Cannabis Hyperemesis Syndrome: How the Same System That Prevents Nausea Can Also Cause It | Research

The takeaway

A narrative review explained how CHS arises from a biphasic response in the endocannabinoid system, where chronic cannabis use flips the antiemetic effect into a proemetic one, and distinguished CHS from cyclic vomiting syndrome.

Emergency physicians; gastroenterologists; patients experiencing unexplained cyclic vomiting who use cannabis regularly.

Cannabis produces biphasic effects: antiemetic acutely, proemetic with chronic heavy use

What the researchers found

The endocannabinoid system produces biphasic effects: acute cannabis use is antiemetic, but chronic heavy use can trigger a proemetic response leading to CHS. The review outlined key differences between CHS and cyclic vomiting syndrome and described the pathophysiology involving desensitization of CB1 receptors in the gut.

Why it matters

CHS is frequently misdiagnosed because it shares symptoms with many gastrointestinal conditions. Understanding the biphasic mechanism explains the counterintuitive finding that an antiemetic substance can cause severe vomiting, helping clinicians recognize and properly diagnose CHS.

The numbers in context

Cannabis has over 400 chemicals and more than 100 identified cannabinoids. CHS incidence is expected to rise with increasing cannabis access. The review described three CHS phases: prodromal, hyperemetic, and recovery.

How the study worked

Narrative review synthesizing evidence on the endocannabinoid system's role in CHS pathophysiology, clinical features, diagnosis, treatment, and differentiation from similar conditions, particularly cyclic vomiting syndrome.

What this study cannot tell us

Narrative review format without systematic search methodology. CHS pathophysiology is still not completely understood. The review relied on case reports and small studies given the limited controlled research on CHS.

How to read the evidence

Moderate: comprehensive narrative review published in a gastroenterology journal, synthesizing available evidence on CHS pathophysiology.

When this study was published

Published in 2022.

The bigger picture

As CHS becomes more common, the medical community needs clear frameworks for diagnosis and treatment. The distinction from cyclic vomiting syndrome is particularly important because treatments differ, and misdiagnosis delays appropriate care.

Questions still open

What determines which heavy cannabis users develop CHS and which do not? Are there genetic factors that predict CHS susceptibility? Would standardized diagnostic criteria reduce CHS misdiagnosis rates?

Common questions

How can cannabis cause vomiting if it is used to treat nausea?

The endocannabinoid system produces biphasic effects. Acute cannabis exposure activates CB1 receptors that suppress nausea. But chronic heavy use can desensitize these receptors, eventually reversing the effect and triggering severe, cyclic vomiting.

How is CHS different from cyclic vomiting syndrome?

CHS requires a history of regular cannabis use and resolves with sustained abstinence. CVS occurs independent of cannabis use and has different underlying causes. The compulsive hot bathing that many CHS patients use for relief is a distinguishing feature.

Read the original research

Endocannabinoid system and cannabis hyperemesis syndrome: a narrative update.

European journal of gastroenterology & hepatology, 34(1), 1-8

View on PubMed ↗Publisher’s paper ↗

Citation

Perisetti, Abhilash; Goyal, Hemant. (2022). Endocannabinoid system and cannabis hyperemesis syndrome: a narrative update.. European journal of gastroenterology & hepatology, 34(1), 1-8. https://doi.org/10.1097/MEG.0000000000001992