Authors: Tom Bannister / Codes: GC4, GP1, GP9, MHC1, SLO1 / Published: 17/06/2024

Scope / Reason for development

Cannabinoid Hyperemesis Syndrome (CHS) is an episodic syndrome of cyclical vomiting in the context of the prolonged use of cannabis. Vomiting episodes are not necessarily temporally related to increased cannabis use, and patients may find that cannabis use during an episode actually improves their symptoms.

CHS is unlikely to be definitively diagnosed in the Emergency Department (ED) due to the current diagnostic criteria. The essential prerequisite for a CHS diagnosis is the long-term use of cannabinoids. There are no laboratory or radiographic investigations that can be used to diagnose CHS.

Patients presenting with CHS often experience a delay to diagnosis. They will typically have repeated visits to emergency departments, several hospital admissions and often describe poor symptom control with standard therapies, such as antiemetic medications.

Summary of Recommendations

  1. A diagnosis of Cannabinoid Hyperemesis Syndrome (CHS) should be considered in presentations of nausea and vomiting with a cyclical pattern and where there is associated cannabis use.
  2. Patients should be encouraged to disclose their cannabis use and be reassured that this disclosure will not affect them adversely and will remain confidential. Care should be taken to ensure that patients do not feel stigmatised for their use of cannabis.
  3. Failure of standard antiemetic therapy to improve symptoms should lead to consideration of the use of haloperidol or capsaicin.
  4. Patients may struggle to accept a diagnosis of CHS for a variety of reasons. They should be supported with written information when a diagnosis of suspected CHS is made. This information should also identify sources of support and advice for helping those cannabis users wishing to achieve abstinence.

Ensure that you read the full Cannabinoid Hyperemesis Syndrome Guideline

Key Information

Features that should prompt suspicion of a diagnosis of CHS:

• Severe nausea and vomiting that recurs in a cyclic pattern over months

• Age <50 at time of evaluation

• At least weekly cannabis use

• Resolution of symptoms after cannabis cessation

• Compulsive hot showers or baths with symptom relief

• Abdominal pain

• History of regular cannabis use for >1 year

For refractory nausea or vomiting in CHS, consider the use of haloperidol or capsaicin.

Prior to administering haloperidol, obtain an ECG to check for QTc prolongation and correct electrolyte abnormalities if conduction defects are present. Do not give haloperidol if the QTc is prolonged, or if a patient has Parkinson’s disease or Lewy body dementia (LBD). Patients should be monitored for acute dystonia after administration.

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