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Addictions, Drug & Alcohol Institute > Cannabis Education & Research Program (CERP) > Cannabis Projects

Cannabis Projects

Current projects (as of January 2026)

Clinical Resources for Cannabis Health Adverse Outcomes: Enhancing Health Care Providers’ Ability to Intervene on Cannabis Hyperemesis Syndrome and Cannabis Induced Psychosis

October 2025 – June 2027 
Status: Needs and resources’ assessment 

Patients presenting with cannabis-related adverse events (AEs) and other problems are growing more prevalent in health care settings across the U.S. and Canada, increasing the burden on providers and health systems. In a recent survey conducted among health care providers in Washington State, thirty-five percent of respondents reported seeing cannabis AEs and use-related problems frequently (at least 2-3 times a month). Severe cyclic vomiting was most common (70% reported it ever occurred) and was second to psychosis as “most serious” (33% and 34%). According to study participants, expanding access to clinical guidelines, validated tools, referral pathways, and specialized training could enhance their willingness and capacity to screen and intervene effectively on such AEs.  

In partnership with community-based organizations, clinicians, and experts, this project aims to develop, test, implement, and disseminate resources for health care providers and patients about cannabis hyperemesis syndrome (CHS) and cannabis-induced psychosis. Resources will include a set of evidence-based clinical pathways, educational materials for professionals on how to communicate with patients, and discharge and referral protocols. Resources will be developed, tested, and disseminated.

Funded by the Washington State Dedicated Cannabis Fund for research at the University of Washington.

Investigators 

Cannabis Hyperemesis Syndrome: Capturing the Narrative of People with Lived Experience

December 2025 – August 2026
Status: Data collection

Over the past decade, emergency-room doctors have increasingly treated people who have severe abdominal pain, nausea, and intense or prolonged vomiting. These patients’ common trait: chronic cannabis use.

While this condition has a name, “cannabis hyperemesis syndrome,” and a diagnostic code (R11.2, per the World Health Organization), it is still not very known to the public, clinicians, and people who consume cannabis.

This project aims to capture the experiences of people who suffered (or are still suffering) from this syndrome, as well as the testimony of experts on its causes, diagnosis, prognosis, treatment.

The result of this effort will be a video featuring interviews and testimonies to be widely disseminated among clinicians working in Washington-based health systems. The project’s goal is to increase awareness of cannabis hyperemesis syndrome and debunk myths surrounding this debilitating condition.

Funded by the Washington State Dedicated Cannabis Fund for research at the University of Washington. 

Project team

Cannabis Adverse Events in Clinical Practice: An Assessment of WA Clinicians’ Practices, Knowledge and Needs

October 2024 – February 2026
Status: Manuscript submitted for publication and under review

Patients presenting with cannabis-related adverse events (AEs) and other problems are becoming increasingly prevalent in health care settings across the U.S. and Canada, increasing the burden on providers and health systems. Understanding how healthcare providers perceive and respond to cannabis AEs can inform medical training and clinical practices, health policy, and systems-level interventions.

Methods: WA-based health care providers were invited to complete an anonymous online survey between December 2024 and March 2025 eliciting frequency and seriousness of various cannabis-related AEs, related clinical practices and procedures, knowledge and confidence.

Results: 388 valid survey responses were included in the analysis. Most respondents were Medical Doctors and worked in hospitals or primary care clinics. Thirty-five percent of respondents reported seeing cannabis AEs and use-related problems frequently (at least 2-3 times a month) in clinical practice. Severe cyclic vomiting was most common (70% reported it ever occurred) and was second to psychosis as “most serious” (33% and 34%). While most providers saw screening and intervening as important (90%), only 39.1% reported universally screening for cannabis and identified many barriers to intervening.

Conclusion: Health care providers in WA have encountered adverse events and other complications related to cannabis use, and many are concerned about their frequency and severity. Expanding access to clinical guidelines, validated tools, referral pathways, and specialized training may enhance their willingness and capacity to screen and intervene effectively.

Funded by the Washington State Legislature through ESSB 5187 (2023) and by the Washington State Dedicated Cannabis Fund for research at the University of Washington. 

Investigators

Cannabis-Related Visits Among Youth: A Seattle Children’s Practice Based Research Network Study

February 2025 to March 2026
Status: Analysis and manuscript preparation underway

Cannabis use among adolescents and young adults represents a significant public health concern, particularly with the changing legal landscape and increased availability of cannabis products. Cannabis use during adolescence has been associated with several adverse health outcomes including higher rates of associated mental health disorders, worsened academic performance, and increased risk of development of substance use disorders.  

Pediatric healthcare settings are increasingly encountering cannabis-related visits yet comprehensive data characterizing these encounters within primary care networks remains limited. Previous studies have focused primarily on emergency department visits or hospitalizations. However, there is limited data on the spectrum of cannabis related concerns that present to primary care, trends over time, and factors associated with presentation.  

To address this gap, CERP has partnered with Dr. Alexis Ball from UW Pediatrics in a study that seeks to characterize cannabis-related visits among youth (ages 12-21) to clinics participating within Seattle Children’s Practice Based Research Network from 2015-2024.

Funded by the Washington State Legislature through ESSB 5187 (2023) and by the Washington State Dedicated Cannabis Fund for research at the University of Washington. 

Investigators:

Cannabis Adverse Events among Medicaid Recipients in WA State 

July 2024 – June 2027
Status: Contract under negotiation

With cannabis legalization in WA State has come an increase in cannabis use prevalence, daily use, and THC concentration of available products. These changes have been linked to corresponding health care utilization due to cannabis-related adverse outcomes in Colorado and Canada. These outcomes range from acute events such as panic attacks, cannabis-induced psychosis, vomiting and cardiac events to conditions that typically develop over time, such as cannabis hyperemesis syndrome and cannabis use disorder. Little is known about health care utilization due to cannabis-related adverse outcomes in WA State, the type of events seen most frequently, and how and if they are being recorded in medical records and claims.  

This project will use statewide Medicaid claims data to describe cannabis-related adverse outcomes among Medicaid patients in primary care, hospitals, and emergency departments across the state. Descriptive analyses will (aim 1) identify the prevalence of specific types of cannabis-related events, (aim 2) who is most affected (age, race/ethnicity, gender, county, and other diagnoses), and (aim 3) the healthcare settings most commonly responding to these events.

Funded by the Washington State Dedicated Cannabis Fund for research at the University of Washington. 

Investigators

Reporting THC Content in Cannabis Products in Legal Markets: An international Multidisciplinary Delphi Consensus Study 

Status: Manuscript submitted for publication and under review.

In countries where cannabis products are legal, the THC content on licensed cannabis products is inconsistently reported (e.g., % percentage or concentration, milligrams). This project aim to establish guidelines on how to report the amount of Delta-9-Tetrahydrocannabinol (THC) consistently and accurately across all cannabis products. To achieve this goal, the project will utilize a Delphi methodology with a multidisciplinary and international expert to achieve consensus on how to report THC content for consumers (e.g., product labelling and packaging) across all cannabis products (e.g., medical/non-medical, administered via distinct modes).

Steering Committee members

Completed Projects

2026

People Living with Psychosis are Disproportionately Affected by Cannabis Adverse Events: A Study in WA State, USA

Background: Cannabis use has been shown to negatively impact the management and prognosis of psychotic disorders. Little is known about the broader health impacts of cannabis use in this population. This study compares cannabis-related negative health outcomes among individuals with a diagnosis of a psychotic disorder to those with other mental health (MH) diagnoses or no MH diagnosis. 

Methods: Data came from International Cannabis Policy Study (2020-2023). Respondents were 4,144 Washington State individuals aged 16–65, who consumed cannabis in the last 12 months. Three groups were compared for cannabis use negative health events: (lifetime diagnoses of psychotic disorders, other MH and no MH diagnoses). Logistic regressions were used in the analysis. 

Results: People with psychotic disorders were more likely to report adverse events from their cannabis use and to pursue medical attention than consumers with other MH or no MH diagnoses (p<.001.) They had higher likelihood of nausea/vomiting (2.2 to 3.7 times as likely), heart or blood pressure problems (3.3 to 8.6), fainting (2.7 to 4.9), acute psychosis or hallucinations (5.4 to 6.2), flashbacks (4.3 to 11.5), Cannabis Hyperemesis Syndrome (3.1 to 7) and positive screening for high-risk cannabis use (3.4 to 6.9) than consumers with other MH or no MH diagnoses. 

Conclusion: Individuals with psychotic disorder experience more adverse health events from cannabis, including events not associated with exacerbation of their disorders. These findings highlight the need to develop focused clinical interventions and awareness campaigns to address elevated risks of cannabis use among this vulnerable population.  

Funded by the Washington State Legislature through ESSB 5187 (2023) and by the Washington State Dedicated Cannabis Fund for research at the University of Washington.  

Investigators 

Project Results: Carlini BH, Williams JR, Garrett SB, Hammond D. People with psychotic disorders are the most vulnerable to cannabis adverse health outcomes: a study in WA State, USA. Community Ment Health J. Published online January 16, 2026. doi:10.1007/s10597-025-01579-1 

2025

2024

2023 and earlier