A meta-analysis of 13 clinical studies found that CBD and THC produced small, statistically insignificant changes in circulating inflammatory markers (IL-6, IL-8, IL-10, TNF-alpha), challenging the widely promoted anti-inflammatory claims.
Clinical researchers, CBD consumers, physicians evaluating anti-inflammatory claims
Pooled effects of cannabinoids on all four inflammatory markers were trivial and non-significant
What the researchers found
Pooled estimates showed trivial and imprecise effects: IL-6 (SMD -0.17, p=0.41), IL-8 (SMD -0.30, p=0.06), IL-10 (SMD -0.10, p=0.79), and TNF-alpha (SMD -0.09, p=0.62). None reached statistical significance. Some individual trials in high-exposure or diseased populations reported reductions, but pooled effects were negligible. GRADE evidence certainty ranged from very low to moderate.
Why it matters
CBD and THC are widely marketed as anti-inflammatory, often based on preclinical data. This meta-analysis of actual human clinical trials shows that the anti-inflammatory effects observed in cells and animals have not consistently translated to measurable changes in human blood markers.
The numbers in context
IL-6: SMD -0.17 (CI: -0.56 to 0.23, p=0.41, I2=55%, n~129/arm); IL-8: SMD -0.30 (CI: -0.62 to 0.01, p=0.06, I2=0%, n~78/arm); IL-10: SMD -0.10 (CI: -0.83 to 0.63, p=0.79, I2=81%, n~92/arm); TNF-alpha: SMD -0.09 (CI: -0.45 to 0.27, p=0.62, I2=33%, n~105/arm); GRADE: very low to moderate
How the study worked
Systematic review and meta-analysis of 13 clinical studies meeting inclusion criteria. Random-effects models calculated standardized mean differences. Risk of bias assessed with RoB-2. Evidence certainty graded using GRADE methodology.
What this study cannot tell us
Only 13 studies met inclusion criteria with small sample sizes per meta-analysis, heterogeneous populations and dosing regimens, circulating biomarkers may not reflect tissue-level inflammation, GRADE certainty was low for several outcomes, publication bias possible
How to read the evidence
Systematic review with meta-analysis and GRADE assessment; limited by small number of eligible studies and heterogeneous designs
When this study was published
Published 2025
The bigger picture
The disconnect between strong preclinical anti-inflammatory evidence and trivial clinical effects raises important questions about dosing, bioavailability, and whether circulating markers capture the relevant anti-inflammatory activity of cannabinoids, which may be more localized.
Questions still open
- Are circulating biomarkers the right measure for cannabinoid anti-inflammatory effects? Would higher doses or specific formulations produce stronger effects? Does the anti-inflammatory action occur locally rather than systemically?
Common questions
Is CBD really anti-inflammatory?
Why might CBD work in the lab but not in blood tests?
Read the original research
The Pleiotropic Influence of Cannabidiol and Tetrahydrocannabinol on Inflammatory Biomarkers: A Systematic Review and Meta-Analytical Synthesis.
International journal of molecular sciences, 26(23)
Citation
Candeloro, Bruno Moreira; de Oliveira, Camila M; Gimenez, Fabiana Veronez Martelato; Barbosa, Marianne P C N; Soares, Beatriz Paiva; Ruiz, Ana C F; Folegatti, Derfel R M A; Barbalho, Sandra Maria; Oliveira, Nancy S; Porto, Andrey A; Garner, David Matthew; Sousa, Fernando H; Valenti, Vitor E. (2025). The Pleiotropic Influence of Cannabidiol and Tetrahydrocannabinol on Inflammatory Biomarkers: A Systematic Review and Meta-Analytical Synthesis.. International journal of molecular sciences, 26(23). https://doi.org/10.3390/ijms262311618
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