Illicit fentanyl use is more than double medical use in US

The scale of the illicit fentanyl market in the U.S. has long remained a blind spot for public health systems. Separating legitimate medical exposure from illegal consumption has proven difficult because illicit drug use typically occurs outside clinical settings.

To measure that hidden gap, researchers at The Ohio State University conducted what is described as the largest study to date quantifying and comparing medical versus illegal fentanyl use nationwide. The findings reveal a stark disparity in how the synthetic opioid is consumed across the country.

What the Ohio State Study Found Across 300 Million Patients

Drawing from Epic Cosmos, a vast electronic health record dataset encompassing approximately 300 million patients, investigators examined data for nearly 300,000 individuals screened for fentanyl exposure between 2015 and 2023. By linking urine drug test results with medication records, the research team sorted patients into two distinct groups.

Individuals who tested positive for fentanyl and possessed a documented prescription for the drug within 72 hours prior to their screening were classified as medical-source patients, numbering 85,535. Those who tested positive but had no recent prescription history made up the illicit-source cohort, totaling 210,193 individuals.

The analysis showed that illicit-source users constituted 71.1% of the study cohort, compared to 28.9% for medical-source users. Fentanyl itself is a synthetic opioid estimated to be up to 50 times stronger than heroin and 100 times stronger than morphine.

Zhang added that discovering illicit use reached roughly 70% among all fentanyl users came as a surprise, helping make a previously obscure phenomenon visible to the broader healthcare system. First author Seungyeon Lee noted that inferring or characterizing individual-level illicit fentanyl exposure poses significant challenges because illicit use often occurs outside the clinical setting according to details reported by The Ohio State University.

Comparing Overdose Risks and Regional Hotspots

Beyond categorizing users, the research tracked adverse outcomes over time, including nonfatal overdoses, misuse, abuse, and physiological dependence leading to withdrawal. The temporal analysis demonstrated that illicit fentanyl users experienced a markedly higher prevalence across every negative category.

By 2023, the prevalence of nonfatal overdose among illicit users reached 18.6%, which was four times higher than the 4.3% recorded for medical-source fentanyl patients. Short-term risk assessments further showed that initiating illicit-source fentanyl carried a two- to three-fold higher risk of nonfatal overdose, abuse, and dependence within 30 days compared to medical-source initiation.

Geographically, the study mapped where users were most heavily concentrated. Ohio recorded the highest proportion of illicit-source fentanyl users at 12.2%, followed by Massachusetts at 10.5% and California at 8.8%. Conversely, medical-source exposure appeared most common in North Carolina at 10.6%, Ohio at 10.5%, and California at 10.3%.

Counterfeit Pills and Street Market Dangers in Colorado

Public health agencies on the ground face similar urgency regarding how illicit fentanyl is packaged and distributed. Boulder County Public Health issued warnings following the discovery of a powdered form of fentanyl circulating locally, while state authorities noted a broad influx of the drug over the past year.

Drug traffickers frequently mix fentanyl into other substances or press it into counterfeit pills designed to mimic standard pharmaceuticals such as Xanax or Oxy/M30s. Drug Enforcement Administration testing indicates that nearly half of all tested counterfeit pills contain a lethal dose.

Experts consider 2 mg of fentanyl to be a lethal dose, yet many counterfeit pills contain up to 5 mg. Because these illicit products are manufactured without pharmaceutical oversight, buyers often consume the drug unknowingly.

Public health guidelines emphasize that anyone purchasing drugs outside a licensed pharmacy—whether street-level narcotics or counterfeit prescription medications—assumes severe risk. To combat accidental overdoses, institutions like the University of Colorado Boulder provide free naloxone distribution through health promotion offices, alongside medical amnesty policies designed to encourage callers to dial 911 during emergencies without fear of campus disciplinary sanctions, as detailed by the University of Colorado.