Medical marijuana may improve symptoms of autism in children and young adults, a review suggests.
Researchers in Brazil found children and teenagers taking cannabidiol (CBD) orally as a liquid had ‘significant’ improvements in social skills and disruptive behaviors like aggression and tantrums.
CBD – a naturally occurring compound in cannabis – also helped autistic children sleep better and feel less anxious.
There was also no ‘significant difference’ in side effects like fatigue and appetite changes, suggesting CBD has a ‘favorable safety profile.’
This suggests CBD could be used in autism treatment plans alongside standard therapies, the researchers said.
Research suggests CBD activates molecules that bind to receptors in the brain responsible for regulating mood, stress, sleep, and brain development.
The experts cautioned more research is needed to fully understand the relationship between autism and medical cannabis.
Researchers at University of São Paulo in Brazil found medical cannabis may improve behaviors in autistic children and young adults (stock image)
Dr Lara Cappelletti Beneti Branco, lead investigator at University of São Paulo in Brazil, said: ‘The global population prevalence of ASD diagnosis amongst children and adolescents is growing, but many treatment pathways are not effective.
‘It is promising to see the effect of CBD cannabis extract on the study participants. However, there still needs to be considerable focus on further research with larger trials to clarify its efficacy and safety in managing ASD.’
According to the latest CDC data, one in 36 children in the US have autism – just under 2million.
In the early 2000s, this number was closer to one in 142.
Though it’s unclear what exactly could be behind the rise, experts have blamed environmental exposures like pollution, as well as doctors getting better at spotting the condition.
Unlike tetrahydrocannabinol (THC), the psychoactive compound in marijuana, CBD does not cause a ‘high’ or sense of euphoria.
CBD has been shown to improve conditions like epilepsy and other brain disorders, which experts suggest could be due to the same mechanism as treating autism.
According to the review abstract, presented this week at the 2025 European Congress of Psychiatry, researchers analyzed three studies involving 276 total children and young adults with autism.
Participants ranged from five to 21 years old, and the average age was 10. More than two-thirds of the participants were male.
The patients received either a gradually increasing dose of CBD or a placebo.
The dosage started at one milligram per kilogram of body weight and gradually went up to 10 milligrams per kilogram of body weight.
CBD gummies sold in the US can contain anywhere from five to 120 milligrams per gummy.
It’s unclear if the CBD was the same type sold at health stores in the US or if it was a specific medical grade.
The team found children and young adults taking CBD had ‘significantly enhanced social responsiveness,’ meaning they were better able to understand social cues and maintain conversations.
The participants also had ‘moderate’ improvements in disruptive behaviors like tantrums and sleep and ‘small yet notable reductions’ in anxiety.
The researchers wrote: ‘These findings support the potential consideration of CBD cannabis extracts in ASD treatment plans.
‘However, the review’s limitations include a small number of studies, limited sample sizes, and significant heterogeneity.
‘Future research with larger, robust trials is needed to clarify the efficacy and safety of CBD cannabis extracts in managing ASD.’
The above map shows states that have medical cannabis programs in the US. Medical cannabis is legal in 47 states, Washington DC, and three territories
Experts believe CBD could lead to improvements in autistic behaviors by activating endocannabinoids, molecules that bind to cannabinoid receptors in the brain, spinal cord, gastrointestinal tract, and immune system.
This could influence functions like mood, anxiety, metabolism, sleep, and pain.
Last year, a similar study in the journal Pharmaceuticals found CBD improved communication skills, attention, learning, eye contact, irritability, and overall quality of life in autistic people ages five to 18 after six months.
Medical cannabis is legal in 47 states, the District of Columbia, and the US territories Guam, Puerto Rico, and the US Virgin Islands, according to the CDC.
While cannabis for medical use is legal in the UK with a prescription, it is a controlled substance and is illegal to possess, produce, supply, import, or export, according to the House of Commons Library.
Only patients with Dravet syndrome, Lennox-Gastaut syndrome, multiple sclerosis, and nausea from chemotherapy can get a prescription for medical cannabis through the NHS.
Professor Geert Dom, president of the European Psychiatric Association, said: ‘ASD can be extremely frustrating for all involved; parents of children and adolescents with the disorder, the treating clinicians and of course the children and adolescents themselves.
‘A large part of this frustration is down to finding a viable treatment option that works to reduce symptoms.
‘It is with delight that we see the results of this meta-analysis and we hope to see further research into this so we can move towards a solution to the unmet need within this community.’
The link between cannabis and autism is complicated and still not well understood.
For example, some evidence suggests using cannabis during pregnancy may cause genetic changes in unborn babies, increasing their risk of autism and ADHD.
However, autism advocacy groups have said the causes of autism are not fully understood and many experts suggest there isn’t one specific cause.
