Studies of medical marijuana have shown that it significantly reduces nausea and vomiting. It can be consumed as flowers, concentrates, edibles, and vapes. The time to relieve symptoms varies based on the type of product used and how it is consumed.
Cannabis rapidly reduces nausea by activating CB1 receptor responses in the brain. This suppresses conditioned vomiting and conditioned gaping responses in rats.
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Severe Nausea
Cannabis can provide significant relief for chemotherapy-induced nausea and vomiting (CINV) when other medications are not working. In several trials, crude marijuana or synthetic delta-9-tetrahydrocannabinol is more effective than placebo or the standard antiemetics used with cancer treatments.
Medical marijuana is also known to improve appetite, which can be a problem for patients who are experiencing nausea and are not eating due to their condition. In a small clinical trial, a cannabis extract (nabiximols/Sativex) was found to be more effective than an active comparator levonantradol at increasing appetite in people with CINV and AIDS-related nausea.
While the cannabis product was associated with side effects such as sedation and dizziness, these were considered to be manageable by people who used it. This evidence supports the recommendation that people can use medicinal cannabis for CINV, provided they are informed about the potential adverse effects and do not experience other health problems such as anxiety or psychotic symptoms.
Mild Nausea
There is only limited evidence to support the use of medicinal cannabis to treat nausea and vomiting. However, the broader therapeutic potential of the medicinal plant and the underlying therapeutic principle to not harm means that health professionals should consider supporting patients who wish to use an unapproved treatment option, such as medicinal cannabis, in cases where newer standard approved antiemetics are not providing adequate relief.
The cannabis plant has been used for centuries for a variety of medicinal purposes, including how does weed help nausea. In the 1970s and 1980s, synthetic D9-THC (nabilone) entered clinical practice as an antiemetic in combination with prochlorperazine to control chemotherapy-induced nausea and vomiting.
Medical marijuana is available in pills, tinctures, and liquids for vaporization, as well as in the form of dried leaves or buds or the whole cannabis plant. Various administration methods yield different effects, with inhalation via smoke offering the fastest response and highest level of relief. However, some patients find inhalation uncomfortable and may experience a dry mouth or cough.
Medical marijuana is also used to help people eat more, to control pain caused by HIV/AIDS and other illnesses, to treat glaucoma, and to ease anxiety, depression, and stress. In addition, some research indicates that marijuana lowers the pressure in the eyes associated with glaucoma, but this effect does not last long.
Moderate Nausea
The pharmaceutical cannabis products, dronabinol and nabilone, are used in pill form to treat chemotherapy-induced nausea and vomiting (CINV) and to stimulate appetite in patients with AIDS-defining illnesses. They have been demonstrated to be more effective than placebo and at least as productive as several antiemetics used in conventional clinical trials. However, these medicinal cannabis studies produced low to moderate-quality evidence and compared the cannabis-based medicines with drugs that were historically used or their active comparators.
Medicinal cannabis has been shown to attenuate nausea in animal models. For example, in the conditioned gaping model of anorexia, D9-THC attenuated conditioned retching and conditioned gaping. These findings support anecdotal reports that the endocannabinoid system plays a critical role in controlling both nausea and anorexia.
In a tiny study, smoked cannabis sativa was found to be as effective as the antiemetic prochlorperazine at reducing self-reported nausea and vomiting in cancer patients with CINV. However, some are concerned that smoked marijuana may increase nausea and other side effects in some individuals.
No Nausea
Medical marijuana is effective for treating nausea in some cases, and the FDA has approved several cannabinoid-based prescription drugs that treat cancer-related nausea. However, smoking cannabis has serious health risks and carries a greater risk of respiratory problems than taking an oral medication. Smoking also increases the risk of developing heart and lung disease and has been linked to psychotic disorders.
In a limited number of studies, medicinal cannabis was found to promote appetite in patients with HIV/AIDS-associated anorexia and wasting syndrome. However, some of these trials had poor quality evidence and compared medicinal cannabis with antiemetics that were already available as standard treatments in the 1990s. Other studies reported that smoked cannabis sativa does not enhance appetite in patients with CINV or AIDS-related nausea. One study reported a case of cannabinoid hyperemesis syndrome (CHS), a severe condition that causes cyclic vomiting and is unresponsive to standard antiemetic therapy.
Medicinal cannabis is not an effective treatment for nausea and vomiting in the acute care hospital setting. High-THC medicinal cannabis should only be prescribed after an accepted clinical algorithm has been followed and newer standard-approved medicines have failed or if they are contraindicated. A set of guidance documents has been developed to assist doctors and their patients who choose to access medicinal cannabis under current access schemes. These include an overview addressing the available evidence for medicinal cannabis and documents specific to palliative care, epilepsy, inflammatory bowel diseases, and chemotherapy-induced nausea and vomiting settings.
