What is the name of the syndrome in a young adult with a history of cannabis use who experiences recurrent episodes of severe nausea and vomiting after smoking cannabis?

Cannabinoid Hyperemesis Syndrome (CHS)

The syndrome is called Cannabinoid Hyperemesis Syndrome (CHS), a condition characterized by recurrent episodes of severe nausea and vomiting in chronic cannabis users that paradoxically occurs despite cannabis's well-known antiemetic properties. 1

Defining Clinical Features

CHS presents with a distinctive constellation of symptoms that differentiate it from other causes of cyclic vomiting:

• Stereotypical episodic vomiting occurring at least 3 times annually, with acute onset and duration less than 1 week 1
• Pathognomonic hot water bathing behavior - compulsive use of hot showers or baths for symptom relief, observed in 44-71% of CHS patients 1, 2
• Severe abdominal pain accompanying the nausea and vomiting episodes 2, 3
• Cannabis use pattern requiring >1 year of use before symptom onset and frequency >4 times per week on average 1, 2

Critical Diagnostic Criteria

The American Gastroenterological Association requires all three of the following for definitive diagnosis 1:

• Stereotypical episodic vomiting occurring 3+ times annually
• Cannabis use >1 year before symptom onset with frequency >4 times per week
• Complete and persistent resolution of all symptoms after cannabis cessation for at least 6 months (or duration equal to 3 typical vomiting cycles for that patient)

The 6-month abstinence requirement is the only reliable diagnostic criterion that separates CHS from Cyclical Vomiting Syndrome (CVS), as both conditions present identically with episodic vomiting. 1

Pathophysiological Mechanism

The paradoxical nature of CHS stems from cannabinoids producing a biphasic effect on nausea and vomiting 3:

• Low doses have antiemetic effects
• High doses produce emesis through dysregulation of the endocannabinoid system 3
• Chronic cannabis use leads to loss of negative feedback on the hypothalamic-pituitary-adrenal axis, resulting in increased vagal nerve discharges that contribute to vomiting 1
• CB1 receptors are densely distributed in the dorsal vagal complex, a critical area for controlling emesis 1

Route of Administration

CHS can occur with any form of cannabis consumption, including edibles, as the syndrome is triggered by chronic exposure to THC regardless of the route of administration. 1 The total THC dose and duration of use are the critical factors, not the method of consumption 1. Modern cannabis products, including edibles, contain dramatically higher THC concentrations than historical products, increasing the risk of CHS 1.

Common Diagnostic Pitfalls

• CHS is frequently underdiagnosed or misdiagnosed due to limited clinician awareness, leading to extensive unnecessary testing 1, 2
• Hot water bathing behavior is present in 71% of CHS patients but also reported in 44% of CVS patients, and does not reliably distinguish between the two syndromes 1
• Always rule out life-threatening conditions first (acute abdomen, bowel obstruction, mesenteric ischemia, pancreatitis, myocardial infarction) before attributing symptoms solely to CHS 1, 2

Acute Management

Conventional antiemetics like ondansetron are often ineffective for CHS, requiring a different therapeutic approach. 2, 4

The American Gastroenterological Association recommends the following hierarchy 1, 2:

• First-line: Benzodiazepines (particularly lorazepam) are the most effective acute treatment based on multiple case series and prospective studies, providing sedating and anxiolytic effects that address the stress-mediated component 1, 4
• Second-line: Haloperidol or droperidol - butyrophenones show superior efficacy in reducing hospital length of stay by nearly 50% (6.7 vs 13.9 hours, p=0.014) 1, 5
• Adjunctive: Topical capsaicin 0.1% applied to the abdomen, which activates TRPV1 receptors and has shown consistent benefit 1, 2
• Avoid opioids entirely as they worsen nausea, carry high addiction risk, and do not address the underlying pathophysiology 1, 2

Definitive Treatment

Cannabis cessation is the only definitive treatment for CHS and must be strongly recommended. 1, 2 Complete resolution requires at least 6 months of continuous cannabis abstinence, or abstinence duration equal to at least 3 typical vomiting cycles for that patient 1, 2.

For long-term prevention, tricyclic antidepressants (particularly amitriptyline) are the mainstay of therapy 1, 2:

• Start at 25 mg at bedtime
• Titrate weekly by 25 mg increments
• Reach minimal effective dose of 75-100 mg 1, 2

Distinguishing from Cannabis Withdrawal Syndrome

Cannabis Withdrawal Syndrome presents oppositely from CHS - vomiting occurs after stopping cannabis use in withdrawal, whereas vomiting occurs during active use in CHS 6. Cannabis withdrawal symptoms typically begin within 24-72 hours of cessation, peak between days 2-6, and resolve within 14 days 6, whereas CHS requires 6+ months of abstinence for definitive resolution 1.