An indication with important qualifiers
Dronabinol and nabilone are regulated medicines with defined indications that include chemotherapy-related nausea and vomiting in particular circumstances. That is different from evidence for dispensary products, CBD alone, or cannabis as cancer treatment.
Many cannabinoid antiemetic trials predate current multi-drug prevention regimens. Older comparisons can therefore answer a different question from the one faced in modern oncology care.
What current guidance says
The 2024 ASCO guideline found the strongest supportive-care evidence in refractory chemotherapy-induced nausea and vomiting. It advises against replacing cancer-directed treatment with cannabis or cannabinoids and does not support using them to improve cancer control outside a clinical trial.
Adverse effects, interactions, formulation, and concurrent cancer medicines matter. Evidence for one prescription product does not validate every cannabinoid product.
Clinical context comes first
Persistent vomiting during treatment can require prompt oncology assessment. Decisions about prescription cannabinoids belong within the antiemetic plan developed by the treating team, rather than being added without medication review.