A systematic review of systematic reviews found moderate evidence that cannabinoids reduce chemotherapy nausea, but also moderate evidence that they cause more side effects and dropouts than both placebo and conventional antiemetics.
Read this if you are undergoing chemotherapy and considering cannabinoids for nausea management.
Cannabinoids were effective for chemo nausea but had higher dropout rates than both placebo and conventional antiemetics.
What the researchers found
This meta-review examined six systematic reviews of randomized controlled trials comparing cannabinoids (dronabinol, levonantradol, nabilone, and nabiximols) with placebo or conventional antiemetics for chemotherapy-induced nausea and vomiting (CINV).
The evidence showed moderate quality support for cannabinoid efficacy against both placebo and conventional antiemetics. However, there was equally moderate quality evidence that cannabinoids were less tolerated and less safe than both placebo and conventional antiemetics, with higher dropout rates due to adverse events.
Critically, no studies compared cannabinoids with newer neurokinin-1 receptor antagonists, which are now standard in many CINV regimens. Only one RCT of whole plant extract was included.
The authors concluded that with safe and effective modern antiemetics available, cannabinoids should not be first- or second-line therapy for CINV. Some guidelines recommended them as third-line treatment for breakthrough nausea when standard treatments fail.
Why it matters
This review provides the clearest picture of where cannabinoids fit in CINV management: they work, but they are not as well tolerated as modern alternatives. This evidence-based positioning as third-line therapy helps clinicians make informed decisions rather than either dismissing cannabinoids entirely or promoting them as first-choice treatments.
The numbers in context
Six systematic reviews analyzed. Cannabinoids studied: dronabinol, levonantradol, nabilone, nabiximols. Moderate quality evidence for efficacy against placebo and conventional antiemetics. Moderate quality evidence for worse tolerability and safety. One RCT of whole plant extract. No comparisons with neurokinin-1 antagonists.
How the study worked
Systematic review of systematic reviews. Comprehensive search of MEDLINE, DARE, and Cochrane libraries through November 2015 for systematic reviews of RCTs comparing cannabinoids with placebo or conventional antiemetics for CINV. Methodological quality was assessed using AMSTAR.
What this study cannot tell us
The systematic reviews included studied pharmaceutical cannabinoids, not herbal cannabis. Most original trials predated modern antiemetic regimens, so the comparators were older drugs. No comparisons with current standard-of-care antiemetics (neurokinin-1 antagonists). The review was published in German, potentially limiting its reach.
How to read the evidence
Strong evidence from a systematic review of systematic reviews, the highest level of evidence synthesis, though limited by the quality of underlying trials.
When this study was published
Published in 2016. Anti-nausea treatment options have continued to expand, but the basic positioning of cannabinoids as third-line therapy has remained.
The bigger picture
The chemotherapy nausea indication was one of the first medical uses of cannabinoids to gain regulatory approval. This review shows that while the efficacy evidence remains solid, the tolerability disadvantage relative to modern antiemetics has shifted cannabinoids from a primary treatment to a backup option for resistant cases.
Questions still open
- How would cannabinoids compare with modern neurokinin-1 receptor antagonists in head-to-head trials? Would low-dose cannabinoid combinations with standard antiemetics improve outcomes while reducing cannabinoid side effects? Is there a role for CBD-only formulations that might have fewer psychoactive side effects?
Common questions
Are cannabinoids good for chemotherapy nausea?
Why not use cannabis first for chemo nausea?
Read the original research
Efficacy, tolerability, and safety of cannabinoids for chemotherapy-induced nausea and vomiting--a systematic review of systematic reviews.
Schmerz (Berlin, Germany), 30(1), 14-24
Citation
Tafelski, S; Häuser, W; Schäfer, M. (2016). Efficacy, tolerability, and safety of cannabinoids for chemotherapy-induced nausea and vomiting--a systematic review of systematic reviews.. Schmerz (Berlin, Germany), 30(1), 14-24. https://doi.org/10.1007/s00482-015-0092-3
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