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Study breakdown

THC-induced nausea involves stress response dysregulation and is not blocked by standard anti-nausea drugs

Animal StudyPreliminary evidence
The takeaway

THC-induced nausea in rats was blocked by stress-response inhibitors and benzodiazepines but not by ondansetron (a standard anti-emetic), supporting the theory that cannabinoid hyperemesis syndrome is a stress-mediated condition.

CHS researchers, emergency physicians, pharmacologists studying nausea mechanisms

Standard anti-emetic ondansetron failed; 6 stress-response inhibitors and a benzodiazepine worked

What the researchers found

Antalarmin (CRH antagonist), MJN110 (2-AG elevator), URB597 (AEA elevator), propranolol, WAY-100635, and chlordiazepoxide all blocked THC-induced conditioned gaping. The standard anti-emetic ondansetron did not. THC at 10 mg/kg significantly elevated corticosterone compared to 0.5 mg/kg, showing dose-dependent HPA activation.

Why it matters

This explains why CHS patients do not respond to standard anti-nausea medications but find relief from hot showers and benzodiazepines: the nausea is driven by stress pathway activation, not the typical serotonin-mediated mechanism.

The numbers in context

6 different stress-response inhibitors blocked THC nausea. Ondansetron at 0.1 and 0.01 mg/kg did not. THC 10 mg/kg produced significantly higher corticosterone than 0 or 0.5 mg/kg.

How the study worked

Male rats in a conditioned gaping model of nausea. THC (10 mg/kg) paired with saccharin. Pre-treatments tested: CRH antagonist, endocannabinoid enhancers (MJN110, URB597), propranolol, WAY-100635, ondansetron, chlordiazepoxide. Corticosterone measured at different THC doses.

What this study cannot tell us

Animal model; male rats only; conditioned gaping is a proxy for nausea; high-dose acute THC may not fully recapitulate chronic CHS in humans.

How to read the evidence

Comprehensive mechanistic animal study testing multiple pharmacological targets.

When this study was published

Published in 2020.

The bigger picture

This mechanistic work suggests CHS treatment should target the stress response (CRH antagonists, benzodiazepines, or endocannabinoid modulators) rather than traditional anti-emetic pathways.

Questions still open

  • Would CRH antagonists be effective treatments for CHS in humans? Could endocannabinoid enhancers prevent CHS in chronic users?

Common questions

Why don't regular anti-nausea drugs help with CHS?
This study found that THC-induced nausea operates through the stress response (HPA axis) rather than the serotonin pathway targeted by standard anti-emetics like ondansetron. This explains clinical reports that ondansetron is ineffective for CHS.
What does work for CHS-related nausea?
In rats, drugs that block the stress response (CRH antagonists, beta-blockers, endocannabinoid enhancers) and benzodiazepines all reduced THC-induced nausea. This aligns with clinical observations that benzodiazepines and hot showers (which reduce stress) help CHS patients.

Read the original research

Role of the stress response and the endocannabinoid system in Δ9-tetrahydrocannabinol (THC)-induced nausea.

Psychopharmacology, 237(7), 2187-2199

Citation

DeVuono, Marieka V; La Caprara, Olivia; Sullivan, Megan T; Bath, Alexandra; Petrie, Gavin N; Limebeer, Cheryl L; Rock, Erin M; Hill, Matthew N; Parker, Linda A. (2020). Role of the stress response and the endocannabinoid system in Δ9-tetrahydrocannabinol (THC)-induced nausea.. Psychopharmacology, 237(7), 2187-2199. https://doi.org/10.1007/s00213-020-05529-5

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