CBD Reduces Nausea and Vomiting by Activating Serotonin Receptors in the Brain | Research

The takeaway

CBD suppressed vomiting in shrews and nausea-like behavior in rats by indirectly activating serotonin 5-HT1A receptors in the dorsal raphe nucleus, a specific brainstem region.

Read this if you are interested in how CBD works against nausea at the brain level.

CBD and a serotonin agonist worked synergistically against nausea

What the researchers found

Researchers demonstrated that CBD's anti-nausea and anti-vomiting effects depend on serotonin 5-HT1A receptors in a specific brain region called the dorsal raphe nucleus (DRN). When 5-HT1A receptor antagonists were administered either systemically or directly into the DRN, CBD's effects were completely blocked.

CBD injected directly into the DRN suppressed nausea-like behavior, and this was reversed by a systemic 5-HT1A antagonist. In vitro studies confirmed that CBD enhanced the ability of 5-HT1A agonists to activate their receptors in brainstem tissue. Low doses of CBD and a 5-HT1A agonist worked synergistically when combined.

Why it matters

Nausea and vomiting are common side effects of chemotherapy and other treatments. Understanding exactly how CBD reduces these symptoms, through serotonin receptors in a specific brain region, could help develop more targeted anti-nausea medications and explain why CBD helps some patients with treatment-resistant nausea.

The numbers in context

CBD suppressed vomiting induced by 3 different triggers (nicotine, lithium chloride, cisplatin at 20 mg/kg). CBD showed a bell-shaped dose-response curve in vitro. Synergistic anti-nausea effects were observed when CBD was combined with the 5-HT1A agonist 8-OH-DPAT.

How the study worked

Multiple approaches: vomiting studies in shrews (Suncus murinus) using nicotine, lithium chloride, and cisplatin as triggers; nausea studies in rats using conditioned gaping; microinjection into the DRN; in vitro receptor binding studies with brainstem membranes. 5-HT1A antagonists (WAY100135, WAY100635) were used to test the mechanism.

What this study cannot tell us

The study used animal models (shrews and rats), and anti-nausea effects in animals may not directly predict human response. The bell-shaped dose-response curve suggests dosing would need careful optimization. Conditioned gaping in rats is a validated but indirect measure of nausea.

How to read the evidence

Animal study with multiple models and clear mechanism identification; strong preclinical evidence but no human data.

When this study was published

Published in 2012. CBD anti-nausea research has continued, with growing interest in clinical applications for chemotherapy-induced nausea.

The bigger picture

While THC is already approved for chemotherapy-induced nausea (as Marinol/dronabinol), CBD offers a non-psychoactive alternative. This study mapped the precise neural pathway through which CBD works, providing a foundation for developing CBD-based anti-nausea treatments.

Questions still open

What is the optimal CBD dose for anti-nausea effects in humans? Could CBD be combined with existing serotonin-based anti-nausea drugs for enhanced effect? Why does CBD show a bell-shaped dose-response curve for 5-HT1A receptor modulation?

Common questions

How does CBD stop nausea?

This study showed CBD works by indirectly activating serotonin 5-HT1A receptors in a brainstem region called the dorsal raphe nucleus. This is interesting because many prescription anti-nausea drugs also work through serotonin pathways, though they target different receptor subtypes.

Is CBD better than THC for nausea?

They appear to work through different mechanisms. THC directly activates cannabinoid receptors, while CBD works through serotonin receptors. CBD has the advantage of being non-psychoactive. This study also found that low doses of CBD combined with a serotonin agonist produced synergistic anti-nausea effects, suggesting combination approaches could be effective.

Read the original research

Cannabidiol, a non-psychotropic component of cannabis, attenuates vomiting and nausea-like behaviour via indirect agonism of 5-HT(1A) somatodendritic autoreceptors in the dorsal raphe nucleus.

British journal of pharmacology, 165(8), 2620-34

View on PubMed ↗Publisher’s paper ↗

Citation

Rock, E M; Bolognini, D; Limebeer, C L; Cascio, M G; Anavi-Goffer, S; Fletcher, P J; Mechoulam, R; Pertwee, R G; Parker, L A. (2012). Cannabidiol, a non-psychotropic component of cannabis, attenuates vomiting and nausea-like behaviour via indirect agonism of 5-HT(1A) somatodendritic autoreceptors in the dorsal raphe nucleus.. British journal of pharmacology, 165(8), 2620-34. https://doi.org/10.1111/j.1476-5381.2011.01621.x