One in Four Epilepsy Patients Developed Tolerance to CBD Treatment
Among 92 patients with treatment-resistant epilepsy using CBD-enriched oil, 25% developed tolerance (reduced effectiveness) after an average of 7.3 months, with patients who had shorter epilepsy duration more likely to develop tolerance.
Quick Facts
What This Study Found
Of 84 patients analyzed for tolerance (treated at least 3 months), 21 (25%) developed tolerance after a mean of 7.3 months. Overall responder rate was 54% (>50% seizure reduction), and 9% became seizure-free. Shorter epilepsy duration was negatively correlated with tolerance development (p=0.038).
Key Numbers
92 patients; mean age 11.8 years; mean follow-up 19.8 months; mean CBD dose 11.3 mg/kg/day; 31% discontinued; 51% had adverse reactions; 54% responder rate; 9% seizure-free; 25% developed tolerance at mean 7.3 months; shorter epilepsy duration associated with tolerance.
How They Did This
Prospective study of 92 consecutive patients (age 1-37, mean 11.8 years) with treatment-resistant epilepsy treated with CBD-enriched oil (CBD:THC 20:1), with tolerance defined as either need for >30% dose increase or >30% increase in seizure frequency after at least 3 months of stable treatment.
Why This Research Matters
This is the first study to systematically report tolerance to CBD in epilepsy patients. If one in four patients loses treatment benefit over time, it has significant implications for long-term seizure management.
The Bigger Picture
Tolerance development could limit the long-term clinical utility of CBD for epilepsy, suggesting that dosing strategies, drug holidays, or combination approaches may need to be developed to maintain efficacy over time.
What This Study Doesn't Tell Us
Single-center study; open-label design without placebo comparison; tolerance definition was operationalized rather than biologically confirmed; variable CBD-enriched oil formulations.
Questions This Raises
- ?Can tolerance be overcome with dose adjustments or treatment breaks?
- ?Does tolerance to pharmaceutical-grade CBD (Epidiolex) develop at similar rates?
Trust & Context
- Key Stat:
- 25% of patients developed tolerance to CBD after an average of 7.3 months
- Evidence Grade:
- Prospective open-label study providing moderate evidence of tolerance development, limited by lack of placebo control and single-center design.
- Study Age:
- Mean follow-up of 19.8 months (range 3-45 months).
- Original Title:
- Cannabidiol-enriched oil in children and adults with treatment-resistant epilepsy-does tolerance exist?
- Published In:
- Brain & development, 43(1), 89-96 (2021)
- Authors:
- Uliel-Sibony, Shimrit(2), Hausman-Kedem, Moran(2), Fattal-Valevski, Aviva(2), Kramer, Uri
- Database ID:
- RTHC-03585
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does CBD stop working over time?
In this study, 25% of epilepsy patients showed signs of tolerance to CBD after an average of 7.3 months, meaning the treatment became less effective. This is the first systematic report of CBD tolerance in epilepsy.
Who is more likely to develop tolerance?
Paradoxically, patients with shorter epilepsy duration were more likely to develop tolerance. The reasons for this are unclear and require further investigation.
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Cite This Study
https://rethinkthc.com/research/RTHC-03585APA
Uliel-Sibony, Shimrit; Hausman-Kedem, Moran; Fattal-Valevski, Aviva; Kramer, Uri. (2021). Cannabidiol-enriched oil in children and adults with treatment-resistant epilepsy-does tolerance exist?. Brain & development, 43(1), 89-96. https://doi.org/10.1016/j.braindev.2020.06.018
MLA
Uliel-Sibony, Shimrit, et al. "Cannabidiol-enriched oil in children and adults with treatment-resistant epilepsy-does tolerance exist?." Brain & development, 2021. https://doi.org/10.1016/j.braindev.2020.06.018
RethinkTHC
RethinkTHC Research Database. "Cannabidiol-enriched oil in children and adults with treatme..." RTHC-03585. Retrieved from https://rethinkthc.com/research/uliel-sibony-2021-cannabidiolenriched-oil-in-children
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.