Patient question · asked by Anonymous reader · September 17, 2026
Does cannabis help with nausea during chemotherapy?
I am starting chemotherapy next month and I am already nauseous just thinking about it. Does cannabis actually help with that, or is it wishful thinking?
Patient question: I am starting chemotherapy next month and I am already nauseous just thinking about it. Does cannabis actually help with that, or is it wishful thinking? For nausea that persists despite standard anti-sickness medicine, there is real evidence it helps. In a randomised trial, adding a THC:CBD capsule to the usual regimen raised.
The short answer
Dr. Caplan & CED Research Response
For nausea that persists despite standard anti-sickness medicine, there is real evidence it helps. In a randomised trial, adding a THC:CBD capsule to the usual regimen raised the proportion of people who got through five days with no vomiting and no rescue medication from 8% to 24%. That is a meaningful improvement, though it still leaves most people needing more.
A closer lookWhy the answer is what it is
The important detail is that this was tested as an addition to guideline-standard antiemetics, not as a replacement for them. Nearly everyone in the trial was also taking a corticosteroid and a 5-HT3 antagonist, and most an NK-1 antagonist as well. The cannabis was doing work that those medicines had not managed on their own.
The side effects were not trivial: sedation in 18% versus 7% on placebo, dizziness in 10% versus none, and transient anxiety in 4% versus 1%. No serious adverse events were attributed to it. For someone already exhausted by chemotherapy, added sedation is worth weighing rather than waving away.
This is a conversation to have with your oncology team before your first cycle, partly because timing matters - in the trial, dosing started the day before chemotherapy.
The evidence
The study behind this answer
Verified on PubMed Randomized controlled trial
Oral Cannabis Extract for Chemotherapy-Induced Nausea and Vomiting: A Randomized, Placebo-Controlled Phase II/III Trial
PubMed 39151115
Read the abstract as published
PURPOSE: The aim of this randomized, placebo-controlled, two-stage, phase II/III trial was to determine the efficacy of an oral cannabis extract in adults with refractory nausea and/or vomiting during moderately or highly emetogenic, intravenous chemotherapy despite guideline-consistent antiemetic prophylaxis. Here, we report results of the prespecified combined analysis including the initial phase II and subsequent phase III components.
PATIENTS AND METHODS: Study treatment consisted of oral capsules containing either tetrahydrocannabinol 2.5 mg plus cannabidiol 2.5 mg capsules (THC:CBD) or matching placebo, taken three times a day from days -1 to 5, in addition to guideline-consistent antiemetics. The primary measure of effect was the difference in the proportions of participants with no vomiting or retching and no use of rescue medications (a complete response) during hours 0-120 after the first cycle of chemotherapy on study (cycle A).
RESULTS: We recruited 147 evaluable of a planned 250 participants from 2016 to 2022. Background antiemetic prophylaxis included a corticosteroid and 5-hydroxytryptamine antagonist in 97%, a neurokinin-1 antagonist in 80%, and olanzapine in 10%. THC:CBD compared with placebo improved the complete response rate from 8% to 24% (absolute difference 16%, 95% CI, 4 to 28, P = .01), with similar effects for absence of significant nausea, use of rescue medications, daily vomits, and the nausea scale on the Functional Living Index-Emesis quality-of-life questionnaire. More frequent bothersome adverse events of special interest included sedation (18% v 7%), dizziness (10% v 0%), and transient anxiety (4% v 1%). There were no serious adverse events attributed to THC:CBD.
CONCLUSION: THC:CBD is an effective adjunct for chemotherapy-induced nausea and vomiting despite standard antiemetic prophylaxis, but was associated with additional adverse events. Drug availability, cultural attitudes, legal status, and preferences may affect implementation. Future analyses will evaluate the cost-effectiveness of THC:CBD.
Abstract text as indexed by PubMed for this identifier.
In practice
What this study does and does not change
This is one of the clearer signals we have. It was an add-on to good standard care, not a replacement for it, and the benefit came with real side effects worth discussing before starting.
A physician's read of the cited study, as it appears on that study's page.
More on Cancer More on Nausea More on Vomiting
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Reviewed by Dr. Caplan on September 17, 2026.
This answer is general education. It is not medical advice and does not create a doctor-patient relationship. For care specific to you, book a consultation. In an emergency, call 911.
