Cannabinoid reference entry
CBD
CBD has more than one evidence story
CBD is cannabidiol, a phytocannabinoid distinct from THC. The NHS describes the CBD in the licensed epilepsy medicine Epidyolex as not producing the high associated with THC. That description belongs to a named medicine and formulation. It should not be extended automatically to every product sold with CBD on the label.
The clearest clinical results are indication-specific
Two randomised trials in severe childhood epilepsies provide the strongest human evidence cited here. In Dravet syndrome, purified CBD was added to existing anti-seizure treatment and reduced convulsive-seizure frequency more than placebo. In Lennox-Gastaut syndrome, purified CBD was studied for drop seizures. Neither trial tested general pain, sleep or anxiety, and neither used a retail CBD oil or an uncharacterised cannabis profile. The CBD and THC comparison page covers the related label distinction.
Safety findings sit alongside those results
The Dravet safety and pharmacokinetic trial recorded an interaction involving the active clobazam metabolite. It also recorded liver-transaminase elevations in some participants taking valproate. Those are findings from monitored participants using the tested formulation. They are a reason to give the clinical team a complete medicines list, not a basis for predicting an interaction or changing treatment without review.
An animal study reported reduced glial reactivity and antipsychotic-like behaviour in a schizophrenia-related model. That is a separate preclinical question from the epilepsy trials and does not establish an antipsychotic effect in people.
A CBD label still needs its preparation attached
The amount printed on a label describes that product or batch. It does not make it equivalent to purified pharmaceutical CBD. The MHRA treats medical claims as a medicines-regulatory issue, while the Home Office distinguishes pure isolated CBD from preparations containing controlled cannabinoids. Product status therefore depends on the preparation and its claims, not the three letters CBD alone.
Related conditions
Sources
- Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome (human randomised clinical trial, 2017).
- Cannabidiol in patients with seizures associated with Lennox-Gastaut syndrome (human randomised clinical trial, 2018).
- Randomized, dose-ranging safety trial of cannabidiol in Dravet syndrome (human clinical pharmacology, 2018).
- Decreased glial reactivity could be involved in the antipsychotic-like effect of cannabidiol (animal research, 2015; DOI 10.1016/j.schres.2015.01.015).
- MHRA statement on products containing cannabidiol (MHRA, 2025).
- Drug licensing factsheet: cannabis, CBD and other cannabinoids (Home Office, 2024).
For a plain-English glossary explanation, read CBD.