More human CBD trials are needed to understand its health benefits

It is common knowledge that CBD oil is an excellent phytocannabinoid infusion, treating various afflictions ranging from seizures to inflammation. However, did you know that studies show it is one of the most potent antiemetics? This means it has exceptional anti-nausea and anti-vomiting properties.

This article will cover the little-known science behind vomiting, as well as survey the existing antiemetics, and then describe CBD’s properties as an antiemetic in full detail.

Topics such as CINV (chemotherapy induced nausea and vomiting), gastrointestinal irritation mediated by 5-HT3 receptors, and 5-HT1A, a neuroreceptor which is adept at preventing nausea, will be discussed.

The Physiology of Nausea

The induction of nausea and vomiting is a complex physiological process. While there are several possible triggers, almost all forms of vomiting come down to the area postrema being activated. This is a part of medulla oblongata, a part of the brain dedicated to performing autonomous tasks.

The brainstem contains a number of anatomical nausea-inducers. or vomition centers. The most frequently discussed of these is the aptly-named chemoreceptor trigger zone. Unlike other neural systems, this part of the brain is not activated by electrical signals. Rather, chemical abnormalities detected in the blood set off the chemoreceptor trigger zone. It is what causes illness after poisoning, emetic drug intake, and alcohol intoxication.

What Does CBD Have to do With it?

It all comes down to a unique neuroreceptor known as 5-HT1A. This receptor mediates inhibitory neurotransmission among 5-HT receptors, meaning it dampens signals that are too excited. 5-HT1A is the most widespread 5-HT receptor. It is found nearly all over the central nervous system.

So how does CBD come into play? It has been found to be an indirect agonist of the 5-HT1A receptors, meaning by some mechanism, it activates these receptors. 5-HT1A receptors do not just reduce the vomition signals. When activated, they also:

  • Repress social anxiety
  • Decrease impulsivity and drug-seeking behavior
  • Prolong REM sleep
  • Decrease aggression

5-HT1A isn’t the only receptor involved, however. CB1 and CB2 receptors also have some effect over nausea in studies, but the mechanism is not exactly known. These receptors are directly activated by CBD and other cannabinoids. These receptors have been identified in the gastrointestinal tract and are theorized to have some connection to the area postrema, including nausea and emesis regulation.

Studies Showing Cannabis and CBD Help Nausea

An old 2002 study published in Neuroreport reported the first direct  correlation between CBD administration and nausea reduction. Rats administered with an emetic drug (which only makes them nauseous, as rats are unable to vomit) were also administered CBD, and it was found that any behavior indicating nausea was effectively eliminated, or strongly inhibited.

CBD isn’t the only cannabinoid found to act as an antiemetic, however. In 2013, a study published in the British Journal of Pharmacology found that a specific cannabinoid (cannabidiolic acid, or CBDa) significantly reduced nausea-based behavior in rats, even greater than the effect CBD has had.

The rats were administered emetic toxins, and it was later discovered that the CBDa had enhanced the activity of the rat’s 5-HT1A receptors, implying that this mechanism led to the decrease of their nausea-induced behavior.

Since rats can’t vomit as they lack a gag reflex (they can only have nausea), the experiment was repeated in shrews, which can vomit. It was a direct success, significantly decreasing the vomiting which occurred in the shrews.

Cannabigerol (CBG) and delta-9-tetrahydrocannabinol (THC) are other cannabinoids found to decrease nausea. In fact, when THC and CBDa were mixed in one study, an entourage effect of sorts was found. This led the researchers to conclude that the combination of THC and CBDa at sub-threshold doses was an effective antiemetic, and could be used for therapeutic purposes.

The Verdict: Does Cannabis Help Nausea?

YES! Countless studies, in both animals and humans, have demonstrated a large degree of success in treating nausea and vomiting, primarily through the 5-HT1A, CB1, and CB2 receptor activations caused by different cannabinoids including CBD, THC, CBDa, and CBG.

Research into this is only beginning, however. Cannabis contains over 100 cannabinoids, and we have only studied four of them for nausea specifically.

Perhaps with the advent of new breakthroughs in cannabis, such as the possible discovery of the CB3 receptor, and with more support and funding towards cannabis as a whole, we could put an end to unneeded nausea altogether.