Cannabinoid Hyperemesis Syndrome (CHS)
Overview
Cannabinoid Hyperemesis Syndrome (CHS) is a clinical syndrome of recurrent, severe nausea and vomiting seen in people with prolonged, regular cannabis use. Presentations are often cyclical and stereotyped. A characteristic feature is repeated hot showers or baths that transiently relieve symptoms.
There are no diagnostic laboratory or imaging tests - diagnosis in the ED is usually “suspected CHS”; definitive confirmation (Rome IV) requires sustained symptom resolution after cannabis cessation (RCEM 2024).
When to suspect CHS
- Recurrent or cyclical vomiting in a person with regular long‑term cannabis use (typically at least weekly).
- Age usually below 50, although adolescents and older patients can be affected.
- Compulsive hot bathing or showering that relieves symptoms.
- Poor or absent response to standard antiemetics.
- No alternative red‑flag features suggesting another diagnosis.
Pathophysiology
- The precise mechanism is not established.
- Hypotheses include paradoxical effects of cannabinoids on the endocannabinoid system, altered gastrointestinal motility and emetic pathways, and cutaneous thermoregulatory modulation (which may explain hot‑water relief).
- Synthetic cannabinoid receptor agonists (SCRAs) can cause more severe or atypical presentations and should be specifically asked about (ACMD).