000 to $55,000, is 50 to 100 times stronger, and can turn a profit of up to $5 million.

"For a lot of drug-trafficking organizations, it's that simple," said Trainor.

Most of the fentanyl that ends up in Pennsylvania is manufactured in China and smuggled through Mexican drug-trafficking organizations into the United States along the same routes used to traffic heroin, according to the DEA report.

People have also tried to make it closer to home, however. Unlike heroin, which is derived from opium poppies, fentanyl and its analogues can be produced in a lab. Earlier this year, DEA agents raided what they thought was a methamphetamine lab in a hotel room in western Pennsylvania. To their surprise, it turned out that the room's occupant had been trying to make fentanyl.

Seeking out fentanyl

Earlier this year, researchers from the Philadelphia Department of Public Health, conducting a survey of opioid users at Kensington's needle exchange, posed a question to 400 people in active addiction.

They knew that most of the city's heroin supply had already been tainted with fentanyl, and wanted to know how people in addiction were reacting. And so they asked drug users what they would do if they knew that fentanyl was in the drugs they were buying.

The answers they received shocked them. Of the drug users the Health Department surveyed, 45 percent told researchers that they weren't trying to avoid fentanyl at all -- that they would be more likely to use a bag of fentanyl.

"There was more acceptance -- it had become part of the community in a way it hadn't been initially. It was actually something people were going for because it was an enhanced high," said Kendra Viner, manager of the department's Opioid Surveillance Program. "And people between 25 and 34 years old were significantly more likely to say they would seek out fentanyl."

A woman who identified herself as "Shy," a longtime heroin user along Kensington Avenue, said she tries to test her heroin for fentanyl, but often resigns herself to the fact that she can't find anything else to stave off withdrawal.

In interviews on Kensington Avenue in recent weeks, drug users said they felt they didn't have much choice: Though the rush of a fentanyl high might have initially felt stronger and better than heroin, it also made returning to heroin difficult. Even though fentanyl was more dangerous, they said, their tolerance for opioids has become so high that heroin was not enough to stave off withdrawal.

"Before, people were scared of fentanyl, people wouldn't do it -- but now my body is hooked on it," said Kia, a 23-year-old interviewed near the Emerald Street encampment last week. "If I wake up and don't do heroin cut with fentanyl, I'm still sick."

Physicians and addiction researchers have been advocating for some time for more research on how common medication-assisted treatments used to treat heroin addiction work for people who are now accustomed to a drug much stronger than heroin. Viner said more research on fentanyl trends in general is needed -- for example, her survey focused only on drug users in Kensington who use the neighborhood's needle exchange. It's harder to track the habits and preferences of the hundreds of people from around the city and suburbs who fly under the radar, coming to the neighborhood just to score.

Still, the DEA wrote in its report, the findings in Philadelphia -- echoed by treatment providers and people in addiction across the state -- are deeply alarming. They're a sign that a tainted drug supply is driving demand -- not the other way around.

William, a Bensalem man who came to Kensington earlier this week for fentanyl, as he has for the last four months, said he felt trapped by a drug he hadn't necessarily sought out -- one that he now needs to function, one that is killing his friends and loved ones.

"Withdrawal -- imagine the worst flu you've ever had," he said -- then increase that pain by 10. "And you know that that one thing you hate -- the thing that makes you feel this way -- is the only thing that will make you feel better."