Table 1.

Inclusion/Exclusion Criteria

Inclusion	Exclusion
1. Male or female aged 21–55	1. Lifetime history of bipolar disorder or psychosis, or first-degree relative with these conditions
2. Physically healthy	2. HDRS-17 > 25 or current suicidal ideation
3. Principal DSM-5 diagnosis of OCD with illness duration ≥ 1 year and near-constant symptoms (e.g. >8 hours per day or maximum symptom-free interval <1 hour)	3. History of significant medical condition that could increase risk of cannabis side effects
4. YBOCS ≥ 16	4. Currently enrolled in or planning to begin EX/RP
5. No psychotropic medication in last 6 weeks other than SRIs, no change to SRI dose in past 6 weeks	5. Substance use disorder within the last year (including cannabis use disorder) or positive urine toxicology (for substances other than cannabis) at screening
6. Prior experience using cannabis without significant adverse effects	6. Seeking treatment for substance use
7. Capable of providing informed consent	7. Pregnant or nursing female

Abbreviations: HDRS-17, Hamilton Depression Rating Scale, 17-Item; DSM-5, Diagnostic and Statistical Manual for Psychiatric Disorders, 5^th Edition; OCD, Obsessive-Compulsive Disorder; YBOCS, Yale-Brown Obsessive Compulsive Scale; SRI, Serotonin Reuptake Inhibitor