Cannabinoid Hyperemesis Syndrome

What is Cannabinoid Hyperemesis Syndrome (CHS)?

Cannabinoid Hyperemesis Syndrome (CHS) is a functional gastrointestinal disorder characterised by recurrent episodes of severe nausea, vomiting, and abdominal pain in the context of chronic, heavy cannabis use.¹

A distinctive feature is temporary symptom relief with hot bathing or showering. Symptoms resolve with sustained cessation of cannabis.

• Increasingly recognised with rising cannabis availability and greater availability of more potent products over the last 20 years.²

• In the UK, cannabis is the most commonly used illicit drug, with 7.4% of adults between 16- to 59-years-old reporting having used the drug within the past year.³

• As of December 2024, all but four states in the United States have full or partial legal cannabis laws or decriminalisation laws in effect. 2.6 million Americans become new users each year; the majority of this group is under the age of 19.⁴

• CHS typically affects individuals younger than 50 years, with a median age of 28 years. Notably, the median age for cannabis initiation in these patients is 16, suggesting that early cannabis use may play a role in CHS development.⁴

• Prevalence is uncertain but likely underdiagnosed due to overlap with other vomiting syndromes and underreporting of cannabis use.

CHS typically develops after years of frequent (often daily) cannabis use, including smoked, vaped, or edible forms.

The exact mechanism of CHS is not fully understood, but several theories exist:

• Endocannabinoid system dysregulation: Chronic overstimulation of cannabinoid (CB1) receptors may paradoxically impair central antiemetic effects and delay gastric emptying.

• Hypothalamic effects: Cannabinoids may disrupt thermoregulation, explaining the compulsive hot bathing behaviour.

• Peripheral gastrointestinal effects: CB1 receptor activation in the gut may reduce motility and promote nausea and vomiting.

• Genetic susceptibility: Not all chronic cannabis users develop CHS, suggesting individual vulnerability.⁶

CHS classically progresses through three phases:¹⁷

Prodromal phase

• Early morning nausea.

• Gêne abdominale.

• Fear of vomiting.

• Continued cannabis use.

Hyperemetic phase

• Persistent, severe nausea and vomiting.

• Abdominal pain (often epigastric or periumbilical).

• Dehydration and weight loss.

• Compulsive hot showers or baths for symptom relief.

  • Symptoms often return within 10-30 minutes after hot-water bathing, which might explain why patients take up to 20 hot showers a day or sit in a hot bath as long as possible.² In extreme cases, patients will even resort to checking into a hotel to ensure a continuous supply of hot water.

• Poor response to standard antiemetics.

Recovery phase

• Resolution of symptoms after cannabis cessation.

• Return of normal eating patterns.

• Symptoms recur if cannabis use resumes.

CHS is a clinical diagnosis based on history and exclusion of other causes.

Common diagnostic features include:

• Long-term, frequent cannabis use.

• Recurrent episodes of intractable vomiting.

• Relief with hot bathing.

• Resolution of symptoms after cannabis cessation.

The Rome IV criteria support the diagnosis when symptoms are present for ≥3 months with onset ≥6 months prior.¹²

Laboratory and imaging studies are typically nonspecific and are used to rule out alternative diagnoses. Common findings may include:

• Electrolyte abnormalities (eg, hypokalaemia).

• Elevated creatinine from dehydration.

• Normal imaging studies.

Conditions to consider include:

• Cyclic vomiting syndrome (CVS).

• Acute gastroenteritis.

• Ulcère gastroduodénal.

• Gastritis or gastroesophageal reflux disease.

• Pancréatite.

• Biliary colic or cholecystitis.

• Obstruction intestinale.

• Pregnancy-related hyperemesis.

• Intracranial pathology (in selected cases).

Distinguishing CHS from CVS relies heavily on cannabis use history and symptom resolution with cessation.

Acute phase⁹

• Supportive care: Intravenous fluids and electrolyte correction.

• Antiemetics: Traditional agents (eg, ondansetron, metoclopramide) are often ineffective.⁸

• Haloperidol or droperidol: Evidence supports efficacy in reducing vomiting.⁵

• Topical capsaicin: Applied to the abdomen or arms; thought to act via TRPV1 receptors.

• Although there is substantial supporting literature for haloperidol use in adults, data on the paediatric population are limited. Benzodiazepines, in particular lorazepam and clonazepam, are the most commonly used drugs, both for their anti-emetic effects and support for cannabis withdrawal symptoms.⁷

• Hot showers or baths: Provide temporary symptomatic relief (not definitive treatment).

Definitive treatment¹⁰

• Complete cessation of cannabis use is the only proven long-term cure.

• Patient education and counselling are critical.

• Referral for substance use treatment may be appropriate.

It is important to emphasise that patients may struggle to accept that cannabis is the cause of their symptoms, making cessation challenging.⁷ CHS often presents comorbidly with attention deficit hyperactivity disorder, anxiety, and depression, and cannabis use is sometimes employed for the self-management of anxiety.

Les complications potentielles sont les suivantes :

• Déshydratation sévère.

• Electrolyte disturbances, hypophosphataemia.¹¹

• Lésions rénales aiguës.

• Oeophagitis, Mallory–Weiss tears, pneumomediastinum, oesophageal perforation (Boerhaave syndrome), pneumothorax, and pneumopericardium.¹²¹³

• Weight loss and malnutrition.

• Burns (from hot water).¹⁴

• Frequent emergency department visits and hospital admissions.

The prognosis is excellent with sustained cannabis cessation, with most patients experiencing complete symptom resolution within days to weeks. Relapse is common if cannabis use is resumed.

Long-term outcomes depend largely on the patient’s ability to abstain from cannabis and engage in follow-up care.