Cannabinoids
Also called: nabilone, dronabinol, THC medicines.
Last reviewed 2026-09-16. How this works.
When to call your team — there is nothing to watch for
Whatever you are taking or thinking of taking, the people treating you can only weigh it if they know about it. That is true when nothing has been written down here, and it is most true then.
These are prescribed medicines. The side effects recorded on this page are the reason a prescriber monitors them, so there is nothing here for a reader to watch for on their own. That is not a statement that nothing can go wrong.
This block is about what to watch for, and it is not all this page holds: what has been recorded about harm is below. Nothing in this block is an all-clear for a question it does not mention.
Chemotherapy-induced nausea and vomiting Grade B
Good human evidence, with a limit worth knowing.
Harm has been recorded in people for this claim. The grade measures how strong the evidence for benefit is; it says nothing about the harm, and the two are read from different parts of this page.
These medicines do work for sickness from chemotherapy, but they were tested against older drugs than the ones used now.
Pooled randomised evidence, against comparators that modern practice has moved past.
The harm
Both reviews record side effects as a real limit. More people withdrew from the cannabinoid arms because of an adverse effect, and the older review concluded that potentially serious adverse effects are likely to limit widespread use.21
The claim
The claim is that cannabinoid medicines control the nausea and vomiting that chemotherapy causes. Unlike most of this chapter, the claim is largely correct.
What it does
Cannabinoid receptors are present in the parts of the brain that generate nausea and vomiting, and the licensed medicines act there. This is a symptom effect and makes no claim on the tumour.
The evidence
A systematic review pooled thirty randomised comparisons across 1,366 patients. Cannabinoids were more effective than the anti-sickness drugs of the time for complete control of nausea and of vomiting, and in crossover trials people preferred them for future cycles.1
A Cochrane review found that compared with placebo, people were more likely to report complete absence of vomiting and complete absence of nausea and vomiting, though it graded the quality of evidence low for most outcomes.2
Here is the catch, and both reviews state it themselves. The trials were run against anti-sickness drugs that modern practice has largely moved past, and the Cochrane review records that they do not reflect current chemotherapy and antiemetic regimens. A drug that beat the standard of 1995 has not been shown to beat the standard of today.12
The oldest review also notes that all the medicines tested were taken by mouth or injected. No cannabis was smoked in any of them.1
The studies this rests on
-
Pooled randomised comparisons of cannabinoids for chemotherapy-induced nausea and vomiting1
A meta-analysis, summarising randomised trials, measured what patients reported, 1366 participants.
more effective than the comparator anti-sickness drugs for complete control of nausea and of vomiting.
relative risk 1.38, interval 1.18 to 1.62. complete control of nausea, number needed to treat 6; vomiting 1.28, interval 1.08 to 1.51, number needed to treat 8
What is absent
No trial in this record compared a cannabinoid medicine against the anti-sickness drugs used today. Every comparison was against an older standard.
Scope: against current anti-sickness treatment.
Established by published review, Cochrane Database of Systematic Reviews, CD009464, checked 2026-09-16. Result: the review records that the trials do not reflect current chemotherapy and antiemetic treatment regimens.21
What to ask
Is a cannabinoid medicine something you would consider if the anti-sickness drugs I am on are not working?
The dish-to-person gap
The register records no human pharmacokinetic measurement for the licensed cannabinoid medicines. This entry is about a symptom benefit rather than a concentration reaching a tumour.
Interactions
The register holds no measured interaction between licensed cannabinoid medicines and a cancer treatment class. The cannabis entry carries a separate finding about immunotherapy that is worth reading alongside this one.
Nobody having looked is not the same as nothing being there. That is what this line says and all it says.
The whole interaction list, and how to turn it into a pharmacy review request.
Find a trial instead
These are licensed medicines available on prescription rather than compounds to seek a trial for.
References
Cannabinoids for control of chemotherapy induced nausea and vomiting: quantitative systematic review. BMJ, 2001.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 19 note 1.
Cannabis-based medicines for nausea and vomiting in adults with cancer receiving chemotherapy. Cochrane Database of Systematic Reviews, CD009464.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 19 note 2.