CBD for Nausea:
Can it Help? October 2024

Nausea Overview

The feeling of nausea is a commonly encountered symptom with a wide range of possible biological and psychological causes: ⁵

• Infectious (e.g., food poisoning or gastroenteritis)
• Medication-related (e.g., from chemotherapy or antibiotics)
• Central Nervous System (e.g., from migraines, meningitis, or seizures)
• Psychiatric (e.g., anxiety, depression, eating disorders)
• Labyrinthine (e.g., motion sickness or vertigo)
• Endocrinological or metabolic (e.g., pregnancy, hormonal imbalances)
• Gastrointestinal (e.g., from a bowel obstruction, ulcer, or pancreatic diseases)

While the feeling of nausea symptoms typically leads to eventual vomiting, this doesn’t always have to be the case.

In fact, most people report that nausea is more common and disabling than vomiting because the feeling can last for an extended period of time. ⁶ In a population study based on 62,651 individuals, 12.5% reported nausea being a “minor or major complaint” in the last 12 months. ⁷

Evolutionary biologists believe nausea may have evolved as a natural protective mechanism and this reflex can be found in many different animal species. ⁸

Nausea and vomiting can trigger the expulsion of any ingested toxins (e.g., drugs, alcohol) or contaminated food items containing toxic levels of certain bacteria, poisons, or viruses. ⁹ By emptying the contents of the stomach and upper intestinal tract, the body may be able to prevent or divert the possible dangers stemming from these toxins.

However, not all cases of nausea are warranted, and nausea can be inadvertently triggered by a variety of unrelated conditions.

For instance, a sensory disconnect between what we see and what we feel — commonly referred to as motion sickness — can trigger unnecessary nausea. Likewise, unrelated conditions such as migraines and anxiety can also be a trigger.

Sometimes, nausea can also occur as a side-effect of certain medications such as chemotherapy for cancer treatment. This often makes managing an existing condition even more difficult.

Nausea and the Brain

Researchers are continuing to shed light on the complex mechanisms that underlie how nausea and the brain are related. What they do know is that the mechanisms encompass our psychological state, central nervous system, autonomic nervous system, endocrine system, and gastric dysrhythmias (conditions that affect normal stomach contraction and digestion). ⁵

Stimuli giving rise to nausea and vomiting originate from various areas including the gut, our sense of balance, and the chemoreceptor trigger zone – an area of the brain (part of the medulla oblongata) that receives inputs from blood-borne drugs or hormones which ultimately initiate vomiting.

In addition to the chemoreceptor trigger zone, the medulla oblongata is an area of the brain that is particularly important for other reasons. Many of the signals generated that seem to lead to nausea (e.g., from emotional responses, toxin-related, motion-induced) are relayed to the nucleus tractus solitaries, which is also part of the medulla oblongata.

From here, the signals are then passed on to other areas such as the autonomic nervous system (i.e., where involuntary processes are regulated like breathing, heart rate, and digestion), and ultimately give rise to that uncomfortable feeling. ⁵

Importantly, researchers propose that each individual has a threshold for nausea that changes minute by minute, calling it a “dynamic threshold”. They say that the threshold depends on the interaction between an individual’s inherent factors and some more changeable factors like psychological states of anxiety, anticipation, expectation, and adaptation.

The combination of all these factors is what they propose explains the variability of nausea between individuals and for a single individual over time.

Cannabis and the Endocannabinoid System

A major signaling network involved in many aspects of our bodily function is the endocannabinoid system (ECS). ¹

“Endocannabinoids” are naturally produced chemicals in the human body that play a role in regulating a variety of biological responses — including shutting down feelings of nausea and vomiting.

Cannabinoids such as THC and CBD can mimic these natural “endocannabinoids” and similarly reduce nausea.

Delta-9-tetrahydrocannabinol (THC) is the principal psychoactive component of cannabis and when consumed can cause feelings of “euphoria” or “high” that are typically associated with cannabis. ¹⁰

CBD, or cannabidiol, is non-psychoactive and does not lead to those same sensations.

Both THC and CBD can interact with two different types of cell receptors that are part of the ECS: CB1 and CB2.

How Cannabinoids Block Nausea and Vomiting

Researchers have found CB1 receptors distributed across multiple parts of the brain including areas that regulate nausea and vomiting. ¹¹

There’s also evidence that CB1 receptors may be present in the gut where nausea and vomiting may be triggered upon detecting possible contaminants or toxins. ¹²

To date, most studies have examined both nausea and vomiting together. This is largely because nausea is a subjective condition and it can be difficult to measure just how nauseous a patient is compared to another.

Distinguishing the two is even harder in animals because it’s not always obvious whether an animal is or isn’t nauseous.

While most studies focus on vomiting as an indicator for nausea, it’s important to note that nausea can occur without the need to vomit and there are likely different mechanisms that control nausea that researchers haven’t yet identified.

But based on animal studies so far, nausea and vomiting from food poisoning may be signaled by the release of the serotonin hormone in the small intestines. This signaling occurs after the animals have ingested the “bad bacteria” that commonly lead to digestion issues. The researchers then found that this serotonin signal from the gut and the follow-up vomiting could be reduced by activating the CB1 receptors. ¹²

Other animal studies have similar findings, showing that THC can bind CB1 receptors directly and may block nausea and vomiting through this effect. ¹³

CBD can also prevent the breakdown of natural endocannabinoids — such as anandamide — which can help the body maintain stimulation of the CB1 receptors for longer and reduce nausea and vomiting.

To further understand CB1’s important role, researchers conducted studies on humans and found that some individuals may have a naturally less responsive ECS when experiencing nausea and vomiting from motion sickness. For instance, a 2010 study of 21 human volunteers found that those who were more likely to experience motion sickness tend to have less CB1 receptor activity. ¹⁴ ¹⁵

In test-tube cell studies, researchers found that THC and anandamide are capable of blocking serotonin signaling directly by binding certain serotonin receptors and that CBD can also directly bind to other serotonin receptors to affect serotonin signaling. ¹⁶ These studies show the possibility that cannabinoids could additionally be reducing nausea and vomiting through signaling pathways outside of CB1 receptor binding.

Cannabinoids for Treating Nausea

There are three cannabinoids currently approved by the FDA for the pharmaceutical market, two of which – Dronabinol and Nabilone – can be used to treat serious cases of nausea and vomiting (e.g., chemotherapy-induced nausea and vomiting).

Both drugs are synthetic versions of THC and are administered in pill form. There are no concrete guidelines for dosing, but both are typically prescribed at doses between 10 mg to 50 mg daily.

THC has been used for treating nausea since 1985 and its efficacy has been validated by over a dozen clinical studies and controlled double-blind trials beginning in the 1970s. ¹ ⁴

In one of the first randomized, double-blind, and placebo-controlled studies — a gold standard in clinical research — 40 out of 55 patients experiencing “severe nausea” reported THC eliminating their nausea and vomiting completely (7mg of THC per square meter of the body surface, taken every four hours for four doses). ¹⁷

By contrast, only 5 patients in the placebo group reported any reduction in their nausea and vomiting.

A 2001 review of 30 different randomized and controlled human trials with a total of 1,366 patients found that across all clinical studies, THC or a synthetic THC alternative was always more effective than placebos and other anti-vomiting medication in treating nausea and vomiting from chemotherapy and anti-tumor drugs. ¹⁸

A more recent 2007 double-blind placebo-controlled study with 61 cancer patients further found that synthetic THC was just as effective in preventing nausea and vomiting as Ondansetron (also known as Zofran) — a commonly used anti-nausea prescription medication. ¹⁹

Unfortunately, the use of CBD alone has not yet been investigated to the same degree in treatment for nausea. The only completed clinical trials involving CBD examine a blend of 1:1 THC and CBD.

In a 2010 randomized, double-blind, and placebo-controlled pilot study in Spain, 16 participants experiencing chemotherapy-induced nausea and vomiting were given either a THC and CBD nasal spray or a placebo spray. ²⁰

These patients could use the spray as needed for up to 4 days after their chemotherapy appointment. Participants inhaled an average of 12.9 mg THC and 12 mg CBD per day.

For patients using the THC and CBD spray, 57% reported no nausea and 71% reported no vomiting as compared to just 22% in both categories for patients using the placebo. Only one participant had to be removed from the study after using the spray and experiencing increased anxiety. ²⁰

Currently, the New South Wales government is funding the “largest, most definitive” clinical trial to further evaluate the use of CBD and THC in preventing chemotherapy-induced nausea and vomiting.

In the phase II crossover randomized controlled trial, 81 participants were given either placebo capsules or oral capsules containing both THC and CBD (2.5mg each) to be taken three times a day. ²¹ ²²

Although 31% of participants experienced some side effects including sedation and dizziness, 83% of participants still preferred using the cannabis extract over a placebo.

Potential Side Effects

While clinical trials are still lacking when it comes to CBD for nausea, THC has already been well documented as a potent treatment option for nausea, and laboratory studies suggest that CBD may achieve a similar effect.

CBD is also remarkably safe when used properly, however, there are several common possible side effects to be aware of: ²³

• Dry mouth
• Dry or itchy eyes
• Headaches or light-headedness
• Increased anxiety or paranoia
• Sleepiness or lethargy
• Diarrhea
• Changes in appetite or weight

Both THC and CBD can also interfere with certain prescription drugs. It is best to consult with a physician if you plan on trying a cannabinoid alongside other medication.

Heavy chronic use of cannabis, especially in young people, has also be observed to cause recurrent nausea and vomiting in a condition called “cannabinoid hyperemesis syndrome.” The exact cause is unclear, but this condition has only been observed in a very small number of individuals after almost daily long-term use of cannabis. ²⁴

Trying CBD to Treat Nausea

Overall, cannabinoids have shown to offer a comparable benefit to alleviating nausea and vomiting similar to pharmaceutical anti-nausea medications.

Although THC remains the best studied in controlled trials, the effects of CBD and hemp oil can likely impart similar anti-nausea benefits by interfering with the breakdown of natural endocannabinoids and by blocking serotonin receptors. Full-spectrum hemp extract will likely work best thanks to the entourage effect.

When trying CBD oils for nausea, it’s best to follow the dosage recommendations on the CBD product — typically starting at between 10-15 mg a day.

Your body weight, genetics, and the type of CBD product you use can all affect how you respond to CBD and the dosage required to treat your nausea or vomiting. ²⁵ ²⁶

While some research suggests that even doses up to 1,500 mg a day can be well-tolerated, depending on your body weight general recommendations fall between 30-75 mg for people between 100 to 250 lbs. ²⁷

Because higher doses of full spectrum CBD will inevitably increase the likelihood of side effects. It’s best, to begin with, a low dose and try going up slowly until you settle on an amount that helps relieve your symptoms.