Psilocybin in the Treatment of Cannabis Use Disorder: A-Proof-of-Concept Study

An 8-week Phase 2 Clinical Trial to Evaluate the Safety, Tolerability and Efficacy of Psilocybin-assisted-psychotherapy in Adults With Cannabis Use Disorder: A Proof-of-Concept Study

Psilocybin in the Treatment of Cannabis Use Disorder: A-Proof-of-Concept Study (NCT06225232) is a Phase 2 interventional studying Cannabis Use Disorder, Moderate and Cannabis Use Disorder, Severe, sponsored by McMaster University. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

Cannabis is the most commonly used psychoactive substance in Canada (Lowry \& Corsi, 2020). A sub-group of cannabis users develop a condition known as Cannabis Use Disorder (CUD), which is defined as a regular pattern of cannabis use that causes performance difficulty at work, school and relationships (Hasin et al., 2013). A review of current treatments available for CUD indicate the lack of a pharmacological and psychological treatment with high success rates, which highlights the importance of exploring potential psychosocial interventions for the treatment of CUD. Given the evidence of psilocybin's therapeutic potential in the treatment of substance use disorders (de Veen et al., 2017), we aim to conduct a study using psilocybin-assisted-psychotherapy in the treatment of CUD. The study aims to evaluate the feasibility, safety, tolerability and potential therapeutic effect of 2 doses \[25 mg\] of psilocybin administered as part of an 8-week Motivational Enhancement Therapy (MET) and supportive therapy. This trial will be the first to evaluate the potential treatment effects of psilocybin on symptoms of CUD.

What Stage of Research Is This?

Phase 2 trials evaluate whether a treatment actually works against Cannabis Use Disorder, Moderate and continue monitoring side effects. Phase 2 enrolls larger groups (typically 100–300 patients) and produces the first real efficacy signal. A successful Phase 2 readout is what unlocks the much larger Phase 3 confirmatory trials needed for FDA approval.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

With a target enrollment of 16 participants, this is a small study — typical of early-phase research, rare-disease trials, or pilot studies designed to generate preliminary signal before a larger study is launched.

Who May Be Eligible (Plain English)

Who May Qualify: 1. Signed willing to sign a consent form Form. 2. Able to show documentation of identity. 3. Fluent in speaking and reading English and able to complete rating scales and assessments. 4. Between the ages of 18 to 65. 5. At Screening, meet criteria for CUD diagnosis of at least moderate severity as per the MINI Plus 6. Expressed a wish to reduce or stop cannabis use. 7. Medically healthy based on physician review of CBC, electrolytes, liver function test, kidney function tests and ECG. 8. Has a stable residence for the duration of the study. 9. Agree to comply with the protocol requirements set out by the study. 10. Consent to providing regular check-ins and follow-up regarding any medical conditions, procedures and adverse events. 11. If of child-bearing potential, female participants must agree to use an adequate birth control method (IUD, injected or implanted hormonal methods, abstinence, vasectomy of the partner/partners, or double barrier contraception i.e. condoms plus diaphragm, or diaphragm plus spermicide) for the duration of the study. Male participants should agree to using condoms with spermicide throughout the trial in addition to the use of an adequate contraceptive by their partner of childbearing potential. 12. Following discharge from the dosing sessions, agree to have another individual accompany them home from the study site and stay with them overnight. Who Should NOT Join This Trial: 1. Meet DSM-5 criteria for lifetime history of bipolar disorder, schizophrenia, or other psychotic disorders, personality disorders, delirium, dementia and amnesic and other cognitive disorders, or are in a current agitated state. 2. Have first-degree biological relatives (parents or full siblings) with past or present history of schizophrenia, bipolar disorder and any other psychosis. 3. Meet DSM-5 criteria for panic disorder or seizure disorders. ...See full criteria on ClinicalTrials.gov Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

Inclusion Criteria: 1. Signed Informed Consent Form. 2. Able to show documentation of identity. 3. Fluent in speaking and reading English and able to complete rating scales and assessments. 4. Between the ages of 18 to 65. 5. At Screening, meet criteria for CUD diagnosis of at least moderate severity as per the MINI Plus 6. Expressed a wish to reduce or stop cannabis use. 7. Medically healthy based on physician review of CBC, electrolytes, liver function test, kidney function tests and ECG. 8. Has a stable residence for the duration of the study. 9. Agree to comply with the protocol requirements set out by the study. 10. Consent to providing regular check-ins and follow-up regarding any medical conditions, procedures and adverse events. 11. If of child-bearing potential, female participants must agree to use an adequate birth control method (IUD, injected or implanted hormonal methods, abstinence, vasectomy of the partner/partners, or double barrier contraception i.e. condoms plus diaphragm, or diaphragm plus spermicide) for the duration of the study. Male participants should agree to using condoms with spermicide throughout the trial in addition to the use of an adequate contraceptive by their partner of childbearing potential. 12. Following discharge from the dosing sessions, agree to have another individual accompany them home from the study site and stay with them overnight. Exclusion Criteria: 1. Meet DSM-5 criteria for lifetime history of bipolar disorder, schizophrenia, or other psychotic disorders, personality disorders, delirium, dementia and amnesic and other cognitive disorders, or are in a current agitated state. 2. Have first-degree biological relatives (parents or full siblings) with past or present history of schizophrenia, bipolar disorder and any other psychosis. 3. Meet DSM-5 criteria for panic disorder or seizure disorders. 4. Meet DSM-5 criteria for dependence of any substance other than cannabis or tobacco in the past 6 months. 5. Positive urine drug screen for substances tested with the exception of cannabis 6. History of serotonergic psychedelic use in the past year and over 5 times of lifetime use (psilocybin, LSD, Ayahuasca, mescaline, DMT). 7. Current treatment with psychotropic agents including stimulants, anti-psychotic agents, benzodiazepines and tri-cyclic anti-depressants. Concurrent treatment with Selective Serotonin Reuptake Inhibitors and Serotonin Noradrenalin Reuptake Inhibitors will be allowed, provided the dose has been stable for 4 weeks and remains stable during the study. 8. History of cardiovascular diseases or uncontrolled hypertension that is not successfully treated or any other medical condition that might pose a risk to the participant in the opinion of the study physician. 9. Are receiving concurrent psychotherapy for CUD. 10. Are reasonably judged to present a serious suicide risk as determined by Columbia Suicide Severity Rating Scale or expressed homicide risk, who have enacted suicidal behaviors within 6 months prior to intake, or w ho are likely to require psychiatric hospitalization during the study. 11. Participants of childbearing potential with a positive pregnancy test at screening or prior to dosing sessions, or are pregnant, breast feeding, and who are not using an acceptable means of birth control for the duration of the study. 12. Are unable to fully understand the potential risks and benefits of the study and give informed consent. 13. Are currently or planning on participating in other interventional clinical trials during this study.

Treatments Being Tested

DRUG

Psilocybin combined with Psychotherapy

The intervention consists of a 9-week treatment protocol that is based on supportive psychotherapy and Motivational Enhancement Therapy. Overall, the therapy course includes 8 motivational enhancement therapy sessions and two experimental drug sessions.

Locations (1)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

MacAnxiety Research Centre

Hamilton, Ontario, Canada

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT06225232), the sponsor (McMaster University), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT06225232 clinical trial studying?

Who can participate in NCT06225232?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT06225232?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT06225232. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT06225232. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-06-07 · Data from ClinicalTrials.gov.