‘Surprise’: Illicit Fentanyl Use More Than Doubles Medical Use In US, New Study Shows

Illicit use of fentanyl is now more than double its medical use in the U.S., according to a newly released study.

The study, published in eClinicalMedicine, also suggests that the risk of a nonfatal overdose is up to three times higher in individuals using fentanyl illegally compared to patients exposed to the synthetic opioid in a medical setting or via a prescription, according to a Monday press release from Ohio State News.

“Fentanyl is a big problem, but we don’t actually know how serious illicit drug use is compared to medical use,” co-lead study author and director of Ohio State University’s Artificial Intelligence in Medicine Lab Ping Zhang said in the release. “Finding that illicit use has reached 70% among all fentanyl users is a surprise. And this is also a contribution of this paper.”

“To make something that’s been a black hole visible to the healthcare system is significant,” Zhang continued.

The study’s first author Seungyeon Lee, who is a PhD student in Zhang’s lab, conducted the analysis connecting results from urine drug tests with medication records to categorize patients by medically based or illegal fentanyl use, per the news release.

“Inferring or characterizing individual-level illicit fentanyl exposure poses significant challenges because illicit use often occurs outside the clinical setting and therefore is not directly observed in clinical data, so it’s difficult to measure the scale and impact,” Lee said in the release. “This study focused on identifying illicit-source fentanyl use and its risk for opioid-related harmful outcomes.”

The study’s authors also noted that “these patterns indicate that illicit-source fentanyl remains a significant and growing threat to public health nationwide.”

Fentanyl is notably 50 times stronger than heroin and 100 times more potent than morphine, according to Get Smart About Drugs. Moreover, synthetic opioid deaths involving fentanyl declined from 48,913 in 2024 to 38,084 in 2025, the White House said in a July 13 press release.