A 27-year-old man sits hunched over an emesis basin, skin clammy and eyes red, while the smell of cannabis clings to his sweatshirt. He reports six hours of relentless vomiting and says, almost apologetically, that the only thing that helps is standing under a very hot shower. His abdomen is uncomfortable but soft, and he has visited two emergency departments for similar episodes this year. The monitor is showing sinus tachycardia as the next decision waits.

— What’s your move? Read on.

Before you read
  • Which ED therapies work fastest, and which commonly used antiemetics often fail?
  • What must be done to prevent recurrence?

When to Think of It

Recurrent stereotyped vomiting in a frequent cannabis user, often with compulsive hot bathing and temporary relief from heat. Patients may have epigastric discomfort, dehydration, hypokalemia, acute kidney injury, or leukocytosis. Ask specifically about cannabis frequency, last use, prior similar visits, hot showers, pregnancy possibility, diabetes, medications, and co-ingestants.

Sick or Not Sick

Sick vs. not sick: the key call is whether this is uncomplicated hyperemesis or vomiting caused by a time-sensitive alternate diagnosis. Shock, peritonitis, GI bleeding, severe metabolic abnormality, altered mental status, focal neurologic findings, fever, pregnancy, or atypical pain mandates broader evaluation.

The First Fifteen Minutes

  • Obtain IV access, glucose, ECG, electrolytes, renal function, lipase, urinalysis, and pregnancy testing when applicable; give 0.9% saline or lactated Ringer’s 1 L IV, then reassess, because vomiting-related volume depletion drives tachycardia and kidney injury.
  • If ongoing vomiting is clinically significant, give ondansetron 4 mg IV or ODT, because 5-HT3 blockade may reduce emesis; reassess QTc and electrolytes before repeated doses.
  • If typical CHS persists despite initial therapy and QTc is acceptable, give haloperidol 2.5–5 mg IV/IM (or 0.05–0.1 mg/kg, maximum 5 mg), because dopamine blockade can interrupt the emetic pathway; obtain an ECG first when feasible and avoid it with marked QT prolongation, severe hypokalemia, or Parkinson disease.
  • If symptoms continue and skin is intact, apply capsaicin 0.075% cream—a thin layer to the abdomen or upper extremities, with gloves and strict eye/mucosal avoidance—because TRPV1 activation can mimic the benefit of heat. Concentrations vary by product; follow institutional protocol and wash hands after application.
  • For severe anxiety or persistent retching after exclusion of dangerous causes, give lorazepam 1–2 mg IV/PO, because anxiolysis may reduce the conditioned vomiting cycle; monitor for respiratory depression, especially with other sedatives.
  • Avoid routine opioids, which worsen nausea, constipation, and recurrent care-seeking; correct severe hypokalemia or hypomagnesemia before QT-prolonging medications.

Definitive Care & Disposition

Continue oral rehydration and electrolyte correction once vomiting stops. CT, ultrasound, or specialty consultation is driven by the differential—not by the cannabis history. Admit for persistent inability to tolerate oral intake, severe AKI, significant electrolyte abnormality, dysrhythmia, GI bleeding, pregnancy-related concerns, or an alternate diagnosis. Discharge is reasonable when vitals, renal function, electrolytes, and symptoms improve and oral intake is tolerated; provide explicit cannabis cessation counseling and primary-care/addiction follow-up.

How This One Kills

The lethal error is anchoring on CHS and missing appendicitis, bowel obstruction, diabetic ketoacidosis, pregnancy-related disease, toxic alcohol exposure, or intracranial pathology. Repeated visits do not prove CHS; they should increase confidence only after the current episode has been risk-assessed.
The Differential — What Else Looks Like This
  • Diabetic ketoacidosis — hyperglycemia, anion-gap acidosis, and ketones; confusing it with CHS delays insulin and fluids.
  • Bowel obstruction — distention, obstipation, and air-fluid levels; missing it delays decompression or surgery.
  • Acute pancreatitis — persistent epigastric pain with lipase elevation; mislabeling it as CHS delays supportive care and etiologic evaluation.
  • Pregnancy-related vomiting — positive pregnancy test and dehydration/ketosis; confusion can miss ectopic pregnancy or severe hyperemesis complications.

The Second-Day Story

Older patients may not volunteer cannabis use, and frequent users may present mainly with AKI, hypokalemia, syncope, or nonspecific abdominal discomfort rather than dramatic vomiting. Some patients do not report hot-shower behavior, while partially treated patients may have a normal examination. The diagnosis remains clinical: recurrent episodes, substantial cannabis exposure, exclusion of dangerous causes, and improvement with supportive care—while recognizing that durable resolution requires abstinence.
Back to Our Patient
Back to the 27-year-old man: his recurrent stereotyped vomiting, frequent cannabis use, hot-shower relief, soft abdomen, normal glucose and lipase, and ECG without dangerous QT prolongation make cannabinoid hyperemesis syndrome most likely after exclusion of surgical and metabolic emergencies. He receives IV crystalloid, an antiemetic, and topical capsaicin, with potassium correction guided by laboratory results; opioids are avoided. Once his tachycardia resolves and he tolerates oral fluids, he is discharged with a clear explanation that cannabis cessation—not repeated symptomatic treatment—is the intervention most likely to prevent recurrence, plus follow-up and return precautions.
Patient Presentation to Attending
How you’d present this patient on the floor — tight, pertinent positives and negatives, no rambling
“This is a 27-year-old man with recurrent vomiting, presenting with six hours of intractable nonbloody emesis and epigastric discomfort. He uses cannabis daily and reports similar episodes relieved by very hot showers, with two prior ED visits this year. He is tachycardic but normotensive, afebrile, and has a soft abdomen without focal tenderness, guarding, or distention; he has no headache, chest pain, diarrhea, or GI bleeding. Glucose and lipase are normal, pregnancy testing is not applicable, and ECG shows no significant QT prolongation. My assessment is cannabinoid hyperemesis syndrome with dehydration, after excluding an acute abdomen and metabolic emergency. I’ll give IV crystalloid, ondansetron followed by haloperidol if needed, apply topical capsaicin, replete electrolytes, and discharge only if he tolerates oral intake with cannabis-cessation counseling.”

Study Directive

  • Write a one-minute CHS differential separating it from DKA, obstruction, pancreatitis, pregnancy, and intracranial disease.
  • Memorize haloperidol, capsaicin, and fluid strategies, including QT precautions.
  • Review one ECG showing hypokalemia/QT prolongation and identify when haloperidol is unsafe.
  • Practice a 30-second cannabis-cessation counseling script and a discharge plan.

Recent Literature