• Treating the cancer itself: Not established. The American Society of Clinical Oncology (ASCO) advises against cannabis as cancer treatment outside a clinical trial.

• Chemotherapy nausea and vomiting: Strong. Dronabinol and nabilone are FDA-approved. In a 2020 trial, adding THC/CBD capsules to standard anti-nausea drugs raised the share of patients with no vomiting and no rescue medicine from 14% to 25%.

• Cancer pain: Not established. A 2023 Cochrane review found THC and THC/CBD spray were no better than placebo for cancer pain not controlled by opioids.

• Appetite and weight: Not established.

Good to know: Never use cannabis in place of cancer treatment. Tell your oncology team what you use; some cancer drugs interact with CBD .

What to ask for: For chemotherapy nausea, a THC-containing oral product, either THC alone or 1:1 THC:CBD capsules started the day before chemotherapy, as in the trials. Inhaled products work faster for breakthrough nausea.