Nausea and vomiting often go hand in hand.
But they’re different. Nausea is an uncomfortable feeling in the upper stomach accompanied by the urge to vomit. Vomiting is the act of throwing up.
Causes of Nausea and Vomiting
There are many causes of nausea and vomiting – pain, stress and anxiety, problems in the digestive system, problems in the middle and inner ear, and head injuries affecting the base of the brain and/or the major arteries that supplies this area.
The regulatory centers for nausea and vomiting are located in the “Chemoreceptor Trigger Zone” or CTZ found in the medulla—this area is located at the base of the brain.
Medications, especially those used in chemotherapy, also induce nausea and vomiting because they can stimulate these regulatory centers in the brain as well as irritate the digestive system.
If a person is undergoing chemotherapy and experiencing nausea and vomiting, they also often have problems with loss of appetite and weight loss.
These symptoms are all problematic for a person who is trying to regain their health.
So how can nausea and vomiting be controlled?
Common medications for nausea and vomiting
There are several different over-the-counter (OTC) medications for nausea and vomiting as well as dietary approaches. These can include eating mild or bland foods, eating smaller meals or by using OTC medications like bismuth subsalicylate (i.e. Pepto-Bismol, Kaopectate), or antihistamines.
Prescription medications like ondansetron, hydroxyzine, prochlorperazine or metoclopramide can also be used to treat nausea and vomiting.
Side effects vary for each of these medications but are often relatively mild and temporary.
Rare but more serious side effects include dizziness, headache, confusion, increased anxiety, depression, stomach pain, diarrhea, problems with breathing, slurred speech, thirstiness, profuse sweating, vision problems.
However, medications whether OTC or prescription, don’t always work well in individual cases and some side effects can be significant enough that a person can’t take the medication. Cannabinoids may be an alternative solution.
Cannabinoids and how they work to reduce nausea and vomiting
There are at least two cannabinoids that may help control nausea and vomiting, tetrahydrocannabinol (THC) and cannabidiol (CBD).
THC appears to control nausea and vomiting by stimulating the CB1 receptors in the brain, especially the CB1 receptors found in the regulatory centers for nausea and vomiting1. Additionally, THC also stimulates the CB1 receptors in the gastrointestinal tract to reduce intestinal motility. Activating these receptors also improves appetite.
As you know, recreational marijuana users often consume large amounts of food and blame it on the “munchies”. Well, recreation aside, the “munchies” can be a remarkable thing for someone suffering from cancer.
CBD, however, appears to have different actions—it seems to reduce nausea and vomiting by acting on another set of receptors, those that bind serotonin1, 2. CBD, also appears to decrease the release of serotonin, reducing the irritability of the digestive tract and potentially affecting the CTZ.
Synthetic analogs of THC like nabilone (Cesamet) and dronabinol (Marinol) have been used to treat nausea and vomiting and to increase appetite2. Sativex which contains THC and CBD in a 1:1 ratio has also been used to control nausea and vomiting3. CBD may also increase the levels of the body’s natural endocannabinoids like anandamide by reducing it’s enzymatic degradation4.
You should also know, however, that chronic cannabis use is associated with something called “Cannabinoid Hyperemesis Syndrome”5. It is very rare and is usually associated with cannabis use rather than CBD6.
You might be wondering then, are THC and CBD safe to use for nausea and vomiting?
As is very often the case when it comes to THC and CBD, trials are currently in progress, but so far, the data indicates that “Cannabis use appears well tolerated, with few serious adverse effects reported7.” Another Phase II clinical study found that THC plus CBD significantly reduced nausea and vomiting after chemotherapy and that “most participants preferred cannabis extract to placebo8.”
Of course, there are precautions in using medical cannabis, too, as one study explains and should not be given to vulnerable populations like pregnant women, people with mental illness, adolescents, and people with heart, lungs, and immune system problems12.
Which cannabinoid works best for which symptom?
Both CBD and THC seem to work well to control nausea and vomiting, but according to the Handbook of Cannabis, written by Roger Pertwee, if you are going to treat nausea alone, Dronabinol (a synthetic THC and approved by the FDA and commonly referred to as Marinol) works best to control mild to moderately-severe chemotherapy-induced nausea.
However, Dronabinol doesn’t seem to work that well in controlling vomiting induced by the stronger chemotherapy drugs. This synthetic THC can also improve appetite and help with weight loss problems13. Unfortunately, Dronabinol also has side effects similar to THC. It can produce a “high”, it can cause paranoia, it can trigger mood changes and confusion, and it can increase anxiety.
Plus, Dronabinol can also cause nausea and vomiting, which is frustrating when you think about it because you’re using Dronabinol to control nausea and vomiting in the first place. Using THC alone to control nausea and vomiting would seem to be counterproductive because of its psychoactive effects.
Finally, you can only use Dronabinol by prescription.
CBD alone can be used—it may take some trial and error to find the best amount for you to take to decrease your nausea and vomiting—the general advice is to start low and go slow.
If you want to try a product with some THC, you can try the full spectrum products as they do contain some THC. If you live in a state where both “recreational” and medical cannabis are legal, you can also try to adjust the ratios of CBD and THC—usually between 2:1 CBD:THC and 1:2 CBD:THC. You can also combine these ratios with some dietary approaches—eg, eating blander foods and smaller amounts of food at each sitting.
The best ratio of CBD to THC for nausea may be outside that 2:1 to 1:2 range—you may need to try other combinations to find the best ratio for you. Some people do find that the best approach is the “old-fashioned” one—that is, smoking a joint. Here again, you may have to try different varieties and strains to find your best ratio. One advantage is that with the cannabis leaf, you can get the most of the entourage effect—the effect that is believed to follow by using the whole leaf.
More Research on THC and CBD
THC, although it does produce a “high,” can be very effective against nausea and vomiting induced by chemotherapy.
But what if THC and CBD are combined? In combination, CBD appears to reduce the intoxicating properties of THC and may be more effective than THC alone. 
As mentioned, Sativex, an oromucosal spray used in the treatment of multiple sclerosis that has a combination of THC and CBD at a ratio of 1:1 per spray, works well to control nausea and vomiting.3
If you’re interested in knowing the dosage and frequency, mean daily dose was about 5 sprays per day, with each spray containing 1:1 THC to CBD ratio or 2.7mg THC to 2.5mg CBD.
A mom will do anything for her child
Let me share with you a story I read.
Dr. Lester Grinspoon, a Harvard researcher who authored a book entitled “Marihuana Reconsidered,” had a son who was suffering from childhood leukemia.
One time at a dinner party, one of his colleagues mentioned that he knew of a patient who used cannabis to control chemotherapy-induced nausea.
He must have told the story to his wife, Betty, because she suggested that they find their son some marijuana.
But Dr. Grinspoon would not consider the idea because cannabis was illegal at the time.
Undeterred, Betty sought cannabis for her son and found some from one of her son’s friends.
After the next chemotherapy session, she gave the marijuana to her son.
The experiment was successful. The boy was relaxed, in a better mood, and wasn’t suffering from any nausea.
Even Dr. Grinspoon noted the huge difference.
He remarked that, without marijuana, his son would have been in bed dealing with nausea and vomiting.
But on that day, not only was their son better, but he had an appetite that he even requested to stop and get a sandwich before going home.
Using THC and CBD for nausea and vomiting control is worth a try
Nausea and vomiting can be very debilitating, especially in people recovering from cancer and chemotherapy side effects.
If you’re going to use THC and CBD to control these symptoms, it is generally recommended that you can start with low dosages of equal parts THC and CBD and then slowly titrate or change the dosage until you find one that works for you. Most people find that a range of ratios of CBD and THC range between 2 CBD: 1 THC and 1 CHD: 2 THC. The absolute amount of THC rarely is higher than 10 mg.
But if you find you’re sensitive to THC or don’t like its psychoactive effects, remember that medical cannabis is a therapy that you can personalize.
The important thing is for you to find a balanced ratio of THC and CBD that will work for you.
But remember—before you buy THC and CBD products, always check the reputation of the manufacturer/provider.
A manufacturer using good practices will be producing a full plant, cannabinoid and terpene rich cannabis oil.
You should be able to get in contact with the manufacturer and directly ask them questions. Communication is very important.
A good provider will show you recent lab results of the product to ensure it is free from toxins, mold, and pesticides.
After all, this is medicine. The products must be clean and safe for a sick person to use.
It's always a good idea to read reviews before buying, and while you’re at it, do check the FDA's site for information on some of these providers.
1Parker, L. A., Rock, E. M., & Limebeer, C. L. (2011). Regulation of nausea and vomiting by cannabinoids. British journal of pharmacology, 163(7), 1411–1422. https://doi.org/10.1111/j.1476-5381.2010.01176.x
2Sharkey, K. A., Darmani, N. A., & Parker, L. A. (2014). Regulation of nausea and vomiting by cannabinoids and the endocannabinoid system. European journal of pharmacology, 722, 134–146. https://doi.org/10.1016/j.ejphar.2013.09.068
10Walker LA, Koturbash I, Kingston R, ElSohly MA, Yates CR, Gurley BJ, Khan I. Cannabidiol (CBD) in dietary supplements: Perspectives on science, safety, and potential regulatory approaches. Journal of Dietary Supplements. 2020 Sep 2;17(5):493-502.
11Bergamaschi MM, Queiroz RH, Zuardi AW, Crippa JA. Safety and side effects of cannabidiol, a Cannabis sativa constituent. Curr Drug Saf. 2011 Sep 1;6(4):237-49. doi: 10.2174/157488611798280924. PMID: 22129319.
12Sachs J, McGlade E, Yurgelun-Todd D. Safety and Toxicology of Cannabinoids. Neurotherapeutics. 2015 Oct;12(4):735-46. doi: 10.1007/s13311-015-0380-8. PMID: 26269228; PMCID: PMC4604177.
13A. (n.d.). Marijuana and Cancer. Retrieved January 06, 2021, from https://www.cancer.org/treatment/treatments-and-side-effects/complementary-and-alternative-medicine/marijuana-and-cancer.html
14Madras BK. Tinkering with THC-to-CBD ratios in Marijuana. Neuropsychopharmacology. 2019 Jan;44(1):215. https://www.nature.com/articles/s41386-018-0217-3