Medical Cannabis and Nausea and Vomiting
Nausea is the feeling of sickness and wanting to vomit, though nausea does not always lead to vomiting. Nausea and vomiting are not always harmful but are common signs or side effects of many health problems, treatments and medications. Medical cannabis often contains several compounds with anti-emetic (anti-nausea and anti-vomiting) properties.
What is Nausea?
Nausea is another condition that is more often a symptom of another underlying problem than an issue in and of itself (although a condition called cyclic vomiting syndrome, or CVS, does exist). Nausea does not always lead to vomiting, but the causes and treatments are often the same.
Headaches and migraines can cause nausea, as can various drugs and medications. This includes treatments such as chemotherapy; fainting and dizziness; exposure to heat; stomach infections such as norovirus; GI problems such as gastroesophageal reflux disease (GERD); low blood sugar; motion sickness or any loss of balance resulting from disturbance of the inner ear; depression; anxiety; or seeing, smelling and/or tasting something particularly vile. There are likely to be many other triggers as well.
Dopamine (D2) receptors, serotonin (5HT3) receptors, neurokinin receptors (NK1), antihistamine, acetylcholine and TRPV1 (vanilloid) receptors all play a role in causing the sensation of nausea. The group of receptors responsible for nausea and vomiting are often referred to as the “chemoreceptor trigger zone.”
Brief Summary of Current Treatments
Medications used to ease nausea and vomiting are referred to as “anti-emetics.” Examples include:
- Bismuth subsalicylate (Pepto-Bismol, BisBacter) is an antacid elixir medication used to treat temporary discomforts of the stomach and gastrointestinal tract.
- 5-HT3 receptor antagonists that block serotonin receptors, e.g., dolasetron (Anzemet) and granisetron (Kytril, Sancuso): These are usually prescribed for post-operative and cytotoxic drug nausea and vomiting.
- Dopamine antagonists, which block dopamine receptors on the brain stem, e.g., domperidone (Motilium) and olanzapine (Zyprexa): These are usually prescribed for nausea and vomiting associated with chemotherapy, radiation sickness, opioids, cytotoxic drugs and general anesthetics.
- NK1 receptor antagonists such as aprepitant (Emend) and rolapitant (Varubi)
- Antihistamines (H1 histamine receptor antagonists) such as diphenhydramine (Benadryl), promethazine (Pentazine, Phenergan, Promacot) and Dimenhydrinate (Gravol, Dramamine): These are often prescribed for motion sickness, morning sickness in pregnancy and opioid-induced nausea.
- The antidepressant mirtazapine (Remeron), which is also an antihistamine
- Synthetic cannabinoids like dronabinol, levonantradol and nabilone, which are structurally similar to delta-9-THC (but more potent), may be prescribed for managing nausea and vomiting associated with chemotherapy.
Non-medical interventions for less chronic or severe nausea and vomiting include fresh air, sipping on cold drinks and healthy, well-planned meals at fixed times of the day. Those who have food intolerances may need a change in diet. Ginger, cloves, peppermint and Devil’s Claw are common herbal remedies.
How Might Medical Cannabis Help?
Anti-emetics are generally tolerated well, but they can have side effects such as constipation or diarrhea, headache, fatigue, malaise, dizziness, light-headedness, blurred vision, dry mouth or photosensitivity. Some people may also find some classes of anti-emetics intolerable or ineffective. Medical cannabis could be helpful in reducing or replacing anti-emetic use, or as an effective alternative in the case of treatment resistance. Many find plant-derived cannabinoids (phytocannabinoids) much more tolerable compared to dronabinol and nabilone.
Cannabis also contains several compounds that have anti-emetic properties, including tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabichromene (CBC). THC, CBD and CBC exert their anti-emetic properties via interaction with cannabinoid receptor 1 (CB1) and serotonin receptor 5-HT3.
Moreover, as phytocannabinoids and terpenes affect multiple receptors and have a wide range of effects, cannabis can be utilized as an analgesic, anti-inflammatory, antidepressant and anticonvulsant as well as an anti-emetic. This can help reduce the intake of other medications that may contribute or cause nausea and vomiting.
It should be noted that overconsumption of THC and cannabigerol (CBG) may induce nausea and/or vomiting in some. Moderate-to-high doses of CBG may oppose the anti-emetic effects of THC and CBD.
- THC has significant anti-emetic properties.
- CBD also has anti-emetic properties.
- CBG may also be useful for nausea, but may also oppose the anti-nausea effects of THC and CBD in moderate to high doses.
- The acidic cannabinoids tetrahydrocannabinolic acid (THCA or THCa) and cannabidiolic acid (CBDA or CBDa) may also have anti-emetic properties.
Cannabinoid Ratios (THC:CBD)
The following THC:CBD ratios may be useful for managing nausea and vomiting:
Terpenes and Terpenoids
Effective Ways of Taking Medical Cannabis for Nausea
Routes of Administration
Although CBD-rich formulations may be useful for managing nausea and vomiting, there is evidence that THC has greater anti-emetic effects. However, the two together synergize and may increase each other’s anti-emetic properties via the entourage effect. Combining THC and CBD may also help reduce the likelihood of THC triggering nausea and vomiting.
Although excessive THC, CBG, limonene and quercetin may trigger nausea and vomiting, they are rarely in high enough concentrations in cannabis to do so. Moreover, in low-to-moderate doses, they can help alleviate nausea and vomiting, so they don’t necessarily need to be avoided entirely.
- Inhaling cannabis (preferably via a high-quality vaporizer or inhaler) can provide quick relief, as cannabinoids are passed directly through the lungs and into the bloodstream.
- Tincture (sublingual) ingestion may be ideal for longer-term relief from nausea. The cannabis flavor may also help provide quicker relief.
- Edibles can provide long-term relief, and ingesting THC has more potent effects compared to other administration routes. Low-to-moderate doses of THC may be better when ingesting cannabis in order to reduce the chances of an adverse side effect.
- Suppositories may be useful for those with health problems affecting their digestive system.
What are the Pros and Cons of Taking Medical Cannabis for Nausea?
- Some anti-emetic medications currently prescribed have many adverse side effects, whereas cannabinoids have much fewer by comparison.
- Cannabinoids may well work for rare conditions such as CVS.
- Low doses of CBG and low-to-moderate doses of CBD and THC have anti-emetic effects.
- Medical cannabis may be particularly useful for nausea associated with cancer and chemotherapy.
- Medical cannabis helps alleviate insomnia, chronic pain, appetite loss or low mood accompanying nausea and vomiting.
- Cannabinoid hyperemesis syndrome (CHS) is a rare possibility in those who have been using cannabis long-term. CHS is characterized by nausea, vomiting and compulsive bathing after cannabis use. Stopping cannabis use and hot showers can stop CHS. CHS should not be confused for cyclic vomiting syndrome (CVS), which has similar symptoms.
- Too much THC may trigger nausea or vomiting in high doses while blocking it in lower or more moderate doses.
- CBG is a cannabinoid that may also work against the anti-emetic effects of CBD when in moderate or high doses (but is anti-emetic in low doses).
- High doses of the flavonoid quercetin may cause GI upset and nausea.
- Excessive limonene intake is associated with nausea and vomiting.
Useful Anecdotal Information
“WBUR: How could a cancer patient benefit from using cannabis?
Dr. Jordan Tishler: Nausea and vomiting, appetite issues, fatigue, anxiety, insomnia — those sorts of things that are associated either with cancer or chemotherapy, those things are very well treated with cannabis.” Source: Weintraub, Karen, ‘Q&A With A Cannabis Clinician: What Cancer Patients Should Know’ January 10. 2018
‘Can cannabis ease chemotherapy side effects?’, Al-Jazeera English
Scientific Data Overview and Studies
- Total Studies = 89
- Positive Studies = 70
- Inconclusive Studies = 9
- Negative Studies = 10
- 54 Meta-Analyses (37 positive, 7 inconclusive, 10 negative); 6 Animal Studies (all positive); 20 Double-Blind Human Trials (19 positive, 1 inconclusive); 9 Human Trials (8 positive, 1 inconclusive)
- 24 studies include CBD (20 positive, 4 inconclusive); 15 studies include THC (15 positive, 3 inconclusive); 1 study includes CBG (negative). 6 studies include CBDA (all positive); 1 study includes delta-8-THC (positive); 2 studies include THCA (both positive); 8 studies include a 1:1 THC:CBD ratio (all positive)
- No. of Leafwell Patients (2022) = 1,515
- Possible Overall Efficacy: High
Quotes from Studies and Scientists
“Fifty-five patients harboring a variety of neoplasms and previously found to have severe nausea or emesis from antitumor drugs were given antiemetic prophylaxis in a double-blind, randomized crossover fashion. delta 9-Tetrahydrocannabinol (THC), prochlorperazine, and placebo were compared. Nausea was absent in 40 of 55 patients receiving THC, in 8 of 55 patients receiving prochlorperazine, and in 5 of 55 in the placebo group. THC appeared to be more efficacious in controlling the emesis associated with cyclophosphamide, 5-fluorouracil, and doxorubicin and less so for nitrogen mustard and the nitrosourea. THC appears to offer significant control of nausea in most patients and exceeds by far that provided by prochlorperazine (P less than 0.005).”
L. E. Orr and J. F. McKernan, ‘Antiemetic effect of delta 9-tetrahydrocannabinol in chemotherapy-associated nausea and emesis as compared to placebo and compazine’. J Clin Pharmacol. Aug-Sep 1981;21(S1):76S-80S. doi: 10.1002/j.1552-4604.1981.tb02578.x
“Considerable evidence demonstrates that manipulation of the endocannabinoid system regulates nausea and vomiting in humans and other animals. The anti-emetic effect of cannabinoids has been shown across a wide variety of animals that are capable of vomiting in response to a toxic challenge. CB1 agonism suppresses vomiting, which is reversed by CB1 antagonism, and CB1 inverse agonism promotes vomiting. Recently, evidence from animal experiments suggests that cannabinoids may be especially useful in treating the more difficult to control symptoms of nausea and anticipatory nausea in chemotherapy patients, which are less well controlled by the currently available conventional pharmaceutical agents.”
Parker LA, Rock EM, Limebeer CL. ‘Regulation of nausea and vomiting by cannabinoids’. Br J Pharmacol. 2011;163(7):1411-1422. doi:10.1111/j.1476-5381.2010.01176.x
“Early results of a landmark trial involving 80 patients at the Chris O’Brien Lifehouse hospital show that cannabis capsules were better than placebo at improving symptoms.
“An extra one in 10 people had control of nausea and vomiting, so it had improved from 14 per cent to 25 per cent,” said Associate Professor Peter Grimison, a medical oncologist at Chris O’Brien Lifehouse.
Gabrielle Boyle, ‘Patients prefer medicinal cannabis in chemotherapy trial’, 9News, Sep 18, 2020
Although there are several effective and well-tolerated anti-emetics available over the counter (OTC) and available for prescription, not all people find such medications effective. Patients undergoing chemotherapy may find that their nausea and vomiting are treatment-resistant. Medical cannabis could be an excellent alternative or adjunct to the drugs currently prescribed.
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- Cannabis and its Adverse Effects, Cannabis Dependence and Cannabinoid Hyperemesis Syndrome (CHS)
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