Behavioral health challenges both contribute to and are exacerbated by homelessness. To better understand behavioral health and homelessness, we examined data from the California Statewide Study of People Experiencing Homelessness. Our latest report examines the relationship between homelessness, substance use, and mental health, providing critical insights for policymakers, program leaders, Continuum of Care leaders, and healthcare systems.

A groundbreaking UCSF BHHI study challenges common perceptions about drug use among people experiencing homelessness. Researchers found that less than half of this population regularly used drugs, with methamphetamine being the most common substance, not opioids. Many respondents wanted treatment but struggled to access it, highlighting barriers to care. The study emphasizes that homelessness and substance use are interconnected and advocates for reducing barriers to treatment and prioritizing housing solutions. "We need to reduce barriers to substance use treatment, and that includes prioritizing people’s ability to return to housing,” said BHHI faculty member Ryan Assaf, PhD, MPH, the study’s lead author.

Most people experiencing homelessness in California are not regular drug users — and for some, substance use begins or worsens after losing housing. Some use drugs to stay awake and safe, coping with the trauma and danger of life without shelter. At the same time, many who want treatment can’t get it. This paper uses data from the California Statewide Study of People Experiencing Homelessness to show a comprehensive, representative look at substance use, overdose risk, and unmet treatment needs among people experiencing homelessness in California.

The University of California, San Francisco Benioff Homelessness and Housing Initiative (BHHI) today released a report that examines the issues of homelessness and behavioral health (substance use and mental health) and makes recommendations for policymakers and practitioners.

A new UCSF BHHI study challenges common perceptions about homelessness and drug use in California, revealing that only 37% of surveyed unhoused Californians use drugs regularly, while 25% have never used them at all. Methamphetamine, not opioids, is the most commonly used drug, often as a means to stay alert while living on the streets. The study also highlights the complex relationship between addiction and homelessness—while drug use can increase the risk of losing housing, “Homelessness itself increases drug use because people use it as a coping strategy,” said Margot Kushel, MD. With homelessness on the rise and only 7% of respondents in treatment, experts stress that expanding affordable housing and accessible treatment options is crucial to addressing both crises.

Research from UCSF Benioff Homelessness and Housing Initiative reveals that most people experiencing homelessness in California are not illegal drug users—contrary to widespread public perception. These findings challenge common stereotypes and underscore the urgent need for better treatment options and housing solutions across the state. KCBS Radio news anchor Eric Thomas spoke with Margot Kushel, MD, Professor of Medicine and Chief of UCSF’s Division for Health Equity and Society, to dive deeper into the issue.

Homelessness and behavioral health issues (mental health and substance use) are intertwined. The UCSF Benioff Homelessness & Housing Initiative held a webinar about this complex bidirectional relationship, along with solutions to this crisis. Margot Kushel, MD, Claudine Sipili, Darrell Steinberg, JD, and Stephanie Welch, MSW, discussed findings from the California Statewide Study of People Experiencing Homelessness (CASPEH), highlighted key policy recommendations, and answered audience questions. Marc Dones moderated the webinar.