Adult Epilepsy CBD Outcomes: Treatment Retention and Confounding Matter

forensic toxicology working group members October 28, 2026 Forensic Toxicology

A retrospective series found substantial seizure reductions in some adults receiving CBD, alongside frequent adverse events. The findings describe selected clinical experience and do not isolate CBD’s independent effect from other treatment changes.

The cohort was specifically selected

The multicenter study reviewed 37 adults with Dravet syndrome, Lennox–Gastaut syndrome or tuberous sclerosis complex who had received at least 12 months of CBD treatment. These are specific severe epilepsy populations, not all adults with seizures.

The minimum treatment-history requirement matters when interpreting retention and tolerability. The analyzed group cannot automatically represent everyone who first attempted treatment.

Benefit and adverse events both occurred

Approximately 46% had at least a 50% seizure reduction at 12 months. Caregivers also reported subjective cognitive improvements in some patients. Those reports were not equivalent to a blinded neuropsychological demonstration.

Adverse events occurred in about 65%, and some led to later discontinuation. A characterization of tolerability must include those events rather than equating ‘mostly mild’ with ‘none.’

Why the effect cannot be isolated

There was no untreated or placebo comparison group. Concomitant antiseizure medications changed during follow-up, potentially contributing to both seizure outcomes and adverse effects. The authors also identified limitations in seizure-type and subgroup analyses.

Medical-writing support was funded by Jazz Pharmaceuticals, and authors disclosed industry relationships. These interests accompany the observational design in assessing the report.

The study supports further prospective investigation. It cannot provide a universally applicable response probability, establish the effect of an unrelated cannabis product or certify a patient’s functional capacity.