This article covers what research shows about cannabis for ADHD (attention-deficit/hyperactivity disorder). It also covers what is missing from every study on ADHD, autism and Tourette syndrome, and what the rules are in Thailand. None of it is a treatment recommendation.
Part 1 found that the Tourette syndrome trials were small, mixed and all in adults. The best autism trial included 150 children and young people. One of its two main measures was negative and the other was positive, and it measured behaviour, not autism itself.
Read this first.
This article is not medical advice. It does not recommend giving cannabis to any child. Treatment decisions for a child with one of these conditions belong to a specialist who knows the child. That means a paediatrician, a child psychiatrist or a paediatric neurologist (a doctor for children’s brain and nerve conditions).
Nobody knows the long-term effects of cannabinoids on the developing brain. Cannabinoids are the active compounds in cannabis. Separately, large population studies link cannabis use in the teenage years with a higher risk of psychosis. Psychosis is a mental illness in which a person loses touch with reality.
This article gives no doses. Be sceptical of anyone who does.
Translator’s note: In Thailand, cannabis flower is a controlled herb. It may be sold only against a PT 33 (ภ.ท.33) prescription from an authorised practitioner. Using it for a minor is a decision for a specialist.
This is Part 2. Part 1: Cannabis and Neurodevelopmental Conditions in Children: ADHD, Autism and Tourette Syndrome — What the Trials Show and What They Cannot
Research Words Used in This Part
- Randomised controlled trial (RCT) and placebo. Participants are split into two groups by chance. One group gets the real product. The other gets a placebo, which is a dummy that looks the same.
- Pilot trial. A small first trial that tests whether a larger trial is workable. Its results are a hint, not proof.
- Primary outcome. The main measure, chosen before the trial starts, that decides whether the product worked. Secondary outcomes are extra measures with less weight.
- p-value. An estimate of how often a difference this large would appear by luck alone if the product did nothing. By convention, about 0.05 or lower counts as “significant”.
- Intention-to-treat analysis. Everyone is counted in the group they were assigned to, including people who dropped out. This gives a fairer picture than counting only those who finished.
- Adjustment for multiple testing. When researchers check many measures, a few will look positive by luck. Adjustment raises the bar to allow for this. A result that does not survive adjustment is weak.
4. ADHD
ADHD affects attention, activity level and impulse control.
The claim about how cannabis would work
Some campaign writing that promotes cannabis argues that low dopamine is one of the causes of ADHD. Dopamine is a brain chemical involved in attention and reward. Low dopamine would explain why stimulant medicines, which raise dopamine, work for ADHD.
The same writing then suggests that the body makes its own cannabinoids to protect against ADHD symptoms. It says this is why people with ADHD report feeling better with cannabis.
The first part is a recognised scientific model. The second part is a hypothesis presented as if it were an explanation. No evidence shows that the body’s own cannabinoid system (the endocannabinoid system) works as a protective response in ADHD.
The only trial: Cooper and colleagues, 2017
Cooper and colleagues ran a pilot RCT of nabiximols against placebo in 30 adults with ADHD: 15 on nabiximols and 15 on placebo. Nabiximols is a prescription mouth spray made from cannabis extract that contains both THC and CBD.
- Primary outcome: no significant difference in the intention-to-treat analysis. The measure was the QbTest, a computer test of attention, impulsivity and restlessness. The nabiximols group generally scored better, but the p-value was 0.16.
- Secondary outcomes: hyperactivity/impulsivity improved (p = 0.03). So did cognitive inhibition, which is the ability to stop an automatic response (p = 0.05). Both counted as significant only before adjustment.
- Inattention and emotional lability (fast mood swings) showed trends that were not significant. None of the secondary results survived adjustment for multiple testing.
- The authors’ conclusion: the results are preliminary evidence for the self-medication theory of cannabis use in ADHD. They called for more study of the endocannabinoid system in ADHD.
Read carefully what the authors concluded, and what they did not. The self-medication theory says people with ADHD use cannabis because it makes them feel better. Support for that theory is not evidence that cannabis is an effective ADHD treatment. This trial was also in adults.
The argument about current ADHD medicines
The same campaign writing criticises how ADHD is treated today. It points out that methamphetamine is approved for ADHD under the brand name Desoxyn by the FDA, the US medicines regulator. It also notes that parents and professionals worry about the side effects of widely prescribed stimulants.
These are real concerns about how ADHD is treated. But being unhappy with one treatment is not evidence for another one. The same argument appears elsewhere in medical cannabis campaigning.
Treat “cannabis helps ADHD” as unproven. If an adult you know with ADHD already uses cannabis, encourage them to tell their doctor. The doctor can then check for interactions with their other medicines.
5. What the Studies on All Three Conditions Lack
Every study in Parts 1 and 2 has the same gaps. These gaps matter more for children than for anyone else.
Duration. No treatment period lasted longer than about three months. These conditions last a lifetime. Families need to know what happens over years, and no study has followed anyone that long.
Age. The Tourette syndrome and ADHD trials were all in adults. Only the autism trials studied children. The largest one, Aran 2021, covered ages 5–21 and used one specific product with a 20:1 CBD-to-THC ratio. Its results cannot be applied to any other product.
What improved. In every trial, what improved was behaviour or symptoms, not the condition itself. Cannabinoids do not treat autism, ADHD or Tourette syndrome.
The developing brain. No study is long enough to answer the question families most need answered: “Is this safe for my child in the long run?” The honest answer is that nobody knows.
Blinding. When a product has effects people can feel, participants can guess they got the real thing. That weakens a double-blind design. In the 2023 Tourette pilot by Abi-Jaoude and colleagues, most of the 12 adults could tell whether they had received cannabis. This matters most in trials where parents or carers report the results.
Before you trust or share a study on this subject, check five things. How long was the treatment? How old were the participants? What exactly improved? Was there any long-term follow-up? Could participants tell what they got? Write the answers next to the link when you post it, so other readers can judge the study too.
6. Why This Subject Needs Care, Not Silence
Families who look into this are usually not doing it lightly. Many are dealing with severe self-injury or aggression, or a child whose distress dominates the home. Most have already tried standard options.
Existing treatments have serious side effects too. This is especially true of antipsychotics used for severe behaviour problems. Antipsychotics are strong medicines first developed for psychosis. Campaigners are right to point this out.
Brushing these families off is not neutral. Encouraging them with only the positive results is not neutral either.
The position that holds up is narrow. Any use is a specialist decision, made inside a specialist service, for one specific child. It needs a defined target symptom, a fixed trial period, an agreed rule for when to stop, and monitoring. It should not start from a forum post. Nobody should get a product for a child without a prescription.
If a family asks you for help, point them to a specialist service. Share those four points (target symptom, trial period, stopping rule, monitoring) as questions they can ask the specialist. Do not supply or recommend a product.
7. The Rules and the Health System in Thailand
Translator’s note: this section covers Thai law and practical steps in Thailand.
- Flower is a controlled herb. Cannabis flower is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568. The Notification was issued under the Thai Traditional Medicine Protection Act B.E. 2542 (1999) and has been in force since 26 June 2025.
- Prescription only. Flower may be sold only against a PT 33 prescription from an authorised practitioner. Each prescription covers at most 30 days.
- No advertising or online sales. Advertising flower and selling it online are both prohibited. Flower offered to you online or through advertising is being sold illegally.
- Two 2026 regulations tightened licensing. You can read about both in Thailand’s Two Ministerial Regulations of B.E. 2569. The Ministerial Regulation on Cannabis or Hemp Extracts B.E. 2569 has been in force since 26 April 2026. Licences for extracts with more than 0.2% THC go only to three kinds of holder: Thai juristic persons that are not “foreign” under the Foreign Business Act B.E. 2542, state agencies, and the Thai Red Cross Society. The Ministerial Regulation on Controlled Herbs (No. 2) B.E. 2569 has been in force since 30 April 2026 and tightens licence criteria for flower.
- The new Act is still a draft. The draft Cannabis Control Act was approved by Cabinet on 22 September 2026 and sent to the House. It is not law yet. Press reports say it would add an explicit ban on sales to persons under 20.
- The child’s best interests. Where a child is involved, every decision should put the child’s best interests first, and that includes any decision about cannabis.
Translator’s note: growers on this forum may be asked by a relative or neighbour for flower or homemade oil for a child. Under Section 78 of the 1999 Act, selling a controlled herb without a licence carries up to 1 year in prison, a fine of up to 20,000 baht, or both. A homemade oil also has no laboratory figure for its THC content, and no trial above tested anything like it. Say no, and send the family back to the child’s doctor.
Translator’s note: if you are a parent in Thailand, start with your child’s own doctor. Ask for a referral to a child psychiatrist or paediatric neurologist. Before the appointment, keep a written log of the main symptom for two weeks: how often it happens, how severe it is, and what sets it off. This gives the specialist a starting point to judge any change against.
A request for this thread
Please do not post stories about individual children in this thread. Here is what would help instead.
If you are a clinician in Thailand or elsewhere in the region and you work with these conditions, describe how referral actually works when a family raises cannabis. Is there a specialist to refer to, and what happens next? That is a question about the health system, not about any child. Your answer can help other families find the right service.
This article is part of the Asiannabis Community educational series on medical cannabis. It is general information, not medical advice. It is not a recommendation to use cannabis in children. The long-term effects of cannabinoids on the developing brain are unknown.
References for Part 2
- Cooper and colleagues, 2017: pilot randomised placebo-controlled trial of nabiximols in 30 adults with ADHD. European Neuropsychopharmacology.
- Abi-Jaoude and colleagues. Cannabis and Cannabinoid Research, 2023.
- Aran and colleagues. Molecular Autism, 2021.
- Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568; Ministerial Regulation on Cannabis or Hemp Extracts B.E. 2569; Ministerial Regulation on Controlled Herbs (No. 2) B.E. 2569; Thai Traditional Medicine Protection Act B.E. 2542, Section 78.