Cannabinoid Hyperemesis Syndrome (CHS) continues to be a major clinical challenge in the emergency department. Patients present with severe abdominal pain, intractable vomiting, and significant fluid and electrolyte derangements. CHS often affects people who have been using cannabis routinely for months to years – it can be difficult for patients to understand that their symptoms are related to cannabis. 

Today, emergency pharmacist Haley Burhans joins us to discuss first-line treatments, fluid management, discharge strategies, and how to navigate these tough bedside conversations.

First-Line Therapies: Haldol vs. Droperidol

  • Haloperidol (Haldol): Supported by the HAVOC trial (haloperidol vs. placebo), which showed a reduction in symptoms and ED length of stay.
  • Droperidol: Highly effective alternative with similar dopaminergic mechanism of action. May carry a lower risk of extrapyramidal symptoms compared to haloperidol. 
  • Capsaicin Cream: addresses the TRPV1 pathway thought to drive CHS. Patients often dislike it as it causes a burning sensation on the skin and can be inadvertently spread to eyes or face. Can be an option if symptoms persist after trying the above meds and hot showers aren’t feasible. 

Backup Options & Anti-Emetics

  • Alternative Dopaminergic Agents: Metoclopramide or prochlorperazine can be used.
  • Standard Anti-Emetics (e.g., Ondansetron):
    • Serotonergic anti-emetics generally fail to address the underlying CHS pathway.
    • However, a single dose of ondansetron given alongside a butyrophenone (haloperidol/droperidol) is reasonable if you suspect co-existing etiologies.

QTc Prolongation Warning:

Chronic vomiting leads to electrolyte depletion. Combining anti-emetics and haloperidol or droperidol increases the risk of QTc prolongation.

Baseline EKG: Not strictly required for every low-risk patient, but strongly recommended for patients with multiple risk factors (e.g., co-ingestion/use of methadone, history of heart failure, or severe baseline bradycardia).

Fluid Resuscitation & Electrolyte Management

CHS patients can vomit to the point of severe dehydration and profound electrolyte/acid-base derangements.

  • Fluid Selection:
    • Normal Saline (NS): A solid choice for initial volume resuscitation when sodium and chloride are severely depleted.
    • Lactated Ringer’s (LR): Ideal as a follow-up or maintenance fluid because it contains a small amount potassium.
  • Potassium Repletion: Oral repletion may not be tolerated in the acute setting. Consider IV potassium repletion in the ED, followed by oral home supplementation once nausea is controlled.
  • Magnesium: While acute vomiting primarily drives potassium loss, consider IV magnesium if Mg is low or there is concern for QTc prolongation.

Discharge Planning: What to Send Home

  • Low-Dose Olanzapine ODT:
    • Send the patient home with 2.5 mg Olanzapine ODT (orally disintegrating tablets).
    • Why it works: It dissolves instantly on the tongue, bypassing the stomach, and provides extended dopaminergic coverage over the multi-day washout period. 
  • Pharmacokinetics Pearl:
    • Infrequent user THC half-life: ~1.3 hours (cleared in 5–6 hours).
    • Chronic user THC half-life: THC accumulates in adipose tissue. In heavy users, therapeutic levels can persist for up to 2 weeks, driving prolonged receptor dysregulation even after cessation.

Navigating the Bedside Conversation

Explaining to a chronic user that their daily cannabis—the very thing they use to relieve nausea—is causing their illness requires empathy and validation.

  1. Explain the Neurological Link: Cannabis acts on receptors throughout the entire body, including the brain’s nausea center and the nervous system of the gut. Chronic, heavy saturation can paradoxically overload these pathways.
  2. Validate Their Experience: Acknowledge how counterintuitive it feels: “I know it’s hard to believe that something you’ve used for years to feel better is causing this, but long-term daily use can change how your body processes it.”
  3. Set Realistic Expectations: Reiterate that symptoms will not resolve overnight. Even after stopping, it takes time for the pathways to recalibrate.

What do you find most helpful for treating CHS? How do you have these difficult conversaions with your patients? Share your experience with us on social media @empulsepodcast or at ucdavisem.com

Hosts:

Dr. Julia Magaña, Professor of Pediatric Emergency Medicine at UC Davis

Dr. Sarah Medeiros, Professor of Emergency Medicine at UC Davis

Guests:

Haley Burhans, PharmD, Emergency Medicine Clinical Pharmacist at UC Davis

Resources:

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. Acad Emerg Med. 2024 May;31(5):425-455. doi: 10.1111/acem.14911. PMID: 38747203.

Rech MA, Shalaby M, Gage KA, Gottlieb M. Managing Cannabinoid Hyperemesis Syndrome. Ann Emerg Med. 2026 Jun;87(6):717-722. doi: 10.1016/j.annemergmed.2025.12.024. Epub 2026 Feb 3. PMID: 41632059.

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Thank you to the UC Davis Department of Emergency Medicine for supporting this podcast and to Orlando Magaña at OM Productions for audio production services.

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