Two authors independently screened search results, extracted data and assessed bias using the Cochrane risk of bias tool. The primary outcomes were clinical remission and relapse. Remission is commonly defined as a Crohn’s disease activity index (CDAI) of < 150. Relapse is defined as a CDAI > 150. Secondary outcomes included clinical response, endoscopic remission, endoscopic improvement, histological improvement, quality of life, C-reactive protein (CRP) and fecal calprotectin measurements, adverse events (AEs), serious AEs, withdrawal due to AEs, and cannabis dependence and withdrawal effects. We calculated the risk ratio (RR) and corresponding 95% confidence interval (95% CI) for dichotomous outcomes. For continuous outcomes, we calculated the mean difference (MD) and 95% CI. Data were combined for analysis when the interventions, patient groups and outcomes were sufficiently similar (determined by consensus). Data were analyzed on an intention-to-treat basis and the overall certainty of the evidence supporting the outcomes was evaluated using the GRADE criteria.
We searched MEDLINE, Embase, AMED, PsychINFO, the Cochrane IBD Group Specialized Register, CENTRAL, ClinicalTrials.Gov, and the European Clinical Trials Register up to 17 October 2018. We searched conference abstracts, references and we also contacted researchers in this field for upcoming publications.
One small study (N = 22) compared cannabis oil (5% cannabidiol) to placebo oil in people with active CD. This study was rated as high risk of bias for other bias (cannabis participants were more likely than placebo participants to be smokers). There was no difference in clinical remission rates. Forty per cent (4/10) of cannabis oil participants achieved remission at 8 weeks compared to 33% (3/9) of the placebo participants (RR 1.20, 95% CI 0.36 to 3.97; very low certainty evidence). There was no difference in the proportion of participants who had a serious adverse event. Ten per cent (1/10) of participants in the cannabis oil group had a serious adverse event compared to 11% (1/9) of placebo participants (RR 0.90, 95% CI 0.07 to 12.38, very low certainty evidence). Both serious AEs were worsening Crohn’s disease that required rescue intervention. This study did not report on clinical response, CRP, quality of life or withdrawal due to AEs.
What did the researchers investigate?
Cannabis is a widely used drug which acts on the endocannabinoid system. Cannabis contains multiple components called cannabinoids. The use of cannabis and cannabis oil containing specific cannabinoids produces mental and physical effects such as altered sensory perception and euphoria when consumed. Some cannabinoids, such as cannabidiol, do not have a psychoactive effect. Cannabis and cannabidiol have some anti-inflammatory properties that might help people with Crohn’s disease.
The researchers extensively searched the literature up to 17 October 2018 and found three studies (93 participants) that met the inclusion criteria. One ongoing study was also identified. All of the studies were small in size and had some quality issues. One small study (21 participants) compared eight weeks of treatment with cannabis cigarettes containing 115 mg of D9-tetrahydrocannabinol (THC) to placebo cigarettes containing cannabis with the THC removed in participants with active Crohn’s disease who had failed at least one medical treatment. Although no difference in clinical remission rates was observed, more participants in the cannabis group had improvement in their Crohn’s disease symptoms than participants in the placebo group. More side effects were observed in the cannabis cigarette group compared to placebo. These side effects were considered to be mild in nature and included sleepiness, nausea, difficulty with concentration, memory loss, confusion and dizziness. Participants in the cannabis cigarette group reported improvements in pain, appetite and satisfaction with treatment.
What are Cannabis and Cannabinoids?
Your doctor may have other ideas about ways to help you feel better. For now, if you’re set on trying it, Kinnucan suggests starting with the lowest THC concentration and going from there to limit potential side effects. Work with a medicinal pharmacy that may have some more advice about what’s available.
The answer is no, she says. There’s no objective improvement in inflammation.
“If we followed patients longer, we might see some benefit,” Kinnucan says. “Maybe 8 weeks isn’t long enough.”
What to Consider
More research is needed in more people with Crohn’s disease, and there are studies ongoing. One reason it’s complicated is that cannabis comes in many varieties. The plant has two main active ingredients: THC (short for delta-9 tetrahydrocannabinol) and CBD (short for cannabidiol). It’s the THC in marijuana that gives you a high. The CBD products you can buy usually come from hemp and shouldn’t have much if any THC. We need more time to study the various compounds found in cannabis.
Jami Kinnucan, MD, gastroenterologist, University of Michigan.
The evidence available — while not convincing — doesn’t rule out the possibility that cannabis might help some people with Crohn’s. Kinnucan says one reason studies so far may not show a benefit is that they might not use the best cannabis formulations. There’s some experimental evidence that cannabinoids can help with inflammation. But, she says, it might take a more targeted approach to see those benefits in people with IBD. The existing studies also have been small and short-term.
Mayo Clinic: “Medical Marijuana.”