Cochrane Review: Cannabinoids May Help Chemotherapy Nausea but Have Significant Side Effects | Research

The takeaway

A Cochrane review of 23 trials found cannabinoids were better than placebo for chemotherapy-induced nausea and vomiting, roughly equal to older anti-emetics, but caused more side effects including dizziness, dysphoria, and feeling high.

Read this if you are considering cannabinoids for chemotherapy-related nausea or want the most rigorous evidence summary available.

5.7x more likely to have no vomiting with cannabinoids vs. placebo

What the researchers found

This Cochrane systematic review analyzed 23 randomized controlled trials of cannabis-based medications for chemotherapy-induced nausea and vomiting, all conducted between 1975 and 1991.

Compared to placebo, cannabinoids significantly increased complete absence of vomiting (RR 5.7) and complete absence of nausea and vomiting (RR 2.9). Patients preferred cannabinoids over placebo (RR 4.8).

Compared to the older anti-emetic prochlorperazine, cannabinoids were not significantly different for nausea or vomiting control, but caused more dizziness (RR 2.4), euphoria (RR 18), feeling high (RR 6.2), and sedation (RR 1.4). Despite more side effects, patients preferred cannabinoids over prochlorperazine (RR 3.3).

No trials compared cannabinoids with modern anti-emetics like ondansetron.

Why it matters

This is the most rigorous review of cannabinoids for chemotherapy nausea, but it highlights a major limitation: all trials used old chemotherapy and anti-emetic regimens. How cannabinoids compare to modern treatments remains unknown.

The numbers in context

23 RCTs; vs. placebo: RR 5.7 for no vomiting, RR 2.9 for no nausea/vomiting; vs. prochlorperazine: similar efficacy but RR 2.4 for dizziness, RR 18 for euphoria, RR 6.2 for feeling high; patient preference: RR 3.3 vs. prochlorperazine

How the study worked

Cochrane systematic review and meta-analysis of 23 RCTs. Searched CENTRAL, MEDLINE, EMBASE, PsycINFO, and LILACS through January 2015. Random effects meta-analysis with risk ratios.

What this study cannot tell us

All trials from 1975-1991. No comparison with ondansetron or other modern anti-emetics. Most trials at risk of bias. Low to moderate quality evidence. Do not reflect current chemotherapy regimens.

How to read the evidence

Cochrane systematic review (gold standard), but underlying evidence was graded as low quality for most outcomes due to trial age, bias risk, and outdated comparators.

When this study was published

Published in 2015 reviewing trials from 1975-1991. The absence of trials comparing cannabinoids to modern anti-emetics remains a significant evidence gap.

The bigger picture

Despite being the gold-standard review type, this Cochrane review was limited by the age of the available evidence. Modern chemotherapy causes different patterns of nausea, and modern anti-emetics are much more effective than the comparators used in these old trials.

Questions still open

How do cannabinoids compare to ondansetron and other modern 5-HT3 antagonists? Would newer cannabinoid formulations (like nabiximols) perform differently? Is there a role for cannabinoids as add-on therapy when modern anti-emetics fail?

Common questions

Do cannabinoids work for chemotherapy nausea?

Yes, they were significantly better than placebo in this review. However, all 23 trials used old chemotherapy and old comparator anti-emetics. How cannabinoids compare to modern treatments like ondansetron is unknown.

Why did patients prefer cannabinoids despite more side effects?

Despite causing more dizziness, euphoria, and sedation, patients consistently preferred cannabinoids over both placebo and older anti-emetics. This may reflect that the psychoactive effects were considered tolerable or even desirable compared to uncontrolled nausea and vomiting.

Read the original research

Cannabinoids for nausea and vomiting in adults with cancer receiving chemotherapy.

The Cochrane database of systematic reviews, 2015(11), CD009464

View on PubMed ↗Publisher’s paper ↗

Citation

Smith, Lesley A; Azariah, Fredric; Lavender, Verna T C; Stoner, Nicola S; Bettiol, Silvana. (2015). Cannabinoids for nausea and vomiting in adults with cancer receiving chemotherapy.. The Cochrane database of systematic reviews, 2015(11), CD009464. https://doi.org/10.1002/14651858.CD009464.pub2