Nausea and Vomiting

Relatively high THC cannabis is recommended for treating nausea over using CBD-only products, according to the Australian Department of Health (1). It is important to note that in rare cases, prolonged use of cannabis may cause cannabinoid hyperemesis syndrome, a syndrome that causes cyclical vomiting until use is stopped, and may need ER treatment for secondary dehydration or other complications (10). 

If smoking to manage nausea, it is important to pick high THC cannabis plant flower, because this chemical compound directly affects the dorsal vagus nerve, which controls nausea and vomiting responses in humans (5). Another ideal option is using a vaporizer or vape pen if the patient is worried about smoke being harmful (3). Smoking or vaping may carry additional health risks.

Because orally taking cannabis takes an hour to two hours to start taking effect and lasts longer in the body, many patients prefer to inhale cannabis for immediate relief and quicker offset. When taking medical marijuana orally, it can be more difficult to adjust exact dosages, but it can deliver cannabinoids (chemical compounds found in marijuana) without the need for smoking or vaping (3).

High THC doses of cannabis are recommended for the treatment of cancer-related nausea due to chemotherapy (1). Research shows that cannabinoids, including prescription-based ones, are more effective than traditional medications for nausea at reducing vomiting and nausea for patients undergoing cancer chemotherapy. If you are receiving emetogenic chemotherapy treatment, a type of chemotherapy that causes larger amounts of vomiting and nausea, cannabis is not more effective than anti-nausea medications for symptom relief (2).

A 2016 review discusses the research of cannabis and nausea, noting that activation of the endocannabinoid system can increase the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) when a patient is experiencing motion sickness or after receiving certain types of anesthesia. Unfortunately, this evidence has been shown in animal studies but has yet to be clinically researched in humans (11).

Additionally, there is promising evidence that cannabis may help the 25- 59% of chemotherapy patients who develop anticipatory nausea. Anticipatory nausea happens when a patient’s acute nausea from chemotherapy is not properly treated and then the patient has a conditioned response of being nauseated when returning to the clinic for more treatment sessions.  Researchers believe that, unlike traditional antiemetics, cannabis has the ability to help this group of patients (11). 

Many patients with human immunodeficiency virus (HIV) take medications to suppress the effects of the virus on their body, but then suffer side effects of these medications. These antiviral medications, called protease inhibitors, are highly effective at helping patients from getting sick, but cause nausea and vomiting that is similar to chemotherapy-induced nausea (3).

In HIV patients, studies support medical marijuana use and dronabinol to treat nausea and cachexia or wasting syndrome, which causes severe weight loss. When patients were given larger doses of cannabis or dronabinol, their weight increased between 3.5-3.9% percent; this is something that traditional medications for nausea have not been shown to improve (9).  

More research needs to be done in this area as many of these studies are short and contain a small number of participants or some research bias when it comes to dronabinol (12). 

Check out our informative page on HIV.