CBD and ADHD: one controlled trial, and it was negative

ADHD brings together three kinds of difficulty: inattention, motor hyperactivity and impulsivity. France's national health insurance counts it as a disorder only when these symptoms last more than 6 months. It affects 5% of under-18s and 3% of adults, appears to be twice as common in boys, and is probably under-recognised in girls.

ADHD is a neurodevelopmental disorder, and diagnosing and managing it is the work of health professionals. This article reports what research has measured and does not replace medical advice.

The EMA-C trial, run at King's College London, appeared in 2017 in European Neuropsychopharmacology. To date it is the only randomised controlled trial of cannabinoids in ADHD to be published. It tested Sativex, a mouth spray combining THC and CBD, so CBD was never given alone.

Its protocol was as follows:

The trial missed its primary outcome: the difference from placebo could be due to chance. The analysis also included only 11 people in the placebo group.

On secondary outcomes, the authors report a "nominally significant" improvement in hyperactivity and impulsivity (p = 0.03). The signal disappears after correction for multiple comparisons, a calculation that adjusts for the number of tests run. The authors treat it as a preliminary lead that justifies more studies, and it does not prove efficacy.

In 2019, a meta-analysis in The Lancet Psychiatry pooled 83 studies, including 40 randomised trials, across six psychiatric disorders. It found just 3 studies on ADHD, with a single randomised trial of 30 participants, EMA-C. The authors conclude that there is scarce evidence that cannabinoids improve ADHD.

In 2023, a review in Pharmacology Biochemistry and Behavior examined the 9 published randomised trials of CBD in neurodevelopmental disorders, covering ADHD, autism, intellectual disability and Tourette syndrome. It judged the results too inconsistent to guide clinical use, and the authors describe CBD's place in these disorders as "largely undetermined".

The same conclusion holds for most proposed uses, as our review of what clinical studies say about CBD shows.

In September 2026, the international registry ClinicalTrials.gov listed five trials of cannabinoids in ADHD. Only one has been completed and published. An Israeli trial of cannabis oils stopped after 8 participants because recruitment was poor.

The three ongoing trials test different things:

• an Israeli trial gives 120 children and adolescents aged 6 to 18 a terpene-enriched CBD oil or a placebo;
• an American trial in 76 adults measures how a single 80 mg dose of CBG affects attention and memory tests;
• a Brazilian trial gives 60 adolescents aged 12 to 17 an extract containing CBG, CBD and also THC.

None has published results. Two concern CBG, another hemp molecule, which our page on CBG describes. No registered trial studies THCV in ADHD; our article on THCV covers this cannabinoid.

The Haute Autorité de santé guideline of 23 September 2024 on ADHD in children and adolescents sets out multimodal care: psychoeducation, parent programmes and behavioural therapies. Where a medicine is indicated, extended-release methylphenidate comes first, always combined with these measures. Cannabis and CBD do not appear in the text.

Epidyolex has been the only cannabidiol-based medicine authorised in the European Union since 19 September 2019. Its indications cover seizures linked to three rare diseases, Lennox-Gastaut syndrome, Dravet syndrome and tuberous sclerosis complex, and ADHD is not among them. Our article on Epidyolex describes those trials.

Three more points concern anyone affected:

• In a press release of 19 June 2025, the ANSM and Anses warn that CBD taken with certain medicines can make them less effective or increase their side effects. Talk it over with the doctor who prescribes them; our article on drug interactions explains the mechanism.
• The same release cites a 2023 study in which 8 CBD products out of 10 did not contain the amount on the label. It also reports several hundred poisonings since early 2024, most often caused by undeclared THC or synthetic cannabinoids.
• A 2024 meta-analysis estimates that 26.9% of people with ADHD have a cannabis use disorder at some point in their lives, a risk 2.85 times higher than in the general population. The work concerns THC-rich cannabis and says nothing about CBD.

Dedicated articles cover the side effects of CBD and what can be said about concentration.