Cannabinoid Hyperemesis Syndrome


  • Occurs in the context of at least weekly cannabis consumption, for at least 1 year - NOT an intoxication effect from a single large ingestion
  • Episode timing and severity does not correlate with amount of cannabis consumed, and patient may find cannabis temporarily relieves symptoms during an episode

Phase 1: Prodromal

  • Can last months to years
  • Characterised by nausea, abdominal discomfort, emetophobia
  • Symptomatic on one or more days of the week

Phase 2: Hyper-emetic

  • Intractable vomiting, abdominal pain, weight loss
  • Symptoms present on waking up
  • Episodes lasting several days, with weeks-months of remission between
  • Patients report improvement in symptoms in hot showers or baths (compulsive use of same)

Phase 3: Recovery

  • Occurs when cannabis consumption is stopped
  • Symptoms may improve within 24-48 hrs, with return of symptoms if cannabis consumed again


Diagnosis is based on clinical history:

  1. Cyclical pattern of vomiting:
    • Episodes last <7 consecutive days
    • Can have asymptomatic periods of weeks to months between episodes
  2. Prolonged cannabis use:
    • >Once per week for >1 year
  3. Exclusion of alternative diagnoses:
    • CHS should not present with abnormal vital signs, abnormal bowel movements, focal abdominal pain, peritonitis or jaundice


Evaluate for complications / DDx.

  • U&E - Electrolytes, AKI
  • Metabolic acidosis/alkalosis
  • Glucose and Ketones
  • Pregnancy test
  • ECG - QTc, (before admin. of antiemetics)

Differential Dx

Red flags

  • ↓Wt (esp. age >50 yrs)
  • Abdominal mass
  • Change in bowel habit
  • Anaemia
  • LFT abnormalities


  • The only definitive treatment for CHS is cessation of cannabis consumption.
  • Management can be challenging, as CHS is often resistant to traditional antiemetics (ondansetron, antihistamines), however normal treatment of nausea and vomiting can be trialled in the first instance.
  • Avoid metoclopramide (↑ risk of EPS if haloperidol co-prescribed).

Haloperidol IM 0.05mg/kg (max 5mg)

  • Olanzapine if allergy to haloperidol, ↑QTc or Hx of extrapyramidal sympt. with haloperidol/PD/LBD

Capsaicin 0.1% cream TOP - applied to abdomen


  • Hot Bath/Shower
  • Benzodiazepines - Lorazepam 1-2mg IV
  • Limited evidence for TCAs, levetiracetam, PPIs and Β-blockers

Follow up

  • Cannabis abstinence is the only long term treatment for CHS
  • GP follow up, sign posting advice, or referral to local supports may improve successful cessation
  • Reasonable to suggest non-emergent OGD as outpatient if newly Dx/not previously Ix


Content by Dr Amy Brennan, Regina Lee [Pharmacy CUH], Dr Iomhar O'Sullivan. Last review Dr ÍOS 24/03/24.