What is Cannabinoid Hyperemesis Syndrome (CHS)?
CHS is a disorder of gut-brain interaction characterized by cyclic episodes of severe nausea, vomiting, and abdominal pain that occurs in chronic cannabis users, typically after more than 1 year of frequent use (≥4 times per week), and resolves only with sustained cannabis cessation. 1
Clinical Definition and Classification
CHS has been formally recognized in the Rome IV classification of functional gastrointestinal disorders since 2016 as a brain-gut axis disorder. 1 The syndrome represents a paradoxical response to cannabis, where a substance typically used for its antiemetic properties instead triggers severe, recurrent vomiting episodes. 1
Pathophysiology
The mechanism involves dysregulation of the endocannabinoid system through chronic overstimulation of CB1 receptors:
- THC (Δ9-tetrahydrocannabinol) activates CB1 receptors densely distributed in the dorsal vagal complex of the brain, which controls emesis. 1
- Chronic stimulation disrupts the negative feedback on the hypothalamic-pituitary-adrenal axis, leading to increased vagal nerve discharges that trigger vomiting. 1
- Peripheral CB1 receptor activation affects gastric motility, emptying, and acid secretion. 1
- THC also binds to transient receptor potential vanilloid type 1 (TRPV1) channels, affecting vagus nerve and gut function. 1
Diagnostic Criteria
Three essential elements must be present for diagnosis: 1
1. Clinical Features
- Stereotypical episodic vomiting resembling cyclic vomiting syndrome (CVS)
- Frequency of 3 or more episodes annually 1
- Cyclic pattern with symptom-free intervals between episodes 1
2. Cannabis Use Patterns
- Duration of cannabis use more than 1 year before symptom onset 1
- Frequency of use more than 4 times per week on average 1
- Typically daily use (reported in 68% of cases) 1
3. Cannabis Cessation Response
- Resolution of symptoms after abstinence from cannabis for at least 6 months 1
- Alternative criterion: abstinence equal to the total duration of 3 typical vomiting cycles in that patient 1
Characteristic Clinical Features
Hallmark Symptom: Hot Water Bathing
- Compulsive hot water bathing or showering is reported in 71% of CHS patients. 1
- While not pathognomonic (also occurs in CVS), it is commonly considered an indicator of CHS among adults with cyclic vomiting. 1
- Patients may spend hours in hot showers seeking symptom relief. 1
Demographics
Based on a systematic review of 271 cases: 1
- Mean age: 30 years
- Male predominance: 69%
- Mean duration of cannabis use before symptom onset: 6.6 years
- Daily use: 68% of patients
Recent Epidemiological Trends
- CHS prevalence in US emergency departments increased from 4.4 per 100,000 visits in 2016 to 33.1 per 100,000 in Q2 2020, remaining elevated at 22.3 per 100,000 in 2022. 2
- Highest risk occurs in ages 18-25 years (RRR 3.59) and 26-35 years (RRR 2.26). 2
- The sharp increase during the COVID-19 pandemic suggests correlation with increased cannabis access and use. 2
Clinical Presentation
Suspect CHS in any patient with chronic nausea and vomiting who uses cannabis regularly. 1
Symptom Pattern
- Cyclic episodes of severe nausea and vomiting 1
- Abdominal pain (often epigastric) 1
- Symptoms persist for median duration of 7 days following an ED visit 3
- Symptom-free intervals between episodes 1
Important Clinical Pitfall
CHS is frequently misdiagnosed, resulting in extensive unnecessary investigations and delayed treatment. 4 Standard antiemetics like ondansetron typically fail to provide relief, which should raise suspicion for CHS rather than other causes of vomiting. 5
Differential Diagnosis
In the emergency department, immediately exclude life-threatening conditions: 1
- Acute abdomen
- Bowel obstruction
- Mesenteric ischemia
- Pancreatitis
- Myocardial infarction
In the outpatient setting after excluding structural abnormalities, consider: 1
- Cyclic vomiting syndrome (CVS) without cannabis use
- Rumination syndrome
- Gastroparesis
- Pregnancy-related nausea/vomiting
- Migraine-associated vomiting
- Functional chronic nausea and vomiting syndrome
- Cannabinoid withdrawal syndrome (CWS) - occurs with cessation rather than ongoing use 1
Management Approach
Acute/Emergency Department Treatment
Avoid opioids - they worsen nausea and carry high addiction risk. 1
Evidence-supported acute therapies include: 1
- Haloperidol - dopamine antagonist with demonstrated efficacy 6, 7
- Droperidol - dopamine antagonist 7
- Topical capsaicin (0.1% cream) - activates TRPV1 receptors, may improve symptoms 1
- Benzodiazepines 1
- Promethazine 1
- Olanzapine 1
- Ondansetron (though often ineffective) 1
Note: Evidence supporting these treatments is limited to case series and small clinical trials. 1
Long-Term Management
The mainstay of long-term therapy consists of: 1
Cannabis cessation counseling - the definitive cure 7
Tricyclic antidepressants (amitriptyline):
Topical capsaicin (0.1%) cream - applied with close monitoring 1
Psychosocial Considerations
- Co-management with psychology or psychiatry is helpful for patients with poor response to standard therapies or extensive psychiatric comorbidity. 1
- Anxiety and depression are very common associated conditions. 1
- Many patients remain uncertain about the role of cannabis despite recurrent episodes, attributing symptoms to food, alcohol, stress, or other GI disorders. 1
- Combining evidence-based psychosocial interventions with pharmacology may be necessary for successful long-term management. 1
Clinical Course After ED Visit
- 25% of patients have recurrent ED visits for cyclic vomiting within 3 months. 3
- Most patients reduce cannabis use immediately after ED visit but return to pre-ED use patterns within days. 3
- Persistent symptoms continue for median 7 days post-ED visit, though most patients manage symptoms at home. 3
- Over 40% of patients may eventually stop all treatments for CHS, but recidivism rates are high. 1
Unproven Strategies
The following lack scientific validation: 1
- Switching to lower THC/higher CBD formulations
- Using edible forms instead of smoking
- Avoiding THC concentrates