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04-23-12 Why should differential for patients with cyclical vomiting include marijuana use?

Question of the Week
April 23, 2012
Why should my differential for patients with cyclical vomiting/abdominal pain include marijuana use?
Recently, there have been increased reports of patients who are chronic cannabis users and who have a cyclical vomiting pattern requiring multiple visits to health care providers and emergency departments. This entity was described in 2004 by Allen, et al in Australia. (Gut 2004;53:1566-70) They had a group of patients who were chronic, daily cannabis users and had cyclical abdominal pain, nausea, vomiting that would improve by bathing in hot water. For those patients who agreed to stop their cannabis use, their symptoms improved within weeks. Some of this cohort resumed their cannabis use and had return of their cyclical vomiting and abdominal pain.  More case reports have been published describing a similar phenomenon.
The difficulty with this syndrome is that it is not intuitive, since cannabis has antiemetic effects and is associated with increased appetite (marijuana munchies). The active component of the cannabis, delta-9-tetrahydrocannabinol (THC), affects cannabinoid-1 (CB-1) receptors which are found both centrally and peripherally. Chronic, daily use of cannabis results in high body concentrations of THC. The THC stimulates the CB-1 receptor which also lives on the intestinal nerve plexus. This stimulation relaxes the lower esophageal sphincter and decreases GI motility. The explanation for the improvement with hot water bathing is even less clear and may be related to thermoregulatory functions in the hippocampal-hypothalamic-pituitary system. There are high concentrations of CB-1 receptors in the limbic system. Perhaps the heat increases the body temperature and counteracts the hypothermic effect of the cannabinoids. Our understanding of the physiology for this is not there yet.
One approach to this patient is to ask an open ended question: “What makes you feel better?” If the application of heat through bathing or hot pad is elicited, then this syndrome should be considered in the differential. The good news for the clinician is that the cyclical vomiting/abdominal pain improves if the patient will stop their cannabis use. The hard part is convincing them to quit.
This question prepared by:  Saralyn Williams, MD  Medical Toxicologist