Los Angeles Study Reveals Extreme Fentanyl Exposure Among Regular Users

A modeling analysis using >500 fentanyl samples collected by Drug Checking Los Angeles between September 2023 and January 2026 and surveys of 47 regular users estimated a daily intake of 8,887 morphine milligram equivalents (MME). This corresponds to roughly 440 Percocet pills or the opioid content of more than 1,200 100-µg hospital fentanyl vials—about 60 times the dose lethal for an opioid-naïve person.

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

Since 2023 fentanyl has supplanted heroin as the dominant street opioid in the United States, its high potency drives users to consume doses far beyond clinical norms and fosters rapid tolerance that hampers initiation and retention on medication-assisted treatment (MOUD). The study was led by UCLA associate professor-in-residence Chelsea Shover, founder of Drug Checking Los Angeles, with lead author Morgan Godvin, a researcher with lived opioid-use disorder experience. Co-lead Dr. Joseph Friedman (UC San Diego) contributed to analysis.

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

Shover said the study turns a previously unknowable “black box” of illicit fentanyl exposure into quantifiable risk, urging clinicians to adopt withdrawal-management strategies with adjuvant therapies. Godvin highlighted the gap between clinical knowledge of pharmaceutical opioids and street-level fentanyl, calling for public-health metrics comparable to those for tobacco and alcohol.

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

The authors note that Los Angeles received illicit fentanyl later than many U.S. regions, limiting external validity, and that the voluntary, anonymous drug-checking program yields a convenience sample that may not reflect the broader user population. Data on street-level fentanyl purity are scarce—fewer than ten North American cities collect comparable information—leaving a gap in understanding whether similar exposure levels occur elsewhere.

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

• “We had been treating illicit-opioid doses as a black box — an unknowable, a curiosity,” — Morgan Godvin, Lead Author

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

• “Now, we find that people are regularly exposed to doses of opioids that would have seemed impossible to me before I started this work,” — Chelsea Shover, Senior Author

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

• “To put it in perspective, in the hospital settings, fentanyl is often dosed in 100 microgram vials. One gram of average purity fentanyl that we tested had a dose equivalent to more than that 1,200 of these vials. So people are getting daily doses that are on par with injecting hundreds of the hospital vials or taking 440 Percocet pills.” — Chelsea Shover

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

• “It’s no longer,‘how do we treat someone who smokes a gram of fentanyl per day,’ it’s ‘how do we treat someone using thousands of MMEs of oral morphine in fentanyl per day?’ That question and its answers feel more accessible, less abstract to clinicians,” — Chelsea Shover

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine

The authors recommend expanding community drug-checking programs to other cities, establishing longitudinal monitoring of fentanyl purity, and developing MOUD protocols that address ultra-high-dose withdrawal. Further refinement of exposure models and collaboration with clinicians aim to translate findings into actionable treatment guidelines.

People who use illicit fentanyl consume daily doses equivalent to nearly 9,000 milligrams of morphine