Health risks associated with smoking versus injecting fentanyl among people who use drugs in California.

Background: Given the attention, funding, and services that seek to reduce overdose mortality from fentanyl, it is important to understand whether a potential solution is for more people to switch from injecting to smoking fentanyl. As such, we set out to conduct a study to compare health and healthcare utilization outcomes associated with different modes of illicit fentanyl administration.

Methods: From January to February 2023, we recruited people who use drugs from 34 syringe services programs across California, USA (N=999) and surveyed their substance use, health outcomes, and healthcare utilization.