Oral THC/CBD capsules improved chemo nausea when standard anti-nausea drugs failed

What the researchers found

Complete response improved from 14% with placebo to 25% with THC:CBD (RR 1.77, p=0.041). Similar improvements were seen for absence of emesis, use of rescue medications, and quality-of-life scores. However, 31% experienced moderate or severe cannabinoid-related side effects like sedation and dizziness.

Why it matters

This is one of the first rigorous trials of standardized oral THC:CBD for refractory chemotherapy nausea, a significant unmet need since many patients fail standard antiemetics.

The numbers in context

81 randomized, 72 completed efficacy analysis. Complete response: 25% THC:CBD vs 14% placebo (RR 1.77, 90% CI 1.12-2.79). 31% had moderate-severe cannabinoid side effects. 83% preferred cannabis. Median age 55, 78% female.

How the study worked

Phase II, multicentre, double-blind, placebo-controlled crossover trial. Patients who experienced CINV despite guideline-consistent antiemetics received self-titrated THC 2.5mg/CBD 2.5mg capsules (1-4 capsules, three times daily, days -1 to 5) or matching placebo across two chemotherapy cycles.

What this study cannot tell us

Small phase II sample. Self-titrated dosing introduces variability. The 31% rate of moderate-severe side effects (sedation, dizziness, disorientation) is significant and may limit practical use.

How to read the evidence

Strong: randomized, double-blind, placebo-controlled crossover design, though limited by phase II sample size.

When this study was published

Published in 2020 in Annals of Oncology.

The bigger picture

The strong patient preference (83%) for cannabis despite notable side effects suggests patients found the nausea relief worth the trade-off, supporting further investigation in the planned phase III expansion.

Questions still open

• Will the phase III trial with 170 additional participants confirm these findings? Can dosing optimization reduce side effects while maintaining efficacy? How does THC:CBD compare to other rescue antiemetics?

Common questions

Read the original research

Oral THC:CBD cannabis extract for refractory chemotherapy-induced nausea and vomiting: a randomised, placebo-controlled, phase II crossover trial.

Annals of oncology : official journal of the European Society for Medical Oncology, 31(11), 1553-1560

Citation

Grimison, P; Mersiades, A; Kirby, A; Lintzeris, N; Morton, R; Haber, P; Olver, I; Walsh, A; McGregor, I; Cheung, Y; Tognela, A; Hahn, C; Briscoe, K; Aghmesheh, M; Fox, P; Abdi, E; Clarke, S; Della-Fiorentina, S; Shannon, J; Gedye, C; Begbie, S; Simes, J; Stockler, M. (2020). Oral THC:CBD cannabis extract for refractory chemotherapy-induced nausea and vomiting: a randomised, placebo-controlled, phase II crossover trial.. Annals of oncology : official journal of the European Society for Medical Oncology, 31(11), 1553-1560. https://doi.org/10.1016/j.annonc.2020.07.020

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