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.
Preamble: What is CBD?
Cannabidiol (CBD) is a chemical from the cannabis plant, belonging to the class known as cannabinoids. Unlike its cousin THC, CBD does not make you high.
CBD has gained significant medical and scientific interest in the recent years because of its therapeutic properties. CBD can completely eliminate seizures in some suffering from epilepsy. Countless anecdotal reports list improvements in areas such as:
- Anxiety and stress
- Social disorders
- General pain
- Specific conditions such as arthritis, epilepsy, and Crohn’s disease (just to name a few)
- Nausea and vomiting due to motion sickness, illness, ingestion of toxins, anxiety, CINV, and more
There is even a significant interest in the field of cancer, as reported by the American Cancer Society.
However, CBD is not a cure-all snake oil. While it may not work for everyone in these areas, it undoubtedly affects nearly the entire body. For more information on this, refer to the following guides:
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.
Another potent activation center is the gastrointestinal tract itself. Specifically, vagus or sympathetic nerves throughout the tract can send signals if irritation is detected. These nerves are rich in 5-HT3 serotonic neuroreceptors, which send the actual signals to the area postrema after being activated. The most common antiemetics include 5-HT3 antagonists, such as Ondansetron (Zofran). These dampen or completely block the activation of the 5-HT3 receptors, significantly reducing nausea caused by gastrointestinal distress. This can be extremely helpful in cases such as norovirus infection, the most common form of gastroenteritis (stomach flu).
Such signals can be sent from other organs as well, albeit typically weaker. These include the heart and bile ducts. Another common trigger is from extramedullary centers of the brain, or areas not in the medulla oblongata. These are typically sensory-based, and explain why nausea can be felt as a result of vile odors, or motion sickness.
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.
CBD Oil can Help CINV
Rats and shrews aren’t the only living organisms affected by CBD’s antiemetic properties. In a 2010 report, cannabis extract was used in a double-blind study involving chemotherapy patients, specifically those affected by chemotherapy induced nausea and vomiting, or CINV. This is one of the most undesirable yet obnoxiously consistent side effects of chemotherapy.
With many chemo patients describing the rapid onset CINV experience as overpowering, a plethora of antiemetics have been produced to combat the condition. The 5-HT3 antagonists (-setrons) are the most common, those being:
- Ondansetron (Zofran)
Furthermore, the corticosteroid dexamethasone is somewhat effective in treating CINV. Many other drug classes treat CINV:
So, pretty much everything. Nothing quite compares to cannabinoids, however. Cannabinoids such as CBD, CBDa, and THC prevent serotonin and dopamine neurotransmission at the receptor sites associated with CINV, such as 5-HT3.
As you can see, there is strong overlap with the rat and shrew studies in terms of cannabinoid effects on nausea.
Synthetic Cannabinoids for Nausea Relief
A number of synthetic cannabinoids (not to be confused with K2/spice) have been synthesized to treat nausea. These are typically very effective, but can carry side effects. Namely, these are nabilone and dronabinol, both of which are chemically similar to THC. Both have been approved by the FDA for the treatment of CINV, and have been demonstrated to be very effective.
A Digression on Cannabinoid Hyperemesis Syndrome
Cannabinoid Hyperemesis Syndrome, or CHS, is a paradoxical and poorly understood affliction sometimes induced in long-time cannabis users. Symptoms include:
- Acute nausea and vomiting
- Gastrointestinal discomfort
- Compulsive bathing
Note that this is not to be confused with terms such as “greening out”, which involve consuming too much THC at once.
Considering the widespread use of cannabis for treating symptoms such as chronic nausea, CINV, and morning sickness, the very existence of CHS seems absurd. Despite this, a number of studies have shown that CHS can exist in long-time cannabis users, typically resolving following cessation.
Should I Worry About CHS?
If you are new to cannabis, or looking into it to treat nausea, the answer is an emphatic no. It is extremely unlikely to be inflicted with CHS:
- CHS only occurs in long-term users
- It only occurs in THC users
- It is extremely rare to begin with
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.