The short answer
In open-label epilepsy research, higher pharmaceutical CBD doses were associated with modestly higher topiramate levels. This did not establish toxicity or an automatic need to change the topiramate dose.
What this answer covers
Applies to oral systemic topiramate with pharmaceutical cannabidiol in refractory epilepsy, often alongside other antiseizure medicines.
- Supplement or preparation
- Cannabidiol
- Medication ingredient
- topiramate
Evidence and practical considerations
Absorption & effectiveness
Two human analyses support a modest conditional level increase; product, dose, and clinical response determine management.
- Exact scope
- cannabidiol (CBD) with topiramate
- Medication form and route
- oral systemic topiramate with pharmaceutical cannabidiol
- Timing or duration
- Observed during cannabidiol dose titration in an open-label expanded-access program; no universal dose threshold was established.
What remains uncertain
- A measurable level increase does not automatically require dose adjustment or prove toxicity.
Factors that may matter: CBD dose; topiramate dose; refractory epilepsy and polytherapy; age.
Read the supporting source summaries
Source 1: peer-reviewed open-label human pharmacokinetic study
pubmed.ncbi.nlm.nih.gov · Source check Jul 25, 2026
Population: Adults and children with refractory epilepsy receiving pharmaceutical cannabidiol and antiseizure drugs.
Topiramate serum levels increased significantly with increasing CBD dose; mean changes remained within accepted therapeutic ranges except for other named drugs.
Open-label, polytherapy, no randomized control, and clinical significance of the topiramate change was not established.
Source 2: peer-reviewed expanded-access final analysis
pmc.ncbi.nlm.nih.gov · Source check Jul 25, 2026
Population: 169 adults and children with refractory epilepsy.
Increasing CBD dose was associated with increased topiramate levels; non-clobazam changes were generally within accepted ranges and likely minor.
Open-label association, polytherapy, and no randomized clinical outcome test.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Research summary published |
Article revision: 40c0ed1a1c6218d8
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
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