Table 1.

Summary of observational studies and clinical trials of cannabis in inflammatory bowel disease.

Study	Year	Country	Study design	IBD	Number	Product	Safety	Findings
Naftali 67	2011	Israel	Retrospective Observational	CD	30	Oral or Inhaled Cannabis	Not reported	Improvement in disease activity (⩾4 point reduction in HBI score). A reduction in need for other medications
Lahat 72	2012	Israel	Prospective Observational	CD and UC	13	50 g dry processed cigarettes per month	Not reported	Improvement in quality of life scores and disease activity indices (HBI)
Naftali 68	2013	Israel	Prospective Placebo Controlled Trial	CD	21	Cigarettes containing 115 mg THC twice daily	No difference in adverse effects between groups	No difference in clinical remission. (CDAI score <150) Benefits in clinical response (decrease in CDAI of >100) and steroid use. Improvement in symptoms (sleep and appetite)
Naftali 69	2017	Israel	Prospective Placebo Controlled Trial	CD	19	Oral CBD 10 mg twice daily	No difference in adverse effects between groups	No beneficial effects in IBD. (Decrease in CDAI >70) Safe and well tolerated
Irving 70	2018	United Kingdom	Double Blind placebo controlled, Parallel-group	UC	60	Oral capsule containing 50 mg CBD rich botanical extract taken twice daily	Higher mild- moderate adverse effects in treatment group (90% versus 48% in placebo)	Not effective in inducing remission. (Mayo score of ⩽2 with no sub score >1) Improved quality of life and global impression of change scores.

CBD, cannabidiol; CD, Crohn’s disease; CDAI, Crohn’s Disease Activity Index; HBI, Harvey-Bradshaw Index; IBD, inflammatory bowel diseases; THC, Δ⁹-tetrahydrocannabinol; UC, ulcerative colitis.