Ask Dr. Leigh: how can cannabis ease nausea from chemotherapy?

cannabis chemotherapy

Using cannabis can have a big impact on your physical and mental health—for better and, once in a while, for worse. That’s why it’s important to consult a healthcare provider before experimenting.

Here at GreenState, cannabis clinician Dr. Leigh Vinocur is here to answer your questions on healthy living with cannabis.

RELATED: Ask Dr. Leigh: can cannabis help ease MS?

Editor’s Note: The answer to this question is meant to supplement, not replace, advice, diagnoses, and treatment from a healthcare provider.  Always consult a medical professional when using cannabis for medicinal purposes, and do not disregard the advice of your healthcare provider because of anything you may read in this article. 

Q) How does medical cannabis help with nausea and vomiting from chemotherapy? 

Chemotherapy-induced nausea and vomiting (CINV) is kind of a defense mechanism. The body interprets the chemo as a noxious, almost poisonous foreign substance. This causes the body to trigger the vomiting center, which is a part of the brainstem called the medulla oblongata or postrema area that contains the chemoreceptor trigger zone (CTZ). It’s estimated that it can affect 60-80% of cancer patients.  

In fact, we know that chemotherapy can be toxic not only to cancer cells but also to our normal cells. This creates a reaction in our gastrointestinal tract, which releases chemicals and neurotransmitters such as Substance P and serotonin that bind to the receptors in the CTZ, triggering the vomiting reflex

There are a few classifications of the different types of CINV, according to when they occur with respect to the chemo treatments—classifications such as acute within 24 hours of therapy and delayed after 24 hours. Anticipatory CINV is a conditioned response that happens when patients just think of something or experience a smell or taste that is associated with getting chemotherapy. I have had patients report that even just walking into the building where they receive their chemotherapy can trigger it. Therefore, the aim of any anti-emetic (anti-nausea) medication regime involves pre-treatment before going to chemo. 

CINV can cause serious medical complications such as dehydration and electrolyte abnormalities, as well as the severely debilitating nature of nausea, which in turn affects the quality of life during cancer treatment. Additionally, it can affect clinical outcomes. Prolonged nausea and vomiting with cancer treatments that lead to significant weight loss and cachexia (muscle wasting) are a poor prognostic indicator affecting survival.  

We know serotonin is a neurotransmitter that has a role in vomiting and CINV and that the endocannabinoid system (ECS) has a role in nausea and vomiting in humans and many animals. Our internal endocannabinoids interact with both the CB1 receptors and the serotonin receptors in both the vomiting center of the brain and the GI tract

The role of cannabis as an anti-nausea 

Phytocannabinoids from the cannabis plant also exert their anti-emetic (anti-nausea) effect by inhibiting serotonin in the brain and the CB1 receptors in the GI tract, decreasing gastrointestinal motility. For example, CBD can interact with serotonin receptors and prevent the binding of serotonin to stop nausea and vomiting. THC does this as well, and it also interacts with cannabinoid receptors (CB1 and CB2) in that area of the brain and GI tract.  Thus, both plant cannabinoids (CBD and THC) have a role in the treatment of CINV. 

In fact, back in 1985, Marinol, which is a pharmaceutical product that is a synthetic THC molecule, was actually approved by the FDA to treat CINV, weight loss, and cachexia in HIV/AIDS patients. This highlights the ridiculous hypocrisy of the federal government’s classifying natural cannabis as Schedule I, listed as having no accepted medical use and high abuse potential. In 1999, they rescheduled Marinol, a synthetic pharmaceutical THC, to Schedule II due to its lower abuse potential!   

Since FDA approval of synthetic THC, there have been a plethora of clinical trials that look at plant-based cannabis use in CINV. A Google Scholar search brings up over 1200 published peer-reviewed papers on the topic today. And CINV is one of the more universally accepted uses for cannabis in medicine today. Even a generally conservative consumer medical website like WebMD lists controlling nausea and vomiting during chemotherapy as a major benefit of medical cannabis.  And most of the cancer patients that get referred to me by their oncologists are for medical cannabis use to help manage their CINV. 

Agencies such as the National Cancer Institute discuss cannabis use for various cancer symptoms, such as CINV, on their website. They mention its promising areas of future study and use, as well as supporting the need to remove barriers to more clinical trials. The American Cancer Society’s website also discusses various aspects of cannabis use in cancer treatment, highlighting its potential benefits in treating nausea and vomiting induced by chemotherapy. It also touches on the different methods of consuming marijuana and their varying effects. 

In my practice, I do recommend that patients have several different forms of cannabis available to use, such as edibles for their long-lasting effects, tinctures used under your tongue which can start acting a little faster than edibles, and some flower to vape (not smoke) for breakthrough symptoms. Finding combinations that work for you is very personalized like most medical cannabis regimens are. You should work with your doctor to find the right combination of cannabis forms (edible, tincture, flower) and types, such as ratios of different cannabinoids in products (THC-dominant, CBD-dominant, 1:1 ratios THC:CBD) and even sometimes in combination with other approved pharmaceutical anti-emetic meds according to the classification of CINV that you experience.

Could rescheduling shift the narrative?

An extensive review study published by the Cochran review, which is a large research database that reviews many published clinical trials on a specific medical topic, found that patients prefer cannabis for CINV over a placebo in clinical trials. But they still recommend more clinical trials.

Part of the recurring problem we see with clinical trials on Schedule I substances is there are no national standards for the type of cannabis product used in these trials and information on specific dosing of the product that is needed to create clinically reproducible clinical guidelines and recommendations for treatment. Each state has its own standards and products. But until rescheduling occurs, at present, there is enough general data that support the use of cannabinoids in CINV. 

In conclusion, patients considering cannabis or cannabinoid therapy for CINV should consult with their oncologist to discuss potential risks and benefits. If your oncologist agrees with you but does not certify or manage patients on medical cannabis, you can check with your local state medical cannabis agency. They should have a list of physicians that can certify you—and that means not only just approving you for its use. 

The doctor should take the time to review your medical records and explain our endocannabinoid system and how cannabis will interact with your specific medical condition. They should make sure you will not have any drug interactions with other medications you are taking. They should give you specific initial recommendations of the available product types in your state, such as those with differing ratios of cannabinoids (THC-dominant, CBD-dominant, 1:1 ratio THC:CBD) and the different recommended methods of use, such as inhaled (vaping not smoking) edibles and tinctures.

 Additionally, they should give you specific recommendations for your initial dosing, as well as be willing to follow up with you and be available to answer your questions once you start using medical cannabis. While this is a form of personalized medicine, a good cannabis clinician will help guide you every step of the way while you find your ideal medical regimen.