Cannabis side effects in cancer patients most commonly affect the nervous system and mind

Across 152 studies, the most common adverse events were nervous system-related (118 studies), psychiatric (101 studies), and gastrointestinal (81 studies). THC-CBD combinations were the most common formulation studied (69 studies), followed by synthetic THC (47) and single-compound THC (42). Oral and inhalation were the primary administration routes.

Systematic scoping review following JBI methodology. Six databases searched from inception to May 2023. Included 152 primary studies: 61 RCTs, 26 non-randomized trials, 23 case reports, and other designs. All studies reported adverse events from cannabis-based products in cancer care settings.

With cancer patients increasingly using cannabis for symptom management, this is the most comprehensive mapping of adverse events to date. The finding of significant under-reporting in many studies highlights a critical gap that could lead to underestimating risks.

As cannabis use in cancer care grows, having a comprehensive picture of potential side effects is essential. This review reveals that while cannabis-related adverse events are common, the quality of reporting is often poor, making it difficult to accurately assess risks for specific patient populations.

Scoping review maps evidence but does not assess quality or pool effect sizes. Diverse study designs, patient populations, and cannabis products limit comparability. Under-reporting of adverse events in original studies means the true burden may be higher.