Published summary: 2026-03-07
Where the evidence converges
Meta-analysis of 30 trials found cannabinoids significantly outperformed older anti-nausea drugs for chemotherapy, with nearly half of 1,138 patients preferring cannabinoids despite more side effects
Strong evidence · 46 studies
Many included trials were from the 1980s-1990s and used outdated comparator drugs (neuroleptics rather than modern anti-emetics like ondansetron). Some individual trials had small samples. The increas
Meta-analysis of 11 RCTs finding selective cannabinoids provide a small but significant reduction in neuropathic pain (-0
Strong evidence · 46 studies
High heterogeneity across studies. The effect size is small and may not be clinically meaningful for all patients. Studies varied in cannabinoid type, dose, and neuropathic pain etiology. The search e
Meta-analysis of 550 patients found CBD reduced seizures by ~20 percentage points in severe childhood epilepsies
Strong evidence · 46 studies
Only four trials available, all in LGS and DS specifically. Results may not generalize to other epilepsy types. All trials used pharmaceutical-grade CBD (Epidiolex), so findings do not apply to unregu
Where questions remain
In a landmark NEJM trial, oral THC prevented chemotherapy vomiting in 80% of completed courses versus 0% for placebo, with no vomiting during subjective highs
Moderate evidence · 289 studies
Small sample of 22 patients with only 20 evaluable. The abstract does not specify the THC dose. Crossover design means carryover effects are possible. Published in 1975, before modern antiemetic drugs
A 1978 medical review identified cannabis as promising for glaucoma and asthma but flagged cardiovascular risks during exercise and preliminary concerns about lung and immune effects
Moderate evidence · 289 studies
As a narrative review from 1978, it reflects limited evidence available at that time. The cannabis landscape has changed dramatically in terms of product potency, consumption methods, and the volume o
A 1981 critical review found THC showed promise against chemotherapy nausea but identified significant gaps in safety and pharmacological knowledge
Moderate evidence · 289 studies
The review itself acknowledged that the evidence base had significant deficiencies. As a review from 1981, it predates decades of subsequent antiemetic research including modern serotonin antagonists
Data from 120 subjects showed cannabis tolerance develops and fades quickly, while withdrawal symptoms including insomnia, irritability, and tremor appeared after as few as 7 days of use
Moderate evidence · 289 studies
Data from controlled research settings may not reflect real-world usage patterns. The 120 subjects likely represented a relatively homogeneous population. Withdrawal was described as mild and transien
Research gaps
- Long-term prospective studies tracking outcomes over 5+ years are largely absent from the literature.
- Research on diverse populations (different ages, ethnicities, and medical backgrounds) remains limited.
Key studies
Nearly 29% of North Americans have tried CBD, about double the rate in Europe
Despite the explosive growth of the CBD market, no prior systematic assessment of how many people actually use CBD existed. These numbers provide a baseline for tracking trends as regulations and products evolve.
Cannabis products with THC showed small pain improvements with significant side effects, while CBD alone did not help
This is the most current synthesis of cannabis for pain, showing benefits are small and limited to THC products while CBD alone does not help.
Meta-analysis found cannabis use disorder linked to more complications and higher costs after hip and knee replacements
Joint replacement is one of the most common elective surgeries. With cannabis use disorder increasing alongside legalization, this meta-analysis quantifies the specific complications orthopedic surgeons should watch for and discuss with patients.
Cannabinoid Medicines Are Generally Safe for Older Adults, With Dose-Dependent Side Effects
Older adults are the fastest-growing demographic of cannabinoid medicine users, yet most safety data comes from younger populations. This meta-analysis specifically addresses the 50+ age group, providing age-appropriate safety data for clinical decision-making.
Major meta-analysis of 152 RCTs finds cannabinoid effectiveness varies dramatically by specific drug and condition
By analyzing cannabinoid medications separately rather than lumping them together, this study reveals that the question "does cannabis work?" is misleading. The answer depends entirely on which cannabinoid and which condition.
Meta-analysis confirmed CBD reduces seizures by 33% in treatment-resistant epilepsy
This meta-analysis provides the strongest quantitative evidence to date supporting CBD as an add-on treatment for three of the most difficult-to-treat pediatric epilepsy syndromes.
How the research developed
Pre-2000
37 studies published. Includes 8 RCTs, 1 strong-evidence studies.
2000–2009
118 studies published. Includes 1 meta-analyses, 21 RCTs, 15 strong-evidence studies.
2010–2014
130 studies published. Includes 23 RCTs, 13 strong-evidence studies.
2015–2019
379 studies published. Includes 7 meta-analyses, 14 RCTs, 37 strong-evidence studies.
2020–present
1027 studies published. Includes 28 meta-analyses, 75 RCTs, 76 strong-evidence studies.
How this summary was assembled
This consensus synthesizes 1691 peer-reviewed studies: 36 meta-analyses (2%), 141 randomized controlled trials (8%), 419 observational studies (25%), 594 reviews (35%), 64 case studies (4%), 437 other study types (26%). Studies span from the earliest available research through 2025. Evidence strength ratings reflect study design, sample size, and replication across multiple research groups.
These counts describe the source summary at publication. They may differ from the current library.