In the national conversation about overdose, fentanyl is often framed as a single, wide-reaching crisis, but new evidence from five major U.S. cities suggests a more fragmented, complex reality.
United States, February 9, 2026— In JAMA Network Open, lead researchers Nabila El-Bassel, PhD, University Professor at the Columbia University School of Social Work, and Steve Shoptaw, PhD, professor at UCLA, report that among people who inject drugs but are not in treatment, fentanyl exposure is nearly universal across five major U.S. cities, while xylazine and stimulant exposures vary sharply by location and, in some settings, are rising over time. “Prevalence of Illicit Drug Detection in 5 US Cities Among Out-of-Treatment People Who Inject Drugs” covers research on drug use patterns in New York City, Houston, Los Angeles, Philadelphia, and Washington, D.C., produced in collaboration with researchers across five universities and the HIV Prevention Trials Network (HPTN).
“Across all five cities, fentanyl exposure was nearly universal and polysubstance exposure was the rule, not the exception,” said Nabila El-Bassel, PhD, Columbia University School of Social Work.
“But what’s equally important is that xylazine and stimulants were not showing up everywhere in the same way. In some cities, xylazine is essentially saturating the drug supply, while in others it remains far less common. That geographic contrast is a public health signal and it tells us we need real-time, local drug supply surveillance and rapid, tailored harm-reduction and treatment responses that reach people who are not currently engaged in care.”
Steve Shoptaw, PhD, UCLA, emphasized why the study’s approach matters for public health strategy. “When we rely only on self-report or routine systems, we miss what’s actually happening in the drug supply, especially among people who are outside formal healthcare settings,” he said. “Biomarker-based data like these show a fast-moving, local reality. The findings support expanding mobile outreach, on-the-spot testing, and immediate linkage to care alongside harm reduction that can adapt as the drug supply evolves.”
Background:
The team analyzed urine biomarkers from 444 adults enrolled in the HIV Prevention Trials Network (HPTN) 094 study across the five focus cities for exposure to fentanyl, xylazine, stimulants, cocaine, and other substances. What emerged was a sobering snapshot of today’s drug supply: fentanyl was detected in 93% of participants, and polysubstance exposure was detected in 95%, underscoring that for many out-of-treatment people who inject drugs, fentanyl is not an occasional contaminant—it is an expected condition of the environment.
However, the study also revealed that the crisis does not look the same everywhere. Overall, xylazine was detected in 53% of participants, but the city-by-city differences were striking. Philadelphia showed near saturation (99%), while New York City (72%) and Washington, DC (76%) also had high prevalence. In contrast, Los Angeles (7%) and Houston (17%) had much lower levels—evidence that xylazine is spreading unevenly, creating different risk landscapes across the country.
The study also suggests these patterns can shift quickly. From June 2021 to September 2023, xylazine detection increased sharply in New York City, while amphetamine-type stimulant detection increased even more dramatically in Washington, DC, showing that local drug supplies can change rapidly, demanding faster, more adaptable public health responses. Exposure patterns also tracked with indicators of structural vulnerability. The researchers found that cocaine detection was higher among unhoused participants, and stimulant detection was higher among those with a recent history of incarceration, highlighting how housing instability and incarceration can intersect with substance-related risk.
Taken together, the findings reinforce a central message: the overdose emergency demands urgent national action, but effective solutions must also be local, real-time, and flexible enough to match what is happening in each city’s drug market before shifts in the supply translate into more lives lost.
Media Contact:
NAME: Nabila El-Bassel
TITLE: University Professor
PHONE: 917-209-0329
EMAIL: [email protected]