01Approach to the Critical Patient/attcp43

Immediate priorities

›Airway and hemodynamic threats

›Airway risk from intractable vomiting

›Active emesis with decreased level of consciousness

›Inability to protect airway

›If unable to protect airway, proceed to definitive airway management

›Hemodynamic instability from severe dehydration

›SBP < 90 mmHg

›Heart rate > 120 bpm with poor skin turgor

›Signs of end-organ hypoperfusion

›Acute kidney injury from volume depletion

›Elevated creatinine on presentation

›Oliguria or anuria

›Escalate if AKI not responding to initial IV fluids

Monitoring and targets

›Monitoring bundle for CHS

›Continuous cardiac monitoring if haloperidol or droperidol administered

›QTc baseline before antipsychotic administration

›Repeat ECG at 30-60 minutes if QTc borderline

›QTc > 500 ms: withhold further dopamine antagonist, reassess

›IV access and fluid status

›Two large-bore IVs for significant dehydration

›Urine output target > 0.5 ml/kg/hr

›Electrolyte monitoring

›Potassium — CHS patients have significantly lower K than CVS controls

›Magnesium — hypomagnesemia potentiates hypokalemia

›Repeat BMP 2-4 hours after repletion

02History/hx52

Core presentation

›Stereotypical episodic vomiting pattern

›Profuse nausea and vomiting recurring at least 3 times per year

›Episodes lasting 24-48 hours, up to 7-10 days

›Early-morning predominance of symptoms

›Diffuse abdominal pain, cramping in character

Cannabis use history

›Use characterization

›Frequency — typically 4 or more times per week (68% of cases daily)

›Duration — typically greater than 1 year; mean 6.6 years before symptom onset

›Route — smoking, vaping, concentrates, waxes; edible-associated cases are rare

›Potency — high-potency products (vapes, concentrates) associated with higher risk

›Collateral from family or friends essential — patients frequently underreport use

Pathognomonic feature

›Hot water bathing behavior

›Compulsive hot showers or baths for symptom relief

›Reported in approximately 71% of patients

›Some patients spend hours in the shower during hyperemetic phase

›Temporary relief only — not a treatment; risk of burns and worsening dehydration

Three-phase clinical pattern

›Prodromal phase

›Early morning nausea

›Food avoidance and anorexia

›Normal or near-normal vomiting frequency

›Hyperemetic phase

›Severe intractable vomiting and nausea

›Diffuse abdominal pain

›Hot water bathing for relief

03Physical Exam/exam31

Vital signs

›Hemodynamic assessment

›Tachycardia — most common finding; reflects volume depletion

›Hypotension or orthostatic hypotension

›CHS patients have higher systolic BP compared to CVS controls

›Fever — if present, consider alternative or concurrent diagnosis

General appearance

›Clinical impression

›Distressed, diaphoretic, actively retching

›Signs of dehydration

›Dry mucous membranes

›Poor skin turgor

›Sunken eyes

›Decreased axillary moisture

Abdominal exam

›Abdominal findings

›Diffuse tenderness without peritoneal signs

›Soft, non-distended abdomen

›Normal or hyperactive bowel sounds

›Absence of rebound tenderness or guarding is expected

›Peritoneal signs absent — if present, pursue alternative diagnosis urgently

›Involuntary guarding

›Rebound tenderness

›Rigidity

Skin exam

›Integumentary findings

›Erythema or superficial burns from prolonged hot water exposure

›Typically on trunk and upper extremities

04Differential Diagnosis/ddx43

Gastrointestinal mimics

›Cyclic vomiting syndrome

›ICD-10: G43.A0, G43.A1

›Nearly identical presentation — distinguished by temporal association with cannabis and resolution with cessation

›Migraine association in CVS (absent in CHS)

›Gastroparesis

›ICD-10: K31.84

›Many CHS patients previously misdiagnosed as gastroparesis

›Gastric emptying study may be abnormal in both

›Bowel obstruction

›ICD-10: K56.60

›Surgical emergency — assess for abdominal distension, absent bowel sounds, obstipation

›CT abdomen/pelvis required if suspected

›Pancreatitis

›ICD-10: K85.90

›Elevated lipase distinguishes — check in all CHS presentations

›Epigastric pain radiating to back

Surgical emergencies

›Mesenteric ischemia

›ICD-10: K55.1

›Peritoneal signs, pain out of proportion to exam, hemodynamic instability

›Elevated lactate, leukocytosis

›Appendicitis

›ICD-10: K37

›Right iliac fossa tenderness, migration of pain, low-grade fever

›Peptic ulcer disease with perforation

›ICD-10: K27.1

›Free air on upright CXR or CT

05Laboratory Tests/lt43

Core metabolic panel

›Basic metabolic panel

›Hypokalemia — significantly lower in CHS than CVS controls; correct aggressively

›Target potassium > 3.5 mmol/l

›Oral or IV repletion based on severity

›Hyponatremia — from vomiting-related losses

›Elevated BUN and creatinine — prerenal AKI from dehydration

›BUN:creatinine ratio > 20:1 suggests prerenal etiology

›Metabolic alkalosis — from vomiting-induced H+ loss

›Bicarbonate typically elevated

›pH > 7.45 on VBG if significant

Point-of-care and targeted labs

›Urine drug screen

›Confirm cannabis use if patient denies

›Positive THC supports diagnosis

›Note: THC metabolites persist for days to weeks in chronic users

›Urinalysis

›Ketonuria from starvation ketosis

›Elevated specific gravity indicating dehydration

›Absence of pyuria reduces infectious etiology

›Pregnancy test

›Mandatory in all reproductive-age patients

›Urine or serum beta-hCG

›Lipase

›Elevated in pancreatitis — upper limit of normal is approximately 3x ULN for diagnosis

›Normal in CHS

Secondary labs

›Complete blood count

06Diagnostic Tests/dt41

Scoring Systems

›Rome IV criteria for cyclic vomiting syndrome

›Stereotypical episodic vomiting attacks lasting less than 1 week

›At least 3 discrete episodes in the prior year

›Absence of vomiting between episodes

›CHS classified as CVS subtype under Rome IV

›CUDIT-R — Cannabis Use Disorder Identification Test Revised

›Validated 8-item screening tool for cannabis use disorder

›Score 12 or greater indicates probable cannabis use disorder

›Useful for establishing use severity and guiding cessation counseling

›Symptom pattern scoring

›Three-phase pattern fulfillment: prodromal, hyperemetic, recovery

›Hot water bathing behavior presence

›Resolution with sustained cannabis cessation confirms diagnosis

MRI

›Brain MRI

›Not indicated in typical CHS presentation

›Indications: focal neurologic deficits, altered consciousness, concern for intracranial pathology

›Diffusion-weighted imaging for acute ischemia if focal findings

›Abdominal MRI

›Not first-line in ED setting for CHS

›Role in outpatient workup if CT findings equivocal

›MRCP if biliary pathology suspected and radiation a concern

CT

›CT abdomen and pelvis

›Not routinely indicated in known recurrent CHS with benign abdominal exam

›Imaging yield is low: only 2.4% of CT in CHS/CVS patients showed abnormalities

›Indications for CT

07Disposition/dispo36

Discharge criteria

›Criteria for safe discharge

›Symptoms controlled with antiemetic therapy

›Tolerating oral fluids without vomiting for 1-2 hours

›Able to maintain oral hydration

›Electrolytes corrected or mild and safe for outpatient management

›Potassium > 3.0 mmol/l acceptable for discharge with supplement

›Creatinine returning toward baseline

›Reliable follow-up arranged within 1-2 weeks

›Patient counseled on CHS diagnosis and cannabis cessation

Admission criteria

›Indications for hospital admission

›Intractable vomiting despite adequate ED treatment

›Failed haloperidol, droperidol, and capsaicin

›Unable to maintain oral hydration after 4-6 hours of IV therapy

›Significant AKI not responding to IV fluids

›Creatinine not trending down with resuscitation

›Severe electrolyte derangement

›Potassium < 2.5 mmol/l

›Hyponatremia < 128 mmol/l

›Hemodynamic instability

›Inability to tolerate oral intake at time of reassessment

Observation

›Observation unit criteria

›Prolonged IV hydration required beyond typical ED visit

›Repeated antiemetic dosing cycles needed

›Electrolyte repletion requiring monitoring

›Uncertain diagnosis requiring additional workup

08Treatment/t71

Immediate fluid resuscitation

›IV fluid therapy

›Initiate IV fluid resuscitation without delay

›Normal saline or lactated Ringer 500-1000 ml bolus for moderate-severe dehydration

›Reassess hemodynamic response after each bolus

›Maintenance fluid after bolus

›150-200 ml/hr until tolerating oral intake

›Titrate to urine output > 0.5 ml/kg/hr

›Electrolyte repletion concurrent with hydration

›Potassium chloride 10-20 mEq/hr IV if serum K < 3.0 mmol/l

›Magnesium sulfate 2 g IV over 20 minutes if < 0.8 mmol/l

First-line antiemetic therapy

›Haloperidol — first-line per SAEM GRACE-4 and HaVOC RCT evidence

›Haloperidol 0.05 mg/kg IV (typical dose 2.5-5 mg IV)

›Onset 10-20 minutes

›Reduced ED length of stay by approximately 2.5 hours versus ondansetron in RCT

›Monitor QTc before and 30-60 minutes after administration

›Diphenhydramine 25 mg IV co-administration to reduce akathisia risk

›Droperidol 0.625-1.25 mg IV — alternative dopamine antagonist

›Also recommended by SAEM GRACE-4 guidelines

›Similar QTc monitoring requirements

›Onset 3-10 minutes

Topical therapy

›Capsaicin cream

›Capsaicin 0.075-0.1% topical cream applied to upper abdomen

›Activates TRPV1 receptors — proposed mechanism involves the same receptor modulated by THC

›Low risk; may be applied by patient

›Warn patient of burning sensation at application site

›Can be combined with IV antiemetics

›Mixed evidence but endorsed by SAEM GRACE-4 guidelines

›Hot shower access

›Allow if clinically safe and monitoring permits

›Temporary symptomatic relief only

›Risk of burns from prolonged exposure

Second-line and adjunctive antiemetics

›Ondansetron

›Ondansetron 4-8 mg IV

›Often ineffective as monotherapy in CHS

›May provide partial relief as adjunct

›Class effect: serotonin 5-HT3 antagonist — insufficient mechanistic match for CHS

›Benzodiazepines

›Lorazepam 1-2 mg IV

›Effective in some patients per expert consensus

›SAEM GRACE-4 recommends against first-line use

›Use if haloperidol/droperidol insufficient or contraindicated

Agents to avoid

›Ineffective or harmful agents

›Metoclopramide — typically ineffective in CHS; dopamine antagonist with inferior efficacy compared to haloperidol

›Prochlorperazine — limited evidence for CHS specifically

›Opioids — proemetic, worsen gastroparesis, high addiction potential

›Reserve only if all other agents have failed

›Opioid administration increases recidivism risk

Emerging therapies

›Aprepitant — NK-1 receptor antagonist

›Aprepitant 125 mg oral or IV (fosaprepitant 150 mg IV)

›Case reports and pediatric series showing rapid symptom resolution

›Use when standard therapies fail

›Mechanism: substance P/NK-1 pathway implicated in CHS pathophysiology

Long-term management

›Cannabis cessation — definitive treatment

›Only intervention proven to eliminate CHS

›Symptoms typically resolve within days to weeks of complete cessation

›Recurrence expected with any resumption of cannabis use

›Reducing use may decrease frequency but will not eliminate the syndrome

›Cessation support

›Addiction medicine referral for cannabis use disorder

›Psychosocial interventions and motivational interviewing

›Avoid cold-turkey cessation without support — significant withdrawal and high recidivism

›Amitriptyline — prophylactic maintenance therapy

›Amitriptyline 25 mg at bedtime

›Titrate to 75-100 mg over 4-6 weeks

›Efficacious in approximately 70% of patients

›Taper after 6-12 months of remission and cannabis abstinence

›Monitor for anticholinergic side effects and QTc prolongation

›Comorbidity treatment

›Anxiety and depression treatment — critical for cessation success

›Concurrent substance use disorder management

›Sleep disorder treatment — cannabis withdrawal commonly causes insomnia

09Special Populations/sp54

Pregnancy

›Pregnancy considerations in CHS

›Pregnancy test mandatory in all reproductive-age patients before attributing diagnosis to CHS

›Hyperemesis gravidarum can coexist with CHS — cannabis does not exclude pregnancy

›Beta-hCG urine or serum

›Cannabis use in pregnancy

›Associated with fetal growth restriction, preterm birth, and neurodevelopmental effects

›Cannabis cessation is especially critical in pregnancy

›No safe level of cannabis use in pregnancy established

›Medication safety in pregnancy

›Haloperidol — Category C; use with caution; neonatal extrapyramidal effects reported

›Droperidol — Category C; limited data; use if benefit outweighs risk

›Ondansetron — preferred antiemetic in pregnancy for safety profile

›Capsaicin — limited systemic absorption; generally considered low risk

›Amitriptyline — avoid in first trimester; Category C; discuss with obstetrics

›Hydration and electrolyte correction priorities

›Aggressive IV hydration especially important in pregnant patients

›Fetal monitoring consideration if late second or third trimester

Geriatric

›Older adult considerations

›CHS less common in older adults but increasing with cannabis legalization

›Consider in any older adult with recurrent unexplained vomiting and cannabis use

›Mean age of CHS is approximately 30 years — presentations in elderly are atypical

›Dehydration risk

›Reduced physiologic reserve amplifies AKI risk

›Baseline creatinine elevation common — compare to prior values

›More aggressive hydration monitoring required

›Medication concerns

10Background/b54

Epidemiology

›Prevalence and incidence

›Increasing prevalence parallel to cannabis legalization and rising THC potency

›Estimated to affect 2.7 million Americans annually (based on cannabis-use disorder rates)

›ED presentations for CHS increased 8-fold between 2006 and 2016 in some US regions

›Male predominance — 69% of cases

›Mean age approximately 30 years at diagnosis

›Mean duration of cannabis use before symptom onset approximately 6.6 years

›Burden of disease

›Patients average multiple ED visits before diagnosis

›Significant healthcare costs from repeated imaging, labs, and admissions during diagnostic odyssey

›Associated with AKI in up to 30% of hospitalized cases in some series

›Death is rare but documented — typically from dehydration-related complications

›Cannabis landscape context

›Rising THC potency — modern concentrates reach 70-90% THC versus 1-5% in 1970s products

›Legalization associated with increased prevalence of CHS in affected states and provinces

Pathophysiology

›Proposed mechanisms

›Cannabinoid receptor dysregulation

›CB1 receptors expressed throughout the GI tract — high-dose chronic THC leads to receptor desensitization

›Paradoxical proemetic effect at high chronic doses despite acute antiemetic effects at low doses

›Autonomic dysfunction from CB1 receptor modulation in the hypothalamus

›TRPV1 receptor involvement

›Transient receptor potential vanilloid 1 (TRPV1) expressed on sensory neurons and in the gut

›High-dose chronic THC activates TRPV1, producing nausea and vomiting

›Mechanism explains therapeutic response to capsaicin (TRPV1 agonist causing receptor desensitization) and hot water (heat activates TRPV1, temporarily overriding proemetic signaling)

›Hypothalamic thermoregulation dysregulation

›Hot bathing behavior explained by hypothalamic temperature set-point changes from chronic cannabis

11Patient Discharge Instructions/pdi32

copy discharge instructions

›Your diagnosis is Cannabinoid Hyperemesis Syndrome

›This condition is directly caused by regular, heavy cannabis use

›Symptoms will continue to return as long as you use cannabis

›The only cure is complete and permanent cannabis cessation

›Medications prescribed at discharge

›Antiemetic medication as prescribed — take as directed for nausea

›Potassium supplement if prescribed — take with food

›Amitriptyline if prescribed — take at bedtime; may cause drowsiness

›Do not drive or operate machinery until you know how it affects you

›Do not take with alcohol

›Hydration instructions

›Drink small sips of clear fluids frequently — do not gulp large amounts

›Clear liquids first: water, diluted juice, ginger ale, electrolyte solutions

›Advance to bland foods (crackers, toast, rice, bananas) when tolerating liquids

›Avoid caffeine and alcohol

›Hot shower warning

›Hot showers may provide temporary relief but are not a treatment

›Prolonged hot water exposure can cause serious burns

›Do not spend more than 10-15 minutes in a hot shower

›Cannabis cessation resources

›Contact your family doctor for referral to addiction medicine

›Cannabis withdrawal is common — symptoms include irritability, insomnia, anxiety

›Withdrawal peaks at 24-72 hours and typically resolves within 2 weeks

›Do not attempt cessation without support if you have been a heavy daily user

›Return to emergency department immediately if

›Unable to keep any fluids down for more than 6 hours

›Blood in your vomit

12References/r20

Guidelines and key sources

›SAEM GRACE-4 guidelines — primary ED management reference

›Borgundvaag B, Bellolio F, Miles I, et al. Guidelines for Reasonable and Appropriate Care in the Emergency Department (GRACE-4): Alcohol Use Disorder and Cannabinoid Hyperemesis Syndrome Management in the Emergency Department. Academic Emergency Medicine. 2024. doi:10.1111/acem.14911

›Recommends haloperidol and droperidol as first-line; endorses topical capsaicin; advises against opioids

›AGA Clinical Practice Update 2024

›Rubio-Tapia A, McCallum R, Camilleri M. AGA Clinical Practice Update on Diagnosis and Management of Cannabinoid Hyperemesis Syndrome: Commentary. Gastroenterology. 2024. doi:10.1053/j.gastro.2024.01.024

›Endorses amitriptyline prophylaxis; emphasizes cannabis cessation as definitive therapy

›HaVOC Randomized Controlled Trial

›Ruberto AJ, Sivilotti MLA, Forrester S, et al. Intravenous Haloperidol Versus Ondansetron for Cannabis Hyperemesis Syndrome (HaVOC): A Randomized, Controlled Trial. Annals of Emergency Medicine. 2021. PMID 33160719

›Haloperidol superior to ondansetron — reduced ED LOS by approximately 2.5 hours

Supporting references

›Epidemiology and burden

›Swartz JA, Franceschini D. Cannabinoid Hyperemesis Syndrome, 2016 to 2022. JAMA Network Open. 2025. doi:10.1001/jamanetworkopen.2025.45310

›Gajendran M, Sifuentes J, Bashashati M, McCallum R. Cannabinoid Hyperemesis Syndrome: Definition, Pathophysiology, Clinical Spectrum, Insights Into Acute and Long-Term Management. Journal of Investigative Medicine. 2020. PMID 33115959

›Pediatric references

›Sigal A, Padilla G, Carroll T, Mautone SG. Cannabinoid Hyperemesis Syndrome in Adolescents: The Role of Aprepitant as a New Treatment Option for Rapid Symptom Relief. Journal of Adolescent Health. 2025. PMID 40965394

›Karrento K, Rosen JM, Tarbell SE, et al. NASPGHAN 2025 Guidelines for Management of Cyclic Vomiting Syndrome in Children. Journal of Pediatric Gastroenterology and Nutrition. 2025

›Seabrook JA, Seabrook M, Gilliland JA. Cannabis Hyperemesis Syndrome in Youth: Clinical Insights and Public Health Implications. International Journal of Environmental Research and Public Health. 2025. PMID 40283856

›Differential diagnosis and review

›Gorelick DA. Cannabis-Related Disorders and Toxic Effects. New England Journal of Medicine. 2023. doi:10.1056/NEJMra2212152

›Shah M, Jergel A, George RP, Jenkins E, Bashaw H. Distinguishing Clinical Features of Cannabinoid Hyperemesis Syndrome and Cyclic Vomiting Syndrome: A Retrospective Cohort Study. Journal of Pediatrics. 2024. PMID 38615942

›Lapoint J, Meyer S, Yu CK, et al. Cannabinoid Hyperemesis Syndrome: Public Health Implications and a Novel Model Treatment Guideline. Western Journal of Emergency Medicine. 2018. PMID 29560069

Evidence & Review

Evidence & Review