How Well Do Cannabinoids Control Chemotherapy Nausea? A Systematic Review of 30 Trials

This was a quantitative systematic review with comprehensive searching across Medline, Embase, the Cochrane Library, and bibliographies in any language through August 2000. Thirty randomized comparisons with dichotomous efficacy and harm data were included, covering 1,366 patients. All tested oral nabilone, oral dronabinol, or intramuscular levonantradol against placebo or conventional antiemetics. No study used smoked cannabis.

This was one of the most rigorous early systematic reviews of cannabinoids for chemotherapy-induced nausea and vomiting. By quantifying both benefits and harms with numbers needed to treat, it provided clinicians with practical data for decision-making. The finding that patients strongly preferred cannabinoids despite side effects suggested the anti-nausea benefit was highly valued by people undergoing chemotherapy.

This review helped establish the evidence base for the continued use of dronabinol and nabilone as antiemetics, which remain approved for chemotherapy-induced nausea. However, the development of 5-HT3 receptor antagonists (ondansetron and similar drugs) in the 1990s provided alternatives with fewer psychoactive side effects, limiting the role of cannabinoids to patients who do not respond adequately to newer antiemetics.

None of the included trials used smoked cannabis, so results apply only to oral and intramuscular pharmaceutical cannabinoids. The comparator antiemetics were older drugs; no trials compared cannabinoids with newer 5-HT3 antagonists. Follow-up lasted only 24 hours. The trials were conducted primarily in the 1970s-1990s with varying quality standards.