Cannabis is the most commonly abused drug in the United States. Since 2008, Cannabis use has significantly increased,1 in part because of legalization for medicinal and recreational use. Cannabinoid hyperemesis syndrome (CHS) is characterized by years of daily Cannabis use, recurrent nausea, vomiting and abdominal pain, compulsive bathing for symptom relief, and symptom resolution with cessation of use.

Prompt recognition of CHS can reduce costs associated with unnecessary workups, emergency department (ED) and urgent care visits, and hospital admissions.2,3 This article provides a review of CHS with discussion of diagnostic and management considerations.

CASE REPORT Nauseated and vomiting—and stoned

Mr. M, age 24, self-presents to the ED complaining of two days of severe nausea, colicky abdominal pain, and nonbloody, nonbilious vomiting, as often as 20 times a day. His symptoms become worse with food, and he has difficulty eating and drinking because of his vomiting. Mr. M reports transient symptom relief when he takes hot showers, and has been taking more than 14 showers a day. He reports similar episodes, occurring every two or three months over the last two years, resulting in several ED visits and three hospital admissions.

Mr. M has smoked two to three joints a day for seven years; he has increased his Cannabis use in an attempt to alleviate his symptoms, but isn’t sure if doing so was helpful. He denies use of tobacco and other illicit drugs, and reports drinking one to three drinks no more than twice a month. He reports dizziness when standing, but no other symptoms. He does not take any medications, and medical and psychiatric histories are unremarkable.

Physical exam reveals a thin, uncomfortable, young man. Vital signs were significant for tachycardia and mild orthostatic hypotension. His abdomen was diffusely tender, soft, and nondistended. Urine toxicology is positive for delta-9-tetrahydrocannabinol (THC) only. Labs, including a complete blood count (CBC), basic metabolic panel, liver function tests, and lipase, are within normal limits. Prior workup included abdominal radiographs, abdominal ultrasonography, abdominal CT, and gastric biopsy; all are normal. He has mild gastritis and esophagitis on esophagogastroduodenoscopy and mildly delayed gastric emptying. HIV and hepatitis screenings are negative. Six months ago he received antibiotic therapy for Helicobacter pylori infection.

Mr. M is admitted to the hospital and seen by the psychiatric consultation service. He is treated with IV ondansetron and prochlorperazine, with little effect. He showers frequently until his symptoms begin to abate within 36 hours of stopping Cannabis use, and is discharged soon after. Psychiatric clinicians provide brief motivational interviewing while Mr. M is in the hospital, and refer him to outpatient psychiatric care and Narcotics Anonymous. Mr. M is then lost to follow up.

In 2011, 18.1 million people reported Cannabis use in the previous month; 39% reported use in 20 of the last 30 days.1 A high rate of use and a relatively low number of cases suggests that CHS is rare. However, it is likely that CHS is under-recognized and under-reported.2,4,5 CHS symptoms may be misattributed to cyclic vomiting syndrome,3 because 50% of patients diagnosed with cyclic vomiting syndrome report daily Cannabis use.6 There is no epidemiological data on the incidence or prevalence of CHS among regular Cannabis users.7

Allen and colleagues first described this syndrome in 2004.4 Since then, CHS has been documented in a growing number of case reports and reviews,2,3,5,7-13 yet it continues to be under-recognized. Many CHS patients experience delays in diagnosis—often years—resulting in prolonged suffering, and costs incurred by frequent ED and urgent care visits, hospital admissions, and unnecessary workups.2,3,7

Clinical characteristics

CHS is characterized by recurrent, hyperemetic episodes in the context of chronic, daily Cannabis use.4 The average age of onset is 25.6 years (range: 16 to 51 years).3 Ninety-five percent of CHS patients used Cannabis daily, for, on average, 9.8 years before symptom onset.3 The amount of Cannabis used, although generally high, is difficult to quantify, and has been described as heavy and hourly in units of blunts, cones, joints, bongs, etc. Patients are most likely to present during acute hyperemetic episodes, which occur in a cyclic pattern, every four to eight weeks,3 interspersed with symptom-free periods. Three phases have been described:

prodromal or pre-emetic phase

hyperemetic phase

recovery phase.4,10

Many patients report a prodromal phase, with one or two weeks of morning nausea, food aversion, preserved eating patterns, possible weight loss, and occasional vomiting. The acute, hyperemetic phase is characterized by severe nausea, frequent vomiting, abdominal pain, and compulsive bathing for temporary symptom relief. In the recovery phase, symptom improvement and resolution occur with cessation of Cannabis use.4,10 Symptom improvement can occur within 12 hours of Cannabis cessation, but can take as long as three weeks.3 Patients remain symptom-free while abstinent, but symptoms rapidly recur when they resume use.3,4