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Toxicology Rounds: The Anti-Munchies: Cannabinoid Hyperemesis Syndrome

Gussow, Leon MD

doi: 10.1097/01.EEM.0000407853.39467.05
Toxicology Rounds


Narcotic bowel syndrome is a counterintuitive and paradoxical medical condition. A patient who presents with chronic abdominal pain and no specific diagnosis despite extensive workups could actually be suffering from gastrointestinal side effects brought on by narcotic medications prescribed to control the pain. As I discussed in my last column, the pain resolves when the patient is weaned off narcotics. (“Chronic Abdominal Pain? Think Narcotic Bowel Syndrome,” EMN 2011;33[10]:39;

Yet another drug-related condition can cause mysterious, severe gastrointestinal symptoms — cannabinoid hyperemesis syndrome. As with narcotic bowel syndrome, this syndrome is not widely known; in fact, I hadn't heard of it until several case series appeared in the medical literature recently. Australian researchers described the first series in 2004, reviewing nine patients whose distinctive presentation included chronic cannabis use, cyclic vomiting, and compulsive bathing.

The nine cases described in this paper shared the same clinical characteristics:

  • Cyclical episodes of profuse vomiting, occurring every few weeks or months. The vomiting was often accompanied by colicky abdominal pain, diaphoresis, and polydipsia. Symptoms had typically continued for many years, requiring multiple hospital admissions and extensive GI workups that never established an alternate diagnosis. Vomiting tended to be resistant to treatment with antiemetics.
  • A history of regular cannabis use, usually over a period of at least several years predating the onset of cyclic vomiting.
  • Relief of symptoms when the patient took a hot bath or shower. This resulted in compulsive bathing behavior, a striking characteristic that was the most unusual manifestation of this syndrome, and is considered pathognomonic.
  • Vomiting episodes ceased when patients refrained from cannabis use, and symptoms returned if cannabis use was resumed.

The authors note that the compulsion to take multiple and prolonged hot baths and showers is an adaptive learned behavior, and does not constitute evidence of neurosis or obsessive-compulsive disorder. Patients simply discover that exposure to hot water helps relieve vomiting and abdominal pain. It follows that those who present during the initial episodes of cyclic vomiting in cannabinoid hyperemesis syndrome might not have realized this connection, and might not exhibit this distinctive feature of the syndrome. The diagnosis is based on history and clinical presentation after other causes of cyclic vomiting and abdominal pain have been ruled out.

The mechanism by which cannabis, a product commonly regarded as an antiemetic, causes cyclic vomiting in some persons after prolonged use is not known. The authors suggest several possibilities. Because cannabinoids are lipophilic and have long half-lives, they may accumulate with chronic heavy use to the point where they start to exert a paradoxical effect. This may be related to their well-described ability to delay gastric emptying and decrease gastrointestinal motility. Any of the more than 60 different compounds contained in raw marijuana might directly affect the limbic system or hypothalamus in ways that have not yet been defined.

The authors of this recent paper identified another 22 patients with cannabinoid hyperemesis syndrome after the Allen paper in 2004, bringing the total number of cases in the medical literature to 31. They point out that the diagnosis was typically delayed for a number of years after onset of symptoms (mean 4.5 years, range 0-29 years).

The compulsive bathing behaviors exhibited by these 22 patients were extreme. One patient reported spending all day in the bathtub for 300 days one year. (I would be interested in seeing his heating bill!) He came to the hospital when his hot water heater finally broke down.

Of course, it is crucial to rule out significant underlying acute medical and surgical conditions — such as pancreatitis — when a patient presents with nausea, vomiting, and abdominal pain. Once this is done, the differential diagnosis of cyclic vomiting is somewhat limited. (See table.) If the patient has a history of chronic cannabis abuse, and finds symptomatic relief by taking hot baths or showers — voilà! Treatment consists of hydration and providing the patient with resources to help him refrain from cannabis exposure in the future.

One problem: most cannabis users are well aware that the drug is used medically as an antiemetic, and may resist the notion that it could be responsible for their repeated bouts of nausea and vomiting. In this case, referring the patient to discussions of cannabinoid hyperemesis syndrome on the Internet may be helpful. Unfortunately, as of this writing, there don't seem to be any such discussions of the topic on web sites frequently visited by drug users, such as Erowid and Bluelight. There is, however, a good entry about it on Wikipedia. (

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Dr. Gussowis a voluntary attending physician at the John H. Stroger Hospital of Cook County in Chicago (formerly Cook County Hospital), an assistant professor of emergency medicine at Rush Medical College, and a consultant to the Illinois Poison Center. He is also the editor of his own blog, The Poison Review (

Differential Diagnosis of Cyclic Vomiting

Differential Diagnosis of Cyclic Vomiting

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In Brief

Warmed Anesthetics Lessen Injection Pain

Warming local anesthetics leads to less pain during injection, according to a study completed at the Leslie Dan Faculty of Pharmacy in Toronto.

The study sought to analyze the effect of warming local anesthetics in adults and children undergoing local anesthetic infiltration into intradermal or subcutaneous tissue. The researchers included studies with randomized or pseudo–randomized designs and healthy subjects receiving subcutaneous or intradermal injection of local anesthetics that were warmed to body temperature or kept at room temperature. The outcome was self-reported pain. Some 831 patients were included in a meta-analysis, which showed a mean difference of 11 mm on a 100-mm scale in favor of warming local anesthetics.

© 2011 Lippincott Williams & Wilkins, Inc.