What is Cannabis Hyperemesis Syndrome?
Cannabis hyperemesis syndrome (CHS) is a disorder of gut-brain interaction characterized by recurrent episodes of severe nausea, cyclic vomiting, and abdominal pain that occurs in chronic, heavy cannabis users and is uniquely associated with compulsive hot water bathing behavior to relieve symptoms. 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 as an antiemetic becomes pro-emetic at higher doses with chronic use 2.
Key Clinical Features
The syndrome presents with three cardinal features 1:
- Stereotypical episodic vomiting resembling cyclic vomiting syndrome (CVS), occurring 3 or more times annually
- Chronic heavy cannabis use for more than 1 year before symptom onset, typically 4 or more times per week
- Compulsive hot water bathing (prolonged hot baths or showers) to relieve symptoms - reported in 71% of patients
Typical Patient Profile
Based on systematic review of 271 cases 1:
- Mean age: 30 years
- 69% male
- Mean duration of cannabis use before symptoms: 6.6 years
- Daily cannabis use: 68% of cases
- Hot water bathing behavior: 71% of cases
Pathophysiology
The mechanism involves dysregulation of the endocannabinoid system 1:
Central mechanism: THC activates CB1 receptors in the dorsal vagal complex of the brain, which controls emesis. Chronic stimulation leads to loss of negative feedback on the hypothalamic-pituitary-adrenal axis, resulting in increased vagal nerve discharges that trigger vomiting.
Peripheral mechanism: Activation of peripheral CB1 receptors affects gastric motility, emptying, and acid secretion, contributing to gastrointestinal symptoms.
Hot water bathing: The thermoregulatory function of endocannabinoids may explain why patients compulsively seek hot water, as it activates transient receptor potential vanilloid type 1 (TRPV1) receptors that provide symptom relief 1.
Diagnostic Criteria
The following three criteria must be met for diagnosis 1:
Clinical features: Stereotypical episodic vomiting with frequency ≥3 times annually
Cannabis use patterns:
- Duration >1 year before symptom onset
- Frequency >4 times per week on average
Cannabis cessation: Resolution of symptoms after abstinence for ≥6 months, or duration equal to 3 typical vomiting cycles
Important Diagnostic Considerations
CHS should be suspected in any patient presenting with chronic nausea and vomiting who uses cannabis 1. The diagnosis is often delayed by 3-6 years due to lack of physician awareness 3, leading to extensive unnecessary testing and increased healthcare costs.
Epidemiology and Rising Prevalence
The prevalence of CHS is increasing dramatically 1:
- ED visits for CHS doubled between 2017 and 2021 in North America
- Highest prevalence in the 16-34 age group
- Rising incidence correlates with increased THC concentration in cannabis products and legalization of recreational cannabis
- An estimated 48.2 million people used cannabis in the United States in 2019
Critical caveat: CHS remains widely unrecognized by clinicians globally, resulting in frequent misdiagnosis as CVS, gastroparesis, or other functional GI disorders 4, 3.
Differential Diagnosis
After excluding life-threatening conditions (acute abdomen, bowel obstruction, mesenteric ischemia, pancreatitis, myocardial infarction), consider 1:
- Cyclic vomiting syndrome (CVS) - most similar presentation
- Cannabinoid withdrawal syndrome (CWS) - occurs with cessation, not ongoing use
- Gastroparesis
- Rumination syndrome
- Pregnancy-related nausea/vomiting
- Migraine-associated vomiting
- Functional chronic nausea and vomiting syndrome
Key distinguishing feature: While hot water bathing is reported in CVS (44% vs 19% in chronic nausea/vomiting syndrome), it is significantly more common and compulsive in CHS (71% of cases) 1.
Clinical Significance
The paradox of CHS: Patients typically report that cannabis helps relieve their symptoms, yet continued use perpetuates the syndrome 1. This creates a vicious cycle where patients increase cannabis use attempting to control symptoms, which actually worsens the condition.
The syndrome imposes substantial burden on healthcare systems through repeated ED visits, extensive diagnostic workups, and hospitalizations for severe volume depletion 2. Recognition is becoming increasingly critical as cannabis legalization expands and THC potency in commercial products continues to rise 1.