More CBD did not mean fewer seizures, only more diarrhoea
Cannabidiol beat placebo by 19.5 percentage points at 10mg/kg/day and 19.9 at 20mg/kg/day, while quitting for side effects rose from 1.66 to 6.89 times placebo.
What the study found
Doubling the cannabidiol dose bought side effects, not seizure control
Pooled across four trials, cannabidiol beat placebo by 19.5 percentage points at 10mg/kg/day and 19.9 at 20mg/kg/day, while the risk of quitting for side effects rose from 1.66 to 6.89 times placebo. Doubling again, 25 to 50mg/kg/day, left benefit flat and diarrhoea rose from 31% to 56%.
The caveat · Doses never tested head to head
One trial does not fit cleanly: in Lennox-Gastaut syndrome the 20mg/kg/day arm ran about five percentage points ahead of the 10mg/kg/day arm on drop seizures. No trial here powered its two active doses against each other, so every dose comparison is descriptive rather than a tested difference.