Concerns Over Cannabis and Mental Health in Washington

SEATTLE — Over ten years after the legalization of recreational cannabis in Washington, a recent survey indicates that many healthcare professionals are increasingly worried about its potential mental health risks. In fact, some are actively treating patients for health issues related to cannabis use.

The findings, published in the Substance Use & Addiction Journal, stem from a 20-question survey that involved 388 doctors, nurses, and other healthcare workers in Washington, conducted between December 2024 and March 2025.

The survey aimed to understand clinicians’ experiences treating patients with cannabis-related health problems since the drug became legal for recreational use in 2012.

Results showed that more than half of the respondents expressed significant concern regarding the mental health repercussions of cannabis. Nearly 20% reported encountering patients with adverse health events related to cannabis two to three times each month.

“Healthcare providers are noticing, and are understandably worried about, cannabis adverse events,” noted Beatriz Carlini, the lead author and a research associate professor of psychiatry and behavioral sciences at the University of Washington. She mentioned that interestingly, there hasn’t been much prior research addressing clinicians’ experiences with cannabis-related conditions in the U.S.

Four primary conditions that arose as notable concerns from the survey included:

• 70% of clinicians reported treating patients for cannabis hyperemesis syndrome, which involves repeated bouts of nausea and severe vomiting, often leading to dehydration and extended emergency room visits.
• 65% identified cases of cannabis-use disorder, indicating signs of addiction or dependency.
• 63% noted patients dealing with anxiety related to cannabis consumption.
• 53% reported cases of psychosis or hallucinations attributed to cannabis, with 34% considering these the most serious adverse events associated with its use.

When asked about their knowledge of cannabis-related clinical issues, most respondents categorized themselves as “moderately” knowledgeable, compared to other levels like “extremely/very” or “slightly/not at all.”

The survey also highlighted gaps in training; approximately 66% reported having minimal or no understanding of how cannabis interacts with other medications, and nearly 43% admitted to limited knowledge regarding cannabis-induced psychoses. A significant 75% expressed interest in receiving additional training on how to screen for cannabis use and manage associated health risks.

Respondents identified systemic barriers hindering effective treatment of cannabis-related conditions. More than 80% stated they would be more inclined to screen and intervene if clear treatment protocols and more referral options were available.

Carlini emphasized that the lack of providers specialized in cannabis-related care is a persistent issue, especially as those working in substance-use treatment are currently overwhelmed with patients facing opioid and methamphetamine issues, along with ongoing alcohol-related challenges.

While the study did not assess whether cannabis-related adverse health effects are increasing in Washington, Carlini pointed out that literature from other regions suggests that this is indeed a possibility.