Cannabis for Autism: First Major Trial Shows Mixed Results
What Researchers Found About Autism and Cannabis
The Study at a Glance
Published
Molecular Autism, 2021
Researchers
Multiple institutions (International)
Study Type
Randomized Controlled TrialParticipants
150 patients · 12 weeks treatment + 4-week washout + 12 weeks crossover
Key Finding
Evidence for efficacy of these cannabinoid interventions in autism spectrum disorder are mixed and insufficient. Further testing of cannabinoids in ASD is recommended.
Key Finding: Evidence for efficacy of these cannabinoid interventions in autism spectrum disorder are mixed and insufficient. Further testing of cannabinoids in ASD is recommended.
What Researchers Studied About Autism and Cannabis
Endocannabinoid dysfunction in animal models of autism spectrum disorder (ASD) and anecdotal evidence for efficacy in humans motivated this trial.
This was a placebo-controlled, double-blind comparison of two oral cannabinoid solutions in 150 participants aged 5-21 years with ASD.
Two formulations were tested: 1. BOL-DP-O-01-W: whole-plant cannabis extract with CBD:THC at 20:1 ratio 2. BOL-DP-O-01: purified cannabidiol and THC at the same 20:1 ratio
How This Randomized Controlled Trial Was Conducted
Participants received either placebo or cannabinoids for 12 weeks (testing efficacy), followed by a 4-week washout and predetermined crossover for another 12 weeks to further assess tolerability.
Primary outcome measures were: (1) Home Situation Questionnaire-ASD (HSQ-ASD) and (2) Clinical Global Impression-Improvement scale with disruptive behavior anchor points (CGI-I).
Secondary measures included Social Responsiveness Scale (SRS-2) and Autism Parenting Stress Index (APSI).
Autism Treatment Results
The Main Results:
- 1PRIMARY OUTCOME (HSQ-ASD Total Score): Did NOT differ among groups
- 2PRIMARY OUTCOME (APSI): Did NOT differ among groups
- 3CO-PRIMARY (CGI-I disruptive behavior): 49% "much/very much improved" on whole-plant vs 21% placebo (P = 0.005)
- 4SECONDARY (SRS Total Score): Improved 14.9 points on whole-plant vs 3.6 on placebo (P = 0.009)
- 5No treatment-related serious adverse events
- 6Common adverse events: somnolence (28% whole-plant, 23% pure, 8% placebo)
- 7Decreased appetite: 25% whole-plant, 21% pure, 15% placebo
By the Numbers
| Statistic | What It Means |
|---|---|
| 150 participants | Children and young adults with ASD aged 5-21 years |
| 49% vs 21% | Much/very much improved on disruptive behavior (whole-plant vs placebo, P = 0.005) |
| 14.9 vs 3.6 | Point improvement on Social Responsiveness Scale (whole-plant vs placebo, P = 0.009) |
| 20:1 | CBD to THC ratio used in both cannabinoid formulations |
Children and young adults with ASD aged 5-21 years
Much/very much improved on disruptive behavior (whole-plant vs placebo, P = 0.005)
Point improvement on Social Responsiveness Scale (whole-plant vs placebo, P = 0.009)
CBD to THC ratio used in both cannabinoid formulations
What This Means for Autism Patients
This is one of the largest randomized trials of cannabinoids for autism, and the results are mixed.
The primary outcomes (overall behavioral problems and parenting stress) showed no difference between cannabinoids and placebo. This means the treatment did not meet its main goals.
However, two secondary outcomes were positive: disruptive behavior improved more with whole-plant cannabis extract (49% vs 21%), and social responsiveness scores improved significantly.
The treatment was well-tolerated with no serious adverse events, though somnolence and decreased appetite were more common with cannabinoids.
The researchers concluded that "evidence for efficacy is mixed and insufficient" and recommend further testing. This is not yet a proven treatment for autism.
Quick Answers: Autism and Cannabis
Direct answers based on the findings of this study:
Research Summary: Answers are based on published peer-reviewed studies and represent research findings, not medical recommendations. Individual results may vary. Always consult a healthcare provider before making treatment decisions.
Does medical marijuana help autism?
Mixed results in the largest trial. Primary outcomes showed no benefit over placebo, but disruptive behavior improved significantly more with whole-plant cannabis extract (49% vs 21%, P=0.005). Researchers said evidence is "mixed and insufficient."
Source: Aran et al., Molecular Autism, 2021 (PMID: 33536055)
Is cannabis safe for children with autism?
Well-tolerated with no serious adverse events. Common side effects included sleepiness (28% on whole-plant vs 8% placebo) and decreased appetite (25% vs 15%). The 20:1 CBD:THC ratio was well-tolerated in the largest autism cannabis trial (150 patients).
Source: Aran et al., Molecular Autism, 2021 (PMID: 33536055)
Is there scientific evidence for cannabis treating autism?
Evidence is mixed. A 150-person RCT found primary outcomes (behavioral problems, parenting stress) showed no benefit. However, secondary measures of disruptive behavior and social responsiveness significantly favored cannabinoids. More research is needed.
Source: Aran et al., Molecular Autism, 2021 (PMID: 33536055)
This is educational content, not medical advice
The research summarized here is for informational purposes only. Individual results may vary, and what works in studies may not work the same way for everyone. Always consult with a qualified healthcare provider before making changes to your treatment plan or starting medical cannabis therapy.
Important Limitations
This study has some caveats to keep in mind when interpreting the results:
- Primary outcomes were not met
- Lack of pharmacokinetic data
- Wide range of ages (5-21 years) and functional levels
- Cannot determine which specific symptoms benefit most
- Crossover design may have carryover effects
The Bottom Line on Cannabis for Autism
This 150-person trial of cannabinoids for autism found mixed results. The primary outcomes (behavioral problems, parenting stress) showed no benefit over placebo. However, secondary measures of disruptive behavior (49% vs 21% improved, P=0.005) and social responsiveness (P=0.009) favored the whole-plant cannabis extract. The treatment was well-tolerated. Researchers concluded evidence is "mixed and insufficient" and more research is needed.
Do You Qualify for Medical Marijuana?
If you're living with Autism, you may qualify for a medical marijuana card. Our licensed physicians can evaluate you from home via telehealth.
Related Research & Resources
Related Research
Condition Research
Get Your Card
This condition qualifies for medical marijuana in:
Source
Aran A, Harel M, Cassuto H, et al. "Cannabinoid treatment for autism: a proof-of-concept randomized trial" Molecular Autism. 2021. DOI: 10.1186/s13229-021-00420-2
Important Information
Not Medical Advice: This research summary is for educational purposes only. It should not be used to diagnose, treat, cure, or prevent any disease or medical condition. Always consult a qualified healthcare provider before starting or changing any treatment.
Individual Variation: Research findings represent group averages. Your individual response to cannabis may differ based on genetics, other medications, underlying conditions, and many other factors.
Last reviewed: January 25, 2026
Important Notices
Research Summary Disclaimer
This content represents our interpretation of published scientific research for educational purposes. It should not be used to make treatment decisions without consulting a qualified healthcare provider. Individual results may vary from study findings.
FDA Notice
These statements have not been evaluated by the FDA. Cannabis is not intended to diagnose, treat, cure, or prevent any disease. The FDA has not approved cannabis for any medical condition except specific prescription medications.
Copyright & Fair Use
Research summaries are provided under fair use (17 U.S.C. § 107) for educational purposes. We provide brief summaries with attribution, not full reproductions. All studies remain the intellectual property of their respective authors and publishers.
Data Sources
Study information sourced from PubMed®, U.S. National Library of Medicine. Inclusion does not imply endorsement by NLM, NIH, or the federal government.
For complete information, see our Terms of Use and Research Content Policy.
FAQs: Cannabis for Autism
Does cannabis help autism?
Mixed results. Primary outcomes showed no benefit, but disruptive behavior improved more with whole-plant cannabis (49% vs 21%, P=0.005). Researchers concluded evidence is "mixed and insufficient" and more research is needed.
Is CBD safe for children with autism?
Well-tolerated with no serious adverse events. Common side effects included sleepiness (28% vs 8% placebo) and decreased appetite (25% vs 15% placebo). The 20:1 CBD:THC ratio was well-tolerated in 150 participants aged 5-21.
What type of cannabis was used for autism in this study?
Two formulations were tested: whole-plant cannabis extract and purified cannabinoids, both with a 20:1 CBD to THC ratio. The whole-plant extract showed slightly better results on secondary outcomes.