Let's face it. We've all been there, hunched over the porcelain throne, heaving and whimpering like a cat with a furball problem. Vomiting is a very exhausting process. When it is happening, it will have your mind's full attention. You can't help it. It is like muscles you didn't know you had are now contracting in unnatural and unholy ways. Vomiting, or "emesis," as doctors like to call the involuntary emission of food back out the wrong way, is usually preceded by a period of nausea. It's the body's way of warning you of an impending, undignified bathroom visit. Nausea symptoms include paleness, enhanced salivation, sweating, and an increased heart rate.
Several remedies help reduce both nausea and vomiting. In that context, cannabis has been effectively used as a treatment for centuries.
For example, cannabis can be prescribed to offset chemotherapy-induced nausea while also stimulating appetite. This article will give you an introduction into the mechanisms behind nausea and how cannabis can be used therapeutically. It works well, although it is essential to note that there are some circumstances where prolonged cannabis consumption itself can cause vomiting and nausea and might not be advisable. First, let's understand what nausea actually is.
There are a diverse array of disorders involving a variety of pathophysiological processes that can cause nausea. Most cases of nausea and vomiting are acute, meaning they last for seven days or less and are transient. Typical causes can be infections, anatomic, mechanical trauma, or medication side effects. Chronic nausea and vomiting last for four weeks or longer. In extreme cases, symptoms can be present for more than six months. The vast majority of chronic nausea-related medical literature is written around the context of a condition called "gastroparesis." Gastro- derived from the Greek word for "stomach" and -paresis meaning "partial paralysis." Gastroparesis sounds scary but is very common. In essence, it describes the delayed emptying of the stomach's content during the digestive process. Delayed emptying leads to an accumulation of undigested food in the stomach, triggering nausea and vomiting to emit the food back up the way it came.
Aside from gastroparesis, there are many other reasons why one would experience nausea and vomiting. Vomiting is controlled by a complex series of events involving multiple organs, such as the heart, throat (oropharynx), gastrointestinal tract, diaphragm, abdominal wall muscles, the cerebral cortex of the brain, and more. The conditions that can trigger nausea and vomiting mirror this complexity. Basically, nausea and vomiting can be triggered via multiple pathways along the chain from the stomach to the muscles and afferent nerves connecting the whole apparatus to the brain. The brain's emetic center (vomiting center) interprets those stimuli and sends out instructions via efferent nerves to the various muscles facilitating the vomiting process. The current view is that if afferent pathways are only mildly stimulated, you get nausea; if there is intense stimulation, vomiting occurs. However, to simplify things, one can categorize the causes of nausea and vomiting into two groups:
- Gastrointestinal causes
- Non-gastrointestinal causes
"Gastrointestinal" means it directly involves the stomach and the intestines, like with gastroparesis. Conversely, "non-gastrointestinal" means the cause for the condition lies elsewhere. For example, the vestibular organ of the inner ear, which is responsible for our sense of balance (motion sickness), some neurological disorders (Parkinson's), or nausea-inducing medication like chemotherapy (CINV).
Dampening nausea with cannabis
The cannabinoid receptors of the endocannabinoid system can be found throughout the body at multiple tissues responsible for digestion, signal transduction of nausea triggers to the brain, as well as within the brain's emetic center. The cannabinoid receptors are found on tissue-resident cells, immune system cells, and synaptic connections between nerves. Consequently, the endocannabinoid system can modulate cells along this entire chain of the afferent pathways responsible for communicating nausea and pain from the peripheral regions of the body to the brain. In the brain, they can also affect the perception of pain and nausea while also dampening the efferent paths from the brain to the nerves and muscles involved in the vomiting process. These multiple points of action for the endocannabinoid system help explain why pain & nausea mitigation is by far the most successful and popular use case for medical cannabis. The phytocannabinoids act as agonists on cannabinoid receptors. In other words, they bind to the receptors of the endocannabinoid system and activate them. This has a multitude of effects on the digestive system. For one, they mimic the effect of gastroparesis, so the emptying of the stomach is delayed.
However, while gastroparesis usually leads to nausea, this does not appear to be the case when it is induced by phytocannabinoids. Cannabis also reduces the intestine contractibility and movement (peristalsis), as cannabinoid receptors can be found in the submucosal and myenteric nerves that control the circular and longitudinal muscle of the intestinal wall. Overall transit of food through the intestine and colon is delayed. In a nutshell, cannabis slows the digestive system down. It suppresses intestinal inflammation and relaxes the transmission of nausea triggers to the brain. In the brain, cannabis affects the perception of nausea and dampens the efferent nerves and muscles responsible for carrying out a vomiting reaction.
Dronabinol vs. inhaled cannabis
Dronabinol is the #1 cannabinoid-based nausea treatment. It is a pure synthetic isomer of tetrahydrocannabinol (THC), which allows for good dosage control. Dronabinol is given orally, so it is most suitable to treat nausea rather than vomiting. Typically, in cases of severe vomiting, inhaling cannabis via an electronic temperature-controlled vaporizer is favorable, as it removes the risk of losing the drug alongside the food when throwing up. Also, inhaled cannabis is resorbed quicker into the bloodstream. So it will be able to relieve nausea quicker. If vomiting isn't a problem, then dronabinol would be a favorable option from a medical point of view. The dosage is more controlled, and the side effects are milder than smoked cannabis. Dronabinol comes in sublingual drops (2.5%), capsules (Marinol, 2.5mg/5mg/10mg) or oral solutions (Syndros). Besides nausea, dronabinol has been successfully used to offset the loss of appetite (anorexia) in people with AIDS (Acquired Immune Deficiency Syndrome) who suffer from weight loss.
Risks of cannabis
All of this sounds very good, but there are some situations where, even with severe nausea, consuming cannabis or cannabinoid-based medicine is not a good idea. For example, during pregnancy, nausea affects between 50–75% of women, 0.5–2% suffer from the more extreme form of nausea and vomiting called "hyperemesis gravidarum." However, consuming cannabis in those situations is a mistake, as it can have quite substantial neuro-developmental consequences for the unborn child. Another example would be COVID-19, which often leads to nausea and vomiting. However, self-medicating with cannabis would be a mistake, as it can interfere with common medications given to infected patients and at the same time hinder the immune system's antiviral response. Lastly, overuse of cannabis can lead to cannabis hyperemesis syndrome, which, as the name "hyperemesis" suggests, causes violent, uncontrollable vomiting itself.
- Sharkey, Keith A, and John W Wiley. “The Role of the Endocannabinoid System in the Brain-Gut Axis.” Gastroenterology vol. 151,2 (2016): 252-66. doi:10.1053/j.gastro.2016.04.015 https://pubmed.ncbi.nlm.nih.gov/27133395/
- Camilleri, M. “Cannabinoids and gastrointestinal motility: Pharmacology, clinical effects, and potential therapeutics in humans.” Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society vol. 30,9 (2018): e13370. doi:10.1111/nmo.13370 https://pubmed.ncbi.nlm.nih.gov/29745439/
- Goyal, Hemant et al. “Role of cannabis in digestive disorders.” European journal of gastroenterology & hepatology vol. 29,2 (2017): 135-143. doi:10.1097/MEG.0000000000000779 https://pubmed.ncbi.nlm.nih.gov/27792038/
- Lacy, Brian E et al. “Chronic nausea and vomiting: evaluation and treatment.” The American journal of gastroenterology vol. 113,5 (2018): 647-659. doi:10.1038/s41395-018-0039-2 https://pubmed.ncbi.nlm.nih.gov/29545633/
- Venkatesan, Thangam et al. “Role of chronic cannabis use: Cyclic vomiting syndrome vs cannabinoid hyperemesis syndrome.” Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society vol. 31 Suppl 2,Suppl 2 (2019): e13606. doi:10.1111/nmo.13606 https://pubmed.ncbi.nlm.nih.gov/31241817/
- Gotfried, Jonathan et al. “Role of Cannabis and Its Derivatives in Gastrointestinal and Hepatic Disease.” Gastroenterology vol. 159,1 (2020): 62-80. doi:10.1053/j.gastro.2020.03.087 https://pubmed.ncbi.nlm.nih.gov/32333910/
- May, Megan Brafford, and Ashley E Glode. “Dronabinol for chemotherapy-induced nausea and vomiting unresponsive to antiemetics.” Cancer management and research vol. 8 49-55. 12 May. 2016, doi:10.2147/CMAR.S81425 https://pubmed.ncbi.nlm.nih.gov/27274310/r
- “Dronabinol.” LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, National Institute of Diabetes and Digestive and Kidney Diseases, 15 January 2018. https://pubmed.ncbi.nlm.nih.gov/31644137/
- Taylor, Bryce N., et al. “Cannaboinoid Antiemetic Therapy.” StatPearls, StatPearls Publishing, 25 August 2021. https://pubmed.ncbi.nlm.nih.gov/30571051/