A review of human studies found strong evidence for CBD in refractory seizures and promising data for anxiety and schizophrenia, but weak or very weak evidence for most other conditions it is marketed for.
CBD consumers, clinicians fielding CBD questions, and anyone evaluating CBD product claims.
Strong evidence for seizures only; weak for most other claims
What the researchers found
Refractory seizure control has strong evidence. Acute CBD before anxiety-provoking events and chronic CBD for schizophrenia are promising but not proven. For most other conditions CBD is marketed for, evidence is weak or very weak. CBD is not risk-free: adverse effects include somnolence and GI symptoms, drug interactions occur, liver function test elevations have been documented, and potential effects on suicidal ideation need further study.
Why it matters
CBD products are widely available and marketed for dozens of conditions, but the gap between marketing claims and actual evidence is substantial. This review helps separate what is proven from what is speculative.
The numbers in context
No specific pooled statistics. Review covered FDA-approved Epidiolex and various non-FDA-approved CBD products. THC content threshold for legal CBD: <0.3%.
How the study worked
Review of human clinical studies evaluating CBD across multiple conditions, with assessment of evidence quality for each indication.
What this study cannot tell us
Narrative review. Evidence quality varies widely across conditions. Non-FDA-approved products have unknown quality, making it difficult to draw conclusions from studies using them.
How to read the evidence
Comprehensive review of human studies with honest assessment of evidence quality across conditions.
When this study was published
2019 review.
The bigger picture
The quality gap between FDA-approved CBD (Epidiolex) and unregulated CBD products means consumers may not be getting the dose or purity they expect, adding uncertainty beyond the already limited evidence.
Questions still open
- Will the promising anxiety and schizophrenia data hold up in larger trials? How significant are the liver function test elevations at commonly used doses?
Common questions
What conditions does CBD actually work for?
Is CBD safe?
Read the original research
A Review of Human Studies Assessing Cannabidiol's (CBD) Therapeutic Actions and Potential.
Journal of clinical pharmacology, 59(7), 923-934
Citation
White, C Michael. (2019). A Review of Human Studies Assessing Cannabidiol's (CBD) Therapeutic Actions and Potential.. Journal of clinical pharmacology, 59(7), 923-934. https://doi.org/10.1002/jcph.1387
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