In September 2013, researchers at Boston Medical Center and Boston University School of Medicine, led by Dr. Daniel Fuster, reported that among 589 primary care patients who screened positive for drug use, how often people used marijuana was not linked to more emergency room visits, hospital stays or worse health. The study, published in the Journal of General Internal Medicine, is often cited in answers to whether marijuana increases health care costs, though it measured use of care, not dollars.
The Weed Street Journal first reported this study from the university’s press release, misspelling the lead author’s name as “Foster.” This rewrite corrects that and adds what the paper did and did not show.
What Happened
The paper, “No detectable association between frequency of marijuana use and health or healthcare utilization among primary care patients who screen positive for drug use,” was published online on September 19, 2013, and in the January 2014 print issue of the Journal of General Internal Medicine (vol. 29, pp. 133-139). Fuster’s co-authors were Debbie Cheng, Donald Allensworth-Davies, Tibor Palfai, Jeffrey Samet and Richard Saitz.
The researchers studied adults at an urban safety-net primary care clinic in Boston, enrolled from May 2009 to November 2011 as part of a brief-intervention trial. Every participant had reported drug use in the previous three months. Of the 589, 84% used marijuana (29% daily or almost daily, 55% less often), 25% used cocaine and 23% used opioids. The average age was 41, and 68% were men.
After adjusting for age, sex, tobacco and other drug use, the team found no significant association between marijuana frequency and emergency department visits, hospitalization, medical conditions or self-rated health. On a 100-point health scale, daily users averaged 69.1, less-than-daily users 67.8 and non-users 68.0, according to the full paper.
What the Study Did Not Show
The authors listed clear limits. Emergency and hospital use were self-reported. Everyone in the study used some drug, so there was no drug-free comparison group, and the “non-users” of marijuana were using other substances. It was a single snapshot in time, not a long-term follow-up, and the authors wrote that it “may have been underpowered” to find an effect. They warned that the results “do not suggest marijuana use is harmless.”
The study also did not measure costs. Its outcomes were visits and hospital stays, which drive costs, but no dollar figures were analyzed.
Why It Mattered
In 2013, Colorado and Washington had just legalized adult use, and opponents warned that legalization would push up health spending. Research on marijuana’s effect on the use of medical care was thin. The Boston paper offered one data point suggesting that, at least among people already using drugs, frequent marijuana use did not translate into more hospital or emergency visits.
Legacy
The study is still cited, but it answers a narrow question about one group of patients over a three-month window. It cannot say whether marijuana raises or lowers health care costs for the general public, and larger studies since legal markets opened have looked at different groups and outcomes. For what other research says about cannabis and health, see our depression studies and amotivational syndrome studies pages. Massachusetts‘ rules are in our Massachusetts marijuana laws guide, and older reports live in our cannabis news archive.
Marijuana and Health Care Costs FAQ
Does marijuana use increase health care costs?
This 2013 Boston study found no link between how often patients used marijuana and their emergency or hospital use, but it did not measure costs and only studied people who already used drugs.
Who led the Boston University marijuana health care study?
Dr. Daniel Fuster of Boston Medical Center and Boston University School of Medicine, with senior researchers including Richard Saitz and Jeffrey Samet.
How many people were in the study?
589 adult primary care patients in Boston who screened positive for recent drug use.
Did the study say marijuana is harmless?
No. The authors wrote that their results “do not suggest marijuana use is harmless,” partly because the study had no drug-free comparison group.
Originally reported by The Weed Street Journal; rewritten and updated in October 2026 with what happened next.