Weed might weaken cancer immunotherapy, cannabis doc says

Embargoed until: Publicly released: 2025-07-25 00:01

Australia; New Zealand

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Early research is suggesting that medicinal cannabis might make immunotherapy less effective at treating cancer, according to an editorial from a cannabis doctor in the NZ Medical Journal. These studies showed that patients who used cannabis had poorer responses to treatment and shorter survival times, but the research has several limitations, such as small sample sizes and other lifestyle differences like smoking. The NZ-born, Australia-based cannabis doctor also says from his experience that many immunotherapy patients will use edible forms of cannabis, unlike the smoked or inhaled forms used by the patients in the studies.

Media release

From: Pasifika Medical Association Group

Some cancer patients use medicinal cannabis to help with symptoms like pain, nausea or poor appetite. However, early studies suggest that using cannabis during immunotherapy—a type of treatment that helps the immune system fight cancer—might make the treatment less effective. These studies showed that patients who used cannabis had poorer responses to treatment and shorter survival times, but the research has several limitations, such as small sample sizes and other lifestyle differences like smoking. Most Australian patients take cannabis by mouth, unlike the inhaled forms used in these studies, so the results may not apply to everyone. More high-quality research is needed, and doctors should talk to their patients about the possible risks before combining cannabis with immunotherapy.

Journal/
conference: NZMJ

Organisation/s: Australani Health

Funder: Competing interests: Director—Vivienne Jansen Brains Research Pty Ltd. Director—Australani Health Pty Ltd. Director—Queensland Health Education, Medicine and Pharmaceuticals. Committee Member—Vitura Health Limited - Specialty Clinics Clinical Excellence. Committee Member—Gold Coast Primary Health Network - The Way Back Support Service Steering Committee. Patents: AU2019902462A0—Pain Relieving Medication, AU2019902162A0—A Cannabinoid Treatment For Ischaemia.

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