For many cancer patients, chemotherapy is a lifesaving treatment. That said, the myriad of side effects connected to chemo can significantly affect quality of life. Nausea and vomiting are by far some of the most common side effects of chemotherapy, affecting 70-80% of patients. While both prescription and over-the-counter antiemetics are widely available, they don’t always work for everyone. They can also cause side effects of their own. Here’s where cannabis comes in. Used medicinally for several centuries for a wide array of conditions, there’s solid evidence to support its efficacy as a natural substance that provides significant relief from nausea and vomiting. Both THC and CBD have been explored for their effects on chemotherapy-induced nausea and vomiting (CINV), but which one is better? That’s exactly what you’ll learn in this article. If you or someone you love is interested in using cannabis to ease CINV, keep reading for a deep dive into cannabis science, where we’ll explore how each cannabinoid supports nausea and vomiting, look at different studies on their benefits, uncover if CBD or THC is better, or if the best approach might be using them together.
What is Chemotherapy-Induced Nausea and Vomiting (CINV)?
Chemotherapy-induced nausea and vomiting (CINV) is one of the most common side effects of cancer treatment, affecting 70-80% of patients undergoing chemotherapy. Not all cancer patients experience CINV the same though, and symptoms can be worse for some more than others. Despite the severity of symptoms, there are three main “types,” including: - Acute: Acute CINV occurs within the first 24 hours after receiving treatment and is typically triggered by the body’s initial response to chemotherapy drugs. - Delayed: Delayed CINV usually happens more than 24 hours after treatment and typically lasts 2-3 days, although it can last up to 5 days depending on the type and dose of drugs used. - Anticipatory: Anticipatory CINV is a psychological response triggered by past experiences with nausea and vomiting that can happen before chemotherapy treatment. CINV is different from the occasional nausea people experience from time to time, with research showing it can have a huge impact on a patient's quality of life. It doesn’t just cause physical discomfort. CINV can lead to nutritional deficiencies, dehydration, and loss of electrolytes when the patient needs all the strength they can to get well. The fear of getting nauseous or vomiting after eating makes some patients skip meals entirely, leading to malnutrition, which can delay or cause complications in recovery. CINV can also lead to anxiety, depression, stress, and social isolation. For some, CINV can be so bad that they skip chemo treatments or stop going altogether. While antiemetic drugs are generally well-tolerated and can provide relief from nausea and vomiting, they don’t work for everyone. There’s research to support that despite their effectiveness, 30-60% of chemo patients still experience acute or delayed nausea after treatment. For some, the side effects of antiemetic drugs, including headache, dizziness, dry mouth, fatigue, constipation, and diarrhea, can feel just as CINV.
Research on Cannabis for CINV
Ineffective options for nausea and vomiting associated with chemotherapy caused oncologists to explore the antiemetic properties of cannabis in the 1970s. The first was a 1975 study based on anecdotal reports suggesting that “smoking marihuana decreases the nausea and vomiting associated with cancer chemotherapeutic agents.” An antiemetic effect was observed in 14 of 20 participants, with researchers noting that none of them vomited while “high.” They concluded by saying, “Oral tetrahydrocannabinol has antiemetic properties and is significantly better than a placebo in reducing vomiting caused by chemotherapeutic agents.” By 1985, the FDA had approved dronabinol, a synthetic version of THC, which was available under the name Marinol for nausea and vomiting caused by chemotherapy. Since then, research on how cannabis has expanded significantly, including its efficacy in treating nausea and vomiting. According to the National Cancer Institute, 20-40% of people treated for cancer currently use cannabis to manage side effects like nausea, pain, anxiety, and stress. Both THC and CBD are thought to relieve nausea and vomiting, but which works better? Before exploring the role each cannabinoid plays in CINV, it’s important to understand why cannabis relieves nausea and vomiting in the first place.
How THC and CBD Support Nausea and Vomiting
The way nausea and vomiting occur is connected to complex interactions between the brain and gut. According to research, the body’s endocannabinoid system (ECS) helps regulate this process. CB1 receptors are abundant throughout the brain and gut, including all areas involved in nausea and vomiting. Activating CB1 receptors reduces serotonin release in the gut, which is what ultimately helps quiet the signals that trigger nausea and vomiting. Here’s a simple explanation of how it works. Chemotherapy, radiation, and various toxins can trigger the release of serotonin from enterochromaffin cells in the gut. The serotonin then activates vagus nerves, which send signals to different brain areas responsible for regulating nausea and vomiting. The amygdala, insular cortex, and anterior cingulate cortex (which all process emotions, stress, and fear) are responsible for nausea, while vomiting involves the dorsal vagal complex. There’s a large body of evidence that suggests cannabinoids may be particularly beneficial for treating the often difficult-to-control symptoms of nausea and anticipatory nausea in chemotherapy patients. It’s the way CBD and THC influence the ECS that’s largely responsible for the effects of cannabis on CINV. But understanding their roles starts with examining how they interact with the body, which we’ll explore next.
The Role of THC in CINV
As the most well-known and widely-studied cannabinoid, THC is primarily responsible for several of the effects of cannabis, including psychoactivity, pain-relieving potential, and more. Its therapeutic benefits are largely connected to its strong binding affinity to CB1 receptors, including its efficacy in reducing nausea and vomiting. When THC binds to CB1 receptors, it inhibits serotonin release in the gut, which disturbs signals sent to the brain that cause nausea and vomiting. The result? Significant relief from the often extremely uncomfortable, overwhelming nausea and vomiting that can follow chemotherapy.
What Research Says
Small studies that started in the 1970s to recent clinical trials show overwhelming evidence of the anti-anemic effects of THC. In a 1983 review exploring the research problems and issues of THC for cancer chemotherapy, scientists stated, “We believe that THC does have antiemetic efficacy, but the lack of controlled research does not allow precise knowledge of its true effectiveness and toxicity.” They noted that an increase in well-controlled trials was needed to determine more. Since the early ‘80s, several pre-clinical and clinical trials have explored the efficacy of THC for nausea and vomiting. Nabilone and dronabinol are the two FDA-approved cannabinoid medications for nausea and vomiting caused by chemotherapy, both of which are synthetic analogs of THC that have been extensively studied. A 2019 review cited several research studies that support the efficacy of THC in reducing nausea and vomiting, particularly during chemotherapy, with a specific focus on CBD. While there is overwhelming evidence that THC is effective for CINV, it might not be the best choice for everyone. Its psychoactive effects aren’t something all cancer patients want to experience, despite the cannabinoid’s effectiveness in reducing nausea and vomiting. If so, they may find CBD is a better option, as the non-psychoactive cannabinoid has gained some serious attention for its efficacy in supporting patients with CINV.
CBD for CINV
CBD works a bit differently than THC for nausea and vomiting, having more of an indirect relationship with the ECS to produce its antiemetic effects. While CBD also influences serotonin levels, it doesn’t bind to CB1 receptors to directly increase serotonin. However, research does show it directly influences 5HT1A serotonin receptors, which help regulate the release of serotonin to reduce nausea and vomiting. With its well-researched anti-inflammatory properties, CBD may also help reduce inflammation in the gut, something common in chemotherapy.
What Research Says
While there is supporting evidence that CBD can work effectively to reduce nausea and vomiting, its acidic precursor CBDA is said to work even better. In a 2021 review, researchers examined current evidence of the effectiveness of both CBD and CBDA for managing nausea and vomiting. Not only did they find CBD to be effective, but they also discovered that CBDA was more powerful, highlighting that CBDA was 1,000 times more potent than CBD in reducing acute nausea. The effects of both were mediated by their influence on 5HT1A receptors. CBD’s non-intoxicating nature ensures that chemotherapy patients can experience relief without the high associated with THC. Whether used alone or with THC, CBD products hold powerful promise for individuals undergoing treatment who experience. When it comes to managing chemotherapy-induced nausea and vomiting (CINV), both THC and CBD offer unique benefits. But is one better than the other? The answer isn’t straightforward, as these cannabinoids are said to work best together.
Combining CBD and THC for Chemo-Induced Nausea and Vomiting
For patients interested in the most comprehensive relief from CINV, combining CBD and THC is likely the best bet. A 2023 study examining the efficacy of oral THC/CBD extract for cancer patients who experience CINV during treatment found “a significant increase in the proportion of patients achieving a complete response in chemotherapy-induced nausea and vomiting” that was well-tolerated. THC’s direct activation of CB1 receptors that reduces nausea and vomiting and stimulates appetite, combined with CBD’s influence on serotonin receptors and anti-inflammatory benefits, creates a powerfully balanced synergy. The presence of CBD boosts the antiemetic properties of THC while minimizing its psychoactive effects. Ultimately, this means cannabis products containing a 1:1 THC/CBD ratio could be particularly effective for CINV, offering enhanced relief without overwhelming intoxication which could be more tolerable for some consumers. It’s important to remember that every patient is different, and what works for one may not work for another. Factors such as a patient’s tolerance to THC, sensitivity to psychoactive effects, and personal preferences play a critical role in determining the best approach. Some may prefer THC’s strong antiemetic effects, while others might lean toward CBD for its non-psychoactive properties and gentler side effect profile. Combination therapy can often strike the right balance, but starting low and going slow is key to finding your personal sweet spot.
What are the Best Cannabis Products for Cancer Patients with CINV?
Choosing the best cannabis product for CINV all comes down to your personal needs and desired outcomes. There are several cannabis products on the market, all consumed in different ways, each with unique benefits. For patients looking for the fastest relief from nausea or vomiting after treatment, recent research shows smoking cannabis flower provides the most rapid effects, even more so than vaping cannabis extracts. That being said, smoking isn’t always ideal for cancer patients, especially those with respiratory issues. And while edibles are a popular alternative, some cancer patients find it difficult to eat or swallow anything after chemo. This is what makes RSO syringes a popular option for countless cancer patients. This highly concentrated, full-spectrum extract can be applied under the tongue, where it’s absorbed by mucous membranes before making its way to the bloodstream. RSO has been used for years to manage cancer symptoms and support overall wellness. Its rich cannabinoid and terpene profile enhances the entourage effect, meaning it’s likely more effective for CINV than isolated cannabinoid products. Choosing the right cannabis product to support chemo nausea and vomiting is imperative for the best possible relief. RSO and other full-spectrum products offer the benefits of THC, CBD, and other cannabinoids and terpenes working together, while isolates contain just one compound. Full-spectrum products are widely preferred for medical use because of their enhanced therapeutic potential.
Last Thoughts
For cancer patients interested in using cannabis to manage chemotherapy-induced nausea and vomiting (CINV), both THC and CBD contain powerful effects, each working differently in the body and offering unique benefits. THC has been used for its powerful antiemetic effects for decades, directly targeting CB1 receptors to reduce nausea and stimulate appetite. CBD offers a non-intoxicating option by influencing serotonin and reducing gut inflammation. It’s a combination of the two cannabinoids, however, such as a balanced 1:1 THC/CBD ratio, that’s said to provide the most effective relief. Finding the right cannabis product for CINV all depends on the patient’s individual needs, preferences, and tolerances. If you’re exploring cannabis as an option to help manage CINV during cancer treatment, it’s recommended to speak with your doctor beforehand. By using cannabis products that best support their unique needs, patients can find effective relief, experience more comfort during treatment, and significantly improve their quality of life during this challenging time.