Marijuana and Colonic Transit Time
Direct Effect on Colonic Transit
Marijuana and cannabinoid agents slow colonic transit time through activation of CB1 receptors in the enteric nervous system, which inhibits colonic tone and phasic pressure activity. 1, 2
Mechanism of Action
- Cannabinoids activate CB1 receptors located on neurons in the myenteric plexus, which reduces excitatory enteric transmission (primarily cholinergic) throughout the gastrointestinal tract 2
- The non-selective cannabinoid agonist dronabinol retards gastric emptying and inhibits colonic tone and phasic pressure activity 1
- Activation of prejunctional CB1 receptors reduces gastrointestinal transit in both animal models and human studies 2, 3
- In the GI tract, the activated endocannabinoid system reduces gut motility, intestinal secretion, and epithelial permeability 4
Clinical Implications for Patients with Pre-existing GI Conditions
In patients with inflammatory bowel disease (IBD), cannabinoids may provide dual effects: reducing inflammation while simultaneously slowing colonic transit. 4, 5
- Clinical studies in IBD demonstrate that subjects benefit from cannabis consumption through reduction of IBD-inflammation, though the impact on transit time must be considered 5
- In pathophysiological inflammatory states, both CB1 and CB2 receptors could reduce the increase of intestinal motility induced by inflammatory stimuli 2
- The endocannabinoid system contributes to gut homeostasis and can modulate inflammatory responses in the GI tract 5
Critical Considerations for Constipation Patients
Patients with pre-existing slow transit constipation should avoid marijuana, as decreased enteric FAAH activity is already associated with colonic inertia in slow transit constipation, and cannabinoids would further impair transit. 1
- Decreased enteric fatty acid amide hydrolase (FAAH) activity is associated with colonic inertia in slow transit constipation 1
- Cannabinoid mechanisms result in human and animal models of gastrointestinal and colonic dysmotility 1
- Randomized clinical trials confirm that cannabinoids reduce gastrointestinal motility 2
Potential Therapeutic Applications
For patients with diarrhea-predominant conditions or rapid transit, cannabinoid modulation may theoretically provide benefit by slowing excessive motility, though high-quality controlled studies are lacking. 2, 5
- Modulation of the gut endogenous cannabinoid system may provide a useful therapeutic target for disorders of gastrointestinal motility 2
- Cannabis has been known for centuries to be beneficial in diarrhea, though modern evidence remains limited 2
- Experimental therapies are focused on inhibition of DAGLα to normalize colonic transit 1
Common Pitfalls
- Do not assume marijuana will help all GI symptoms—in patients with constipation or slow transit, it will worsen the condition by further slowing colonic transit 1, 2
- Be aware that central and peripheral side effects may occur upon acute and chronic cannabinoid administration 3
- Recognize that cannabinoid hyperemesis syndrome can develop with chronic use, characterized by cyclic vomiting, nausea, and abdominal pain 6
- Over-activation of cannabis receptors CB1 and CB2 can lead to changes in commensal gut flora, potentially altering disease severity 5