What this means in practice
Anyone taking clobazam should tell their prescriber before adding cannabidiol from any source, because the sedation is the signal that the metabolite has climbed and the prescriber may need to lower the clobazam dose. Nothing changes for anyone not taking clobazam.
What people say
CBD is safe to take with anything. It is a plant compound, not a drug, so there is nothing for it to interact with, and it is sold on a shelf next to the vitamins for exactly that reason.
What the evidence supports
A dedicated 21-day pharmacokinetic trial in 20 patients with uncontrolled epilepsy found clobazam levels unchanged but its active metabolite raised about two- to three-fold (peak ratio 2.2, total exposure ratio 2.6). The approved product label reports the same effect at approximately threefold and instructs prescribers to consider cutting the clobazam dose if clobazam-type side effects appear. It is a documented interaction with measured human blood levels behind it, and a prescribing instruction written on the strength of it. What has not been shown is that the interaction occurs at the amounts people buy over the counter: the human data come from a prescription dose of 20 mg/kg/day, and no trial has tested a consumer-sized dose against clobazam.
How it is supposed to work
Cannabidiol blocks the liver enzyme CYP2C19, which is the route the body uses to clear away clobazam's active byproduct. Blocked, that byproduct builds up, and it is the part of clobazam most responsible for sedation.
Which way it runs
This one runs both ways, and calling it one-directional gets it wrong. Cannabidiol raises the blood level of clobazam's active metabolite, N-desmethylclobazam, roughly two to three times over, while leaving clobazam itself untouched. In the other direction, clobazam raises the level of cannabidiol's own active metabolite, 7-OH-cannabidiol, by about three quarters at peak. Each drug is amplifying the other's byproduct rather than the drug you can see on the prescription.
What is still missing
The popular claim is not that this interaction is small. It is that the category of thing cannot interact at all, and the approved label for cannabidiol carries a drug interactions section that says otherwise.
Sources
- A Phase 2, Double-Blind, Placebo-Controlled Trial to Investigate Potential Drug-Drug Interactions Between Cannabidiol and ClobazamVanLandingham KE, Crockett J, Taylor L, Morrison G, 2020
- EPIDIOLEX (cannabidiol) oral solution — US prescribing information, SPL version 35Jazz Pharmaceuticals, Inc., label revision 2026
- Cannabidiol efficacy and clobazam status: A systematic review and meta-analysisLattanzi S, Trinka E, Russo E, et al., 2020