CBD and ADHD: what the research has actually measured

ADHD combines inattention, motor hyperactivity and impulsivity, over at least six months and with a functional impact. The Assurance Maladie indicates that it affects around 5% of under-18s and 3% of adults, with a frequency roughly twice as high in boys and probable under-diagnosis in girls.

It is a neurodevelopmental disorder, managed by healthcare professionals. Personal questions belong with a doctor, and this article is not intended to guide any care decision.

A team at King's College London published in 2017, in European Neuropsychopharmacology, the only randomised controlled trial of cannabinoids in ADHD. One clarification is needed straight away: the product tested was not cannabidiol, but an oral spray combining THC and CBD in a 1 to 1 ratio — in other words, a medicine containing THC.

The trial was single-centre, double-blind against placebo, over six weeks, in 30 adults split into two groups of fifteen. The primary endpoint covered cognitive performance and activity level measured by a standardised test.

The result is negative: the estimate was minus 0.17, with a 95% confidence interval running from minus 0.40 to 0.07, for a p-value of 0.16. No significant difference from placebo.

Signals appeared on secondary endpoints, notably hyperactivity and impulsivity. None survived correction for multiple testing, which is precisely the definition of a result that cannot be relied upon. Presenting them as promising would be a faulty reading.

A meta-analysis published in 2019 in The Lancet Psychiatry, covering 83 studies and 40 randomised trials across six psychiatric disorders, identified only three studies for ADHD, including a single randomised trial of 30 participants. No pooled estimate was possible. Its authors conclude that the evidence suggesting an improvement of ADHD by cannabinoids is scarce.

A systematic review published in 2023 in Pharmacology Biochemistry and Behavior, devoted to trials of cannabidiol in neurodevelopmental disorders, retains nine randomised trials across all disorders combined and judges the signals too inconsistent to guide clinical use, the place of cannabidiol remaining largely undetermined.

There is, moreover, no Cochrane review devoted to cannabinoids in ADHD. That absence is an observation, not evidence in the opposite direction.

A search of the international clinical trials registry, in August 2026, shows no completed trial of cannabidiol alone in ADHD. One trial conducted on cannabis oils was stopped after eight participants for lack of recruitment. The ongoing trials will not read out their results before the end of 2026, and two of them concern cannabigerol, a different molecule.

In other words, the question of cannabidiol on its own in ADHD is, to date, addressed head-on by no completed trial.

The clinical practice guideline published by the Haute Autorité de santé in September 2024 on ADHD in children and adolescents retains prolonged-release methylphenidate as the first-line pharmacological option. It mentions neither cannabis nor cannabidiol.

On the medicines side, the only cannabidiol-based speciality authorised in the European Union is Epidyolex, whose validated indications concern rare epilepsies. ADHD is not among them.

One safety point deserves mention, finally. In a joint statement of 19 June 2025, the ANSM and Anses report several hundred poisonings since the start of 2024 among consumers of products presented as containing CBD, most often linked to the undisclosed presence of THC or synthetic cannabinoids. The same statement notes that a 2023 study found a CBD content different from the labelling for 8 products out of 10, and recalls that CBD combined with certain medicines can reduce their effectiveness or increase their adverse effects. The subject is developed in our articles on drug interactions and on side effects.

Let us end by noting a result that points the other way. A meta-analysis published in 2024 in the Journal of Psychiatric Research reports a markedly increased prevalence of cannabis use disorder among people with ADHD, at 26.9% over the lifetime, a risk around 2.85 times higher than in the general population. That work concerns THC-rich cannabis and not cannabidiol, and the two must not be confused. Our articles on concentration, on brain fog and on sleep address neighbouring subjects within the same non-medical framework.

Is there a clinical trial of CBD alone in ADHD?

No. A search of the international clinical trials registry in August 2026 shows no completed one. The only published randomised trial involved a medicine combining THC and CBD, in 30 adults, over six weeks, and its primary endpoint was negative with a p-value of 0.16.

What are the secondary results of that trial worth?

They cannot be presented as conclusive. The signals observed on hyperactivity, impulsivity and cognitive inhibition did not survive correction for multiple testing, which means they are not distinguishable from chance given the number of comparisons performed.

Does the Haute Autorité de santé mention CBD for ADHD?

No. Its September 2024 clinical practice guideline on ADHD in children and adolescents mentions neither cannabis nor cannabidiol, and retains prolonged-release methylphenidate as the first-line pharmacological option. No health authority recommends cannabidiol in this indication.