UCLA-led researchers say people who regularly use illicit fentanyl in Los Angeles are taking on opioid doses with a morphine equivalence averaging roughly 8,887 milligrams per day, a level far beyond what current addiction-treatment guidelines anticipate. The modelling study suggests the extreme tolerance that comes with that kind of exposure may help explain why many patients struggle to start or stay on medications for opioid use disorder.
Study snapshot
According to UCLA Health, researchers with Drug Checking Los Angeles paired community drug-checking results with short surveys of people who regularly use fentanyl to estimate daily opioid exposure. The university’s release notes that the work was published in the peer-reviewed journal Drug and Alcohol Dependence and lists Morgan Godvin as lead author and Chelsea Shover as the study’s senior author.
How researchers turned street samples into morphine equivalents
The paper describes measuring fentanyl and fluorofentanyl purity with liquid chromatography–mass spectrometry, then combining those purity values with self-reported daily quantities and route-specific bioavailability to calculate morphine milligram equivalents (MME). Using a bootstrapping model to account for uncertainty, the authors report a mean estimated daily intake of about 8,887 MME and detail testing of 509 samples alongside survey responses from 47 regular users, per the study in Drug and Alcohol Dependence / medRxiv.
How that compares to a “lethal” dose
The study’s headline finding, summarized in a recent release, works out to an average fentanyl exposure the authors say is roughly 60 times the 2 milligrams often cited as potentially lethal for an opioid-naive person, per EurekAlert!. The U.S. Drug Enforcement Administration cautions that as little as 2 milligrams of fentanyl can be deadly depending on body size and tolerance, and that counterfeit pills and some street samples have contained doses at or above that level.
Treatment implications
Medications such as methadone and buprenorphine remain the standard of care and are shown to reduce overdose deaths, according to NIDA. The study’s authors add that the extremely high daily exposures seen in Los Angeles help explain rising reports of very high opioid tolerance and make both induction onto medication and withdrawal management more challenging, a reality that lands directly on local clinics and harm-reduction programs.
Limitations and local meaning
The researchers flag important caveats. The sample comes from a voluntary, convenience group using a community drug-checking service, so it may not represent everyone who uses fentanyl in Los Angeles. They also note that Los Angeles’s drug supply, routes of use and co-adulterants differ from those in other regions, so the results are best read as a strong signal about high exposure rather than a precise national average, as summarized by EurekAlert!.
Authors, funding and next steps
The work was led by Drug Checking Los Angeles and supported in part by the CDC’s Overdose Data to Action program along with grants from NIDA and NIH, the release says. “Now, we find that people are regularly exposed to doses of opioids that would have seemed impossible to me before I started this work,” senior author Chelsea Shover said in a statement to UCLA Health. The team urged expanded drug checking, wider naloxone access and low-barrier access to medications for opioid use disorder to help clinicians and communities respond.
