Cannabis can soothe the intestines and bladder, but too much can cause trouble.

Cannabis has been used for millennia to treat cramps and diarrhea. The basic mechanism for this effect is the presence of cannabinoid receptors (CB1 and CB2) in the smooth muscle in our intestinal wall. When activated, these receptors can decrease gut motility.

I learned this when I treated a patient who had been smoking marijuana since she arrived in San Francisco during the summer of love (1967). Day in and day out, all day, she stayed high for decades. Her use of marijuana was not the reason she sought my help. She was mainly concerned about her difficult relationship with her daughter. During our conversations, however, she revealed her unusual bowel habits. She had not had a spontaneous bowel movement for several years and relied on daily coffee enemas to evacuate her bowels. A little literature search documented the existence of cannabinoid receptors in the gut and how their stimulation inhibits the release of acetylcholine by the parasympathetic nervous system, thus reducing contractions.[1] I suggested the cause of her extreme constipation might well be due to her heavy cannabis use. The only recommendation I could make was to abstain completely from cannabis, probably for a few months. An additional benefit of abstinence might also be a new perspective on the relationship with her daughter.

She required three months in a residential treatment center before the paralyzed, flaccid smooth muscle in her intestines regained its normal tone. I assume it took that long because of how saturated her fat cells had become because of the lipid solubility of THC. It was only after her bowels returned to normal that she could talk honestly about the shame and discomfort her coffee enemas had caused her. She also found some accommodation with her daughter, although enough damage had been done to the relationship that their healing was only partial.

I was reminded of this patient when I received an email to my website from a reader asking for information about the urinary retention she had suffered because of years of cannabis. Again, I searched the literature. (I had never before perused the Indian Journal of Urology or the International Urogynecology Journal of Pelvic Floor Dysfunction!) But there it was. A study of 630 multiple sclerosis patients found that cannabis extract reduced urge incontinence episodes by 38 percent from baseline and improved overall bladder control. THC alone reduced incontinence episodes by only 33%, leading to the assumption that other cannabinoids (e.g., CBD and CBN) contributed to the slightly greater effectiveness of whole cannabis extract.[2]

The mechanism for cannabis soothing an overactive bladder appears to be like what is found in the gut. CB1 and CB2 receptors are plentiful in the smooth detrusor muscle fibers circling the bladder. Ordinarily, this muscle is relaxed to enable the bladder to fill. Emptying the bladder involves the activation of parasympathetic nerve input. The parasympathetic nervous system uses the neurotransmitter acetylcholine. THC activates the cannabinoid receptors modulating nerves where they reach the bladder, reducing the amount of acetylcholine released with each firing. This calms the bladder.[3]

The reader asked why too much cannabis can lead to a bladder that does not empty, which can become a medical emergency within a few hours. She wondered whether this was a matter of the downregulation of cannabinoid receptors by chronic cannabis use. I wish it were that simple. First, although I assume cannabinoid receptors in the gut and bladder are reduced by chronic THC use, I have not found documentation of this. Second, the endogenous cannabinoid anandamide activates more than CB1 and CB2 receptors. Anandamide also activates something called “transient receptor potential receptors,” chiefly TRPV1 receptors. This is more ruthlessly complex than we need to go into. TPRV1 receptors do not have any specific neurotransmitter connected to them. They are simply ion channels into cells that open under certain conditions such as high temperature, an acidic environment, capsaicin (the hot in chili peppers), and anandamide. The pre-synaptic inhibitory effect of anandamide is evident at low cannabinoid agonist concentrations but at higher concentrations the activation of TRPV1 counters the effect on CB1/CB2 receptors. It’s still too complicated to sort out at this point.

The bottom line is that too much of a good thing can cause trouble. Too much calming of the gut or bladder by cannabis can render them incompetent. The smooth muscle in both loses all tone. They both stop working.

This introduces the concept of moderation as the way to prevent cannabis-induced dysfunction in our gut and bladder. My next post will explore the challenges we face in achieving moderation.