Smoking, not injecting, more popular fentanyl method, UCSF study finds

San Franciscans struggling with fentanyl addiction have increasingly pivoted away from injecting the drug to smoking it instead, according to new research from UCSF published this week.

In the paper, more than 90% of participants reported currently smoking fentanyl, while around 53% reported currently injecting the drug.

“Public-health officials, harm-reduction organizations, and different research groups have been observing this transition from injecting to smoking predominantly on the West Coast, especially in San Francisco,” said Nicole Holm, one of the study’s lead authors and a research assistant at the UCSF School of Medicine.

Injection is still the primary method of using fentanyl in other parts of the country, particularly the East Coast, Holm told The Examiner. It’s still unclear why smoking has become more popular on the West Coast, she said.

Holm’s team interviewed more than 30 people recruited from three syringe service programs in The City, including the Tenderloin Center prior to its 2022 closure.

Vitka Eisen, the CEO of HealthRight 360, a health-care nonprofit that operated the Tenderloin Center, said that the paper aligned with what the center’s staff witnessed on a daily basis.

“The way we set up this space was on the assumption that about 50% of the people would be smoking, and 50% of the people would be injecting drugs,” Eisen said. “There were definitely way more people smoking.”

The study’s participants described their experiences with fentanyl, and why they’ve begun smoking it more often than injecting it. Holm said their responses represented a marked change from fentanyl users’ usual progression.

“A lot of people dabble with smoking or snorting prior to injection,” she said. “Once people inject they tend to stick with it, not only because it's the most efficient method…but also, people talk about this affinity for the process, they call it ‘being hooked on the needle.’”

The paper’s findings could have significant ramifications for San Francisco’s public-health response to the ongoing opioid epidemic. In 2023, The City experienced its deadliest year for overdose deaths since officials began collecting data in 2020. Of the 810 overdose deaths recorded last year, 80% were attributed to fentanyl .

Based on the latest report from the Office of the Chief Medical Examiner, deaths have fallen twice in the last three months , and in 2024 there have been 17 less total deaths than what it was at that time in 2023. The San Francisco Department of Public Health also recently announced a new program aimed to increase access to opioid-addiction treatment medication for unhoused people in The City.

The department declined to comment on the UCSF paper for this story.

Participants reported that increasing fears about overdosing and vein damage motivated their decision to begin smoking instead, as it makes it easier to control a dosage’s potency. They also said smoking encourages a more social atmosphere than injecting, which can help protect others from overdosing.

But there are other risks that can arise from smoking fentanyl rather than injecting, which hasn’t been studied as thoroughly. Fentanyl residue can remain in whatever smoking receptacle is being used.

A common receptacle is a type of glass “bubble” that can also often be used for smoking methamphetamines, and Holm described a scenario one of their participants shared in which a person smoking out of a bubble refused to share it with a methamphetamine user due to their concern over the residue in it.

“That was a really early lightbulb moment of, ‘Something is going on,’” Holm said. “Even the residue or the resin itself could be enough to cause a potential overdose of an opioid-naive person.”

Eisen said this was a factor that staff hadn’t previously considered for accidental overdoses, thinking those primarily happened following cross-contamination when the equipment used to make certain drugs was also used to make fentanyl.

“I hadn't actually thought the sharing of smoking equipment potentially results in people, who are going to use the same smoking equipment for meth or cocaine, may experience an overdose because there's a significant buildup of residue,” she said.

Holm added that residue can also be an issue if a smoker is consuming a drug of weaker potency after previously smoking higher-potency fentanyl. Doing so could potentially cause an overdose, she said.

Holm’s team wasn’t able to analyze the chemical composition of the residue, which resembled a black sludge, in the recently published study. She said it is something she’d like to research further going forward.

Eisen said that there isn’t just one solution for combatting this problem, but said that increasing the supply of safe smoking devices is one option.

“The original heart and spirit of harm reduction programs was…to get supplies in people's hands so they didn’t have to deal with the risks associated with sharing,” she said.

As for Holm, she said she hopes public-health agencies understand that smoking can have detrimental effects, too.

“I think this is helpful in identifying risks before this practice spreads elsewhere,” she said.