What does the research say?
There is only one study in ADHD that compared cannabinoids with a dummy treatment (placebo) with participants assigned to groups at random. In this study, done in England in 2014–2015, 30 adults with ADHD used either a prescription mouth spray containing roughly equal amounts of THC and CBD (nabiximols) or a placebo for 6 weeks. On the main measure, a computerized attention and activity test, there was no clear difference between the two groups. The spray group showed signs of improvement in hyperactivity and impulsivity and on a test of impulse control; however, once the large number of measurements was taken into account, these differences were no longer statistically significant. The researchers interpreted the results as preliminary findings, not firm ones. In studies of people with a tic disorder (Tourette syndrome), ADHD was examined only as a co-occurring condition and with THC-containing products: in a controlled study with 97 adults, the reduction in tics looked larger in those with ADHD, but the difference was not statistically significant; in a study with 10 teens and no comparison group, the drop in ADHD scores was also not significant (details on the site's Tourette Syndrome page).
The two most recent large reviews pooling cannabinoid studies in mental health conditions paint a similar picture for ADHD. In a 2026 review combining 54 studies across all mental health conditions in which participants were assigned to groups at random, there were not enough studies to run a pooled analysis for ADHD. In the other 2026 review, which examined 200 experimental and observational studies across all diagnoses, cannabinoids had a negligible or no effect on adult ADHD in randomized studies, and the certainty of the evidence was mostly very low. A review that screened 39 studies looking at cannabis in ADHD also wrote that most studies found cannabis either worsened ADHD symptoms or had no effect on them, that the amounts of THC and CBD in the products were often not measured, and concluded that, based on the current evidence, cannabis is not recommended for people with ADHD.
Studies without a comparison group look more positive, but they cannot separate the placebo effect from improvement that happens on its own over time. In a study in Israel with children and young people with autism and ADHD symptoms, 53 participants (about half of the 109 people enrolled) used a CBD-rich cannabis oil that also contains a small amount of THC (a CBD to THC ratio of 20 to 1 in the same center's autism program) for 3–6 months; in teacher ratings, hyperactivity-impulsivity and overall ADHD scores improved clearly, and attention scores less clearly; no clear relationship was seen between the dose used or blood CBD levels and improvement. In the UK medical cannabis registry, anxiety and sleep scores improved over 12 months in 68 adults prescribed it for ADHD; however, this registry did not measure ADHD symptoms themselves, most patients used inhaled cannabis flower, and the prescribed daily amount of THC was high (median about 209 mg); at month 12, only half of the patients took part in the assessment. The registry belongs to a private chain of clinics; 5 of the 6 authors have business ties to this chain or to the medical cannabis company that makes the most commonly prescribed products.
Many adults with ADHD say they use cannabis for their symptoms, but measurements show a more mixed picture. In a US survey answered by 900 adults diagnosed with ADHD, 75% of participants had used cannabis at least once, and 42% of them said they used cannabis for ADHD symptoms. Daily users, compared with occasional users, more often reported that cannabis reduced impulsivity and mental restlessness but worsened inattention; cannabis use disorder (addiction) was also more common in this group (62% versus 38%). In another study comparing 104 adults with and without ADHD, people with ADHD felt less impulsive after using their own cannabis and gave less impulsive responses on two tests; but their performance dropped on five other attention and memory measures. Regular users with ADHD reported milder mental sluggishness, yet they did worse on two objective tests.
Pure CBD or CBD oil has not yet been tested in any controlled study in ADHD. A study in Israel comparing a THC-free CBD oil with added terpenes against placebo in 120 children and teens aged 6–18 is registered; the record has not been updated since August 2024, and as of October 2026 it has no results. In the US and Brazil, two controlled studies with another cannabinoid called cannabigerol (CBG) are registered (in October 2026 both appear as 'recruiting' in the registries, with no results); the product in Brazil also contains CBD and a small amount of THC alongside CBG.
Cannabis use and cannabis use disorder are more common in teens and adults with ADHD. In a meta-analysis combining 14 studies, about 27% of people with ADHD had cannabis use disorder at some point in their lives, and this risk was about 2.9 times higher than in the general population. In another meta-analysis combining studies that followed people diagnosed with ADHD in childhood for years, children with ADHD were more likely to try cannabis later (odds ratio 2.8) and to develop cannabis abuse or dependence (2.3); co-occurring conduct problems complicate this relationship. In a study that followed 547 children diagnosed with ADHD at an average age of 8.5 up to age 25, weekly cannabis use in adulthood was 33% in those with ADHD and 21% in their classmates; daily use was 22% versus 11%. An analysis using genetic data suggested that the relationship may run more from a predisposition to ADHD toward cannabis use; it found no sign that cannabis use causes ADHD, but according to the authors the analysis testing that direction had limited power. These are observational studies; they do not prove cause and effect.
A review of 11 studies looking at the effects of cannabis on the brain and thinking skills of young people with ADHD found some differences in brain imaging; no study showed that cannabis caused additional harm to young people with ADHD on attention and planning tests; according to the authors, the small studies available do not support such harm, but they are not enough to rule it out either. In an exploratory analysis of one study, those who started cannabis before age 16 did worse on some tests; in another, early starters showed differences in brain structure. 5 of the 11 studies in the review were done with participants from the same long-term follow-up study. One of the studies in this review was from Turkey, done in adolescents aged 14–18 who used synthetic cannabinoids (chemicals that mimic the effect of THC and stimulate its receptors more strongly than THC). A 2026 review of 3 studies looking at the psychosis risk of cannabis in people with ADHD found very little evidence that this risk is additionally raised in people with ADHD; but both ADHD and cannabis use are separately known risk factors for psychosis.
The risks of THC in adolescence are not specific to ADHD, but they matter because cannabis use is more common in young people with ADHD. In a US study following more than 463,000 adolescents screened at ages 13–17, those who had used cannabis in the past year were about twice as likely to be diagnosed with a psychotic disorder later (observational). About one in five people who have used cannabis develop cannabis use disorder; in young people who use it weekly or daily, the risk of addiction rises to about one in three. In a controlled study in London with 24 adolescents aged 16–17 and 24 adults, inhaled THC impaired verbal memory and increased psychosis-like symptoms; adolescents were affected as much as adults, and adding CBD did not reduce these effects. According to a meta-analysis combining 69 studies, the decline in thinking skills in young people and adolescents who use cannabis frequently was small and was not clear after more than 72 hours of abstinence; in other words, some of the effects may be lingering effects of the most recent use.
The link between cannabis use in pregnancy and ADHD in the child has also been studied. In a meta-analysis combining 17 observational studies, a slight association was found after other factors were taken into account; in the largest study, which also measured use with a urine test and followed more than 141,000 children, no clear association was seen.
Strength of evidence: ○○○○ Insufficient evidence. Finding: Not studied enough. What does this mean?
Ongoing research on this topic
Trials testing CBD for this topic on ClinicalTrials.gov: 1 under way (1 recruiting). A trial being under way does not show that CBD works.
- NCT07592390: Phase 1/2, recruiting, target 60 participants
Possible side effects and drug interactions
In the only controlled study in ADHD, there was 1 serious side effect (muscle cramps and spasms) and 3 mild side effects in the THC and CBD spray group, and 1 serious side effect (cardiovascular problems) in the placebo group. In the UK registry, 11 of 68 patients reported a total of 61 side effects; the most common were insomnia, trouble concentrating, sleepiness, fatigue and dry mouth, and 16 were rated severe; there were no life-threatening side effects. Looking across all mental health condition studies, people taking cannabinoids were more likely than those on placebo to have any side effect (one extra side effect for every 7 people taking a cannabinoid, compared with placebo), with no difference in serious side effects; stopping the study because of side effects was more common in people taking THC.
People with ADHD often take medicines such as methylphenidate or atomoxetine. CBD can slow the breakdown of some medicines in the body; in healthy volunteers, high-dose CBD raised methylphenidate blood levels only slightly (by about 9% on average), and there are no human data with atomoxetine. In healthy volunteers, when THC and methylphenidate were taken together, their heart-rate-raising effects added up; in an old, small study, increases in heart rate and blood pressure also added up with cannabis smoked after dextroamphetamine. Both ADHD medicines and CBD can reduce appetite; weight and height are monitored in children. Details are below and on the site's ADHD medications page.
Interactions with medicines used for this condition
Interactions reported for these medicines in peer-reviewed publications and official prescribing information. A medicine that is not listed can still interact with CBD; tell your doctor about every medicine you take.
| Medicine | Importance | Warning | Source |
|---|---|---|---|
| Methylphenidate (Ritaline, Concerta, Medikinet) | Information | Methylphenidate: In healthy volunteers, 3 days of high-dose approved CBD (750 mg twice a day) raised the blood level of methylphenidate by about 9% on average; the researchers found this difference clinically unimportant. How large the effect is with long-term use, or with products containing THC, is not known. If you take an ADHD medicine, tell your doctor about CBD. | PMID 36467779, PMID 35512806 |
| Atomoxetine (Strattera, Attex, Atominex) | Information | Atomoxetine, vortioxetine: No human study has looked at these medicines and CBD together. CBD slowed the main enzyme that breaks down both of them (CYP2D6) in the lab; however, in a study in healthy volunteers, this enzyme's activity did not change. Tell your doctor about the medicines you take. | PMID 21821735, PMID 37313955, Atomoxetine prescribing information §12.3, dailymed.nlm.nih.gov, Vortioxetine prescribing information §12.3, dailymed.nlm.nih.gov |
To check interactions with the medicines you take: CBD drug interaction checker.
How was CBD used in studies?
In the only controlled study in ADHD, a mouth spray containing THC and CBD was used for 6 weeks; each spray contained 2.7 mg THC and 2.5 mg CBD; according to the tables of two reviews, the dose could go up to a maximum of 37.8 mg THC and 35 mg CBD a day (the study's own text could not be read; study dose, not a personal recommendation). In the UK registry, patients mostly used inhaled cannabis flower; the median prescribed daily amount was about 209 mg THC and 15 mg CBD (prescribed amount; not a personal recommendation). In the uncontrolled study with autistic children, the dose of the CBD-rich oil that also contains a small amount of THC is not stated in the abstract.
There is no dose of pure CBD or CBD oil that has been tested in ADHD studies. Because the results of the ongoing CBD oil study in children have not been released, the doses planned there are not given here.
Study details (for health professionals)
In the only randomized controlled trial of cannabinoids in ADHD (Cooper 2017; 30 adults, mouth spray containing THC and CBD, 6 weeks), there was no difference from placebo on the primary outcome (QbTest cognitive performance and activity) (estimate −0.17; 95% CI −0.40 to 0.07; p = 0.16); the improvement in hyperactivity-impulsivity (p = 0.03) and on an inhibition measure (p = 0.05) did not remain significant after correction for multiple testing. There are no controlled studies with pure CBD. In studies of Tourette syndrome and chronic tic disorder, ADHD was examined only as a co-occurring condition and with THC-containing products; these studies are in the table of the site's Tourette Syndrome page: in the 97-adult RCT (CANNA-TICS; mouth spray containing THC and CBD, 13 weeks), the reduction in tics looked larger versus placebo in those with ADHD but was not statistically significant (exploratory subgroup analysis; Müller-Vahl 2023, PMID 36878177; subgroup result Czech 2026, PMID 42123126), and the result of the ADHD symptom scale planned as a secondary outcome in the protocol appears neither in the article's abstract nor in the EU clinical trials register; in the uncontrolled study with 10 adolescents with Tourette syndrome (oil containing THC and CBD, 12 weeks), the parent-rated ADHD score fell from 32.8 to 25.4, but the change was not significant (p = 0.063; Eapen 2025, PMID 40636988). Uncontrolled data: in 53 children and young people with autism and ADHD symptoms, improvement in teacher ratings over 3–6 months with CBD-rich cannabis oil (Barchel 2026; the product in the same center's autism program was CBD:THC 20:1, meaning it contains a small amount of THC); in a manufacturer-supported, 12-week study in 14 children with pediatric acute-onset neuropsychiatric syndrome (PANS) using a CBDA-dominant extract with a small amount of THC, the ADHD symptom scale (Conners), one of the secondary measures, also improved (p = 0.028); all of the children had OCD symptoms and continued their other medicines (Keating 2026, PMID 41513541; the study is in the table of the site's OCD and Hair Pulling page); in the UK Medical Cannabis Registry, in 68 adults prescribed it for ADHD (mostly inhaled flower; median 209 mg THC and 15 mg CBD/day), improvement in anxiety and sleep scores up to 12 months and in quality of life up to 6 months; ADHD symptoms were not measured, 49% of patients were assessed at month 12, the registry belongs to a private chain of clinics, and 5 of the 6 authors have business ties to this chain or to the cannabis company that makes the most commonly prescribed products (Ittiphakorn 2023). A 2026 meta-analysis pooling cannabinoid RCTs in mental health conditions did not find enough data to run a pooled analysis for ADHD (Wilson 2026); a 2026 meta-analysis pooling experimental and observational studies reported that the effect in adult ADHD was negligible or absent, with certainty mostly very low (Bharat 2026); according to a 39-study scoping review, in most studies cannabis worsened ADHD symptoms or had no effect on them (Francisco 2023). Cannabis use in people with ADHD: lifetime prevalence of cannabis use disorder 26.9%, risk 2.85 times the general population (Froude 2024; 14 studies); childhood ADHD is associated with later cannabis use (OR 2.78; 95% CI 1.64–4.74) and with cannabis abuse or dependence (OR 2.29; 1.32–3.99) (Lee 2011); in the long-term follow-up of the multicenter MTA study, weekly use in adulthood was 32.8% versus 21.3% (Molina 2018); Mendelian randomization suggested a causal effect running from ADHD predisposition to cannabis use (OR 7.9; 95% CI 3.72–15.51) and found no effect in the reverse direction (Soler Artigas 2020); in a survey, 75% of adults with ADHD had used cannabis at least once, and use disorder was more common among daily users (62% versus 38%; Ryan 2026); under the influence of cannabis, impulsivity decreased in people with ADHD, but performance dropped on five cognitive measures (Stueber 2026); 31.3% of parents of children diagnosed with ADHD, autism or anxiety had given an unapproved CBD product (Schwaller 2023). In 11 studies looking at the effects of cannabis on the brain and cognition in young people with ADHD, no interacting harm of ADHD and cannabis was seen on executive function tests; early onset was associated with worse test results in one study (exploratory analysis) and with differences in brain structure in another; 5 of the 11 studies came from the same (MTA) cohort (Cawkwell 2021); there is little evidence that cannabis-related psychosis risk is additionally raised in people with ADHD (Suetani 2026; 3 studies). In adolescents (studies not specific to ADHD, and therefore not included in the table): cannabis use is associated with a later diagnosis of psychotic disorder (adjusted HR 2.19; Young-Wolff 2026, PMID 41719031), the risk of addiction in young people who use regularly is 33% (Leung 2020, PMID 32485547), inhaled THC also impaired memory in adolescents aged 16–17 and CBD did not reduce this (Lawn 2023, PMID 36750134), and cognitive decline in frequent users is small and not clear after more than 72 hours of abstinence (Scott 2018, PMID 29710074). Cannabis use in pregnancy is slightly associated with ADHD in the child (adjusted OR 1.13; Bassalov 2024); in the largest screened cohort there is no association (Young-Wolff 2025). October 2026 search (PubMed, Cochrane, ClinicalTrials.gov, Europe PMC): 1 controlled study of cannabinoids on this topic was found (mouth spray containing THC and CBD, 30 adults; Tourette studies that measured ADHD only as a co-occurring condition were not counted and are mentioned above); there are no controlled studies with pure CBD, no Cochrane review of cannabinoids in ADHD, and no registered unpublished studies with results. In addition, the table includes 2 uncontrolled studies, 3 reviews that also cover ADHD, 9 observational studies and reviews on cannabis use and its risks in people with ADHD, and 2 studies on cannabis use in pregnancy and ADHD in the child; all are in the table below. 4 sources on the risks of cannabis in adolescence that are not specific to ADHD are mentioned only in the text. There is one study that was stopped with 8 people because participants could not be found, with no results released; 3 controlled studies are ongoing or of unknown status (no results); no studies of cannabinoid treatment in ADHD from Turkey were found.
Evidence assessment: Pure CBD: Insufficient (no controlled studies with pure CBD or CBD oil in ADHD; in the only study without a comparison group, in autistic children, the CBD-rich oil used also contained a small amount of THC; a planned controlled study with THC-free CBD oil has no results)
CBD alone
There are no controlled studies of pure CBD or CBD oil in ADHD. In a study without a comparison group in children and young people with autism and ADHD symptoms, the CBD-rich oil also contained a small amount of THC (a CBD to THC ratio of 20 to 1 in the same center's autism program); so its result is in the THC-containing products section. A 120-person study in children and teens comparing a THC-free CBD oil with added terpenes against placebo is registered in Israel under a company's sponsorship; the record has not been updated since August 2024, and as of October 2026 it has no results.
Products containing THC
There is only one controlled study of THC-containing products in ADHD: in 30 adults over 6 weeks, a mouth spray containing THC and CBD was not clearly different from placebo on the main measure; the signs of improvement in hyperactivity and impulsivity did not survive correction for multiple comparisons. In 53 children and young people with autism and ADHD symptoms, improvement in teacher ratings over 3–6 months was reported with a CBD-rich oil that also contains a small amount of THC, but there was no comparison group. In a registry of 68 adults, most using inhaled cannabis, anxiety and sleep improved, but ADHD symptoms were not measured. In adults with ADHD using their own cannabis, impulsivity decreased somewhat, but performance dropped on many attention and memory tests. Two large reviews found insufficient evidence of benefit; according to a 39-study scoping review, in most studies cannabis worsened ADHD symptoms or had no effect on them. There are no controlled ADHD studies of THC-containing products in children and adolescents; cannabis use in adolescence is linked to risks of psychosis and addiction (observational).
Evidence: THC and THC+CBD: Very weak (a single small 6-week controlled study with 30 adults with ADHD, no difference on the main measure; other data come from uncontrolled studies (CBD-rich oil with a little THC in autistic children; UK patient registry), observational studies and surveys; no controlled studies in children and adolescents)
Dose range in studies
Nabiximols (mouth spray containing THC and CBD) at most 37.8 mg THC + 35 mg CBD/day, 6 weeks (the only controlled study; highest dose from review tables); in the UK registry the median prescribed amount was 209 mg THC + 15 mg CBD/day (mostly inhaled flower); no ADHD studies with pure CBD or CBD oil
Starting dose and titration
Not reported in detail in the studies.
These are doses researchers gave under medical supervision; they are not a recommended dose for you. "mg/kg/day" means milligrams per kilogram of body weight per day.
| Study | Participants | Product | Dose and titration | Duration | Result | Source |
|---|---|---|---|---|---|---|
| Cooper 2017 (EMA-C) Double-blind, placebo-controlled, parallel-group pilot RCT (single center, London) | 30 randomized (15 nabiximols / 15 placebo); 15 / 11 in the primary analysis Adults diagnosed with ADHD (ages 18–55; England) | Nabiximols (Sativex), oromucosal spray; each spray 2.7 mg THC + 2.5 mg CBD; placebo spray | Highest daily dose 37.8 mg THC + 35 mg CBD (secondary source: tables of the Bilbao 2022 and Cooling 2026 reviews; the full text of the study could not be read); the average dose used is not in the abstract Not reported (in the abstract; the full text could not be read) | 6 weeks | No difference from placebo on the primary outcome (QbTest: cognitive performance and activity measures) (estimate −0.17; 95% CI −0.40 to 0.07; p = 0.16). On secondary measures, nominal improvement in hyperactivity-impulsivity (p = 0.03) and on a cognitive inhibition (impulse control) measure (p = 0.05), with trends in inattention (p = 0.10) and emotional lability (p = 0.11); none significant after correction for multiple testing. Effects were larger in those who followed the protocol. The authors interpret the result as preliminary evidence, not a firm one Side effects: 1 serious (muscle cramps and spasms) and 3 mild side effects in the nabiximols group; 1 serious side effect (cardiovascular problems) in the placebo group | PMID 28576350, doi:10.1016/j.euroneuro.2017.05.005, NCT02249299, August 2014–June 2015, PMID 35982439, PMID 41343139, Table 2) |
| Wilson 2026 Systematic review and meta-analysis of RCTs (1980–May 13, 2025; PROSPERO CRD42023392718; GRADE) | 54 RCTs, 2,477 participants (all mental health conditions and substance use disorders); not enough studies in ADHD for a meta-analysis People with a mental health condition or substance use disorder (including ADHD) | Cannabinoids (CBD, THC, combinations of the two and other cannabinoids) | There were not enough data to run a meta-analysis for ADHD (abstract). Across all diagnoses, the certainty of the evidence is low for most outcomes; 44% of the studies have a high risk of bias. According to the authors, routine use of cannabinoids in mental health conditions can rarely be justified for now Side effects: The chance of any side effect was higher with cannabinoids (OR 1.75; 95% CI 1.25–2.46; number needed to harm 7); no difference in serious side effects or study withdrawal | PMID 41856154, doi:10.1016/S2215-0366(26)00015-5, Correction: Lancet Psychiatry 2026, PMID 42302809, June 16, 2026: the axis of a figure and the study counts in the table were corrected, results unchanged). The same review is also in the site's anxiety, psychosis, depression, bipolar, sleep, substance use, autism and Tourette syndrome tables | ||
| Bharat 2026 Systematic review and meta-analysis of experimental and observational studies (up to May 2025; PROSPERO CRD42023467536; GRADE) | 82 experimental and 118 observational studies (all diagnoses; the number of ADHD studies is not in the abstract) Adults (aged 18 and over) with ADHD, anxiety, depression, PTSD, psychosis, Tourette syndrome or substance use disorder | THC, CBD, combinations of the two and other cannabinoids; medical cannabis | In RCTs, cannabinoids had a negligible or no effect on ADHD (the numerical result and the number of studies it is based on are not in the abstract). Across all diagnoses, observational studies suggest improvement, but the risk of bias is high. The certainty of the evidence is mostly very low; the authors do not support cannabinoids as a first-line treatment. The full text could not be read Side effects: The only significant safety finding: stopping the study because of side effects was more common with THC (OR 2.78; 95% CI 1.66–4.65) | PMID 42617303, doi:10.1016/j.psychres.2026.117380, The same review is also in the site's Depression and Tourette Syndrome tables | ||
| Francisco 2023 Scoping review (systematic search: MEDLINE, EMBASE, EMCARE, PsycINFO, Web of Science, Cochrane, ClinicalTrials.gov; up to June 27, 2022) | 39 studies (1 RCT; most cross-sectional) People with ADHD (experimental and observational studies) | Cannabis and cannabinoid products (THC and CBD amounts not measured in most studies) | In the only study directly measuring the effect of cannabis against placebo in ADHD (Cooper 2017), no difference on the primary outcome. Most of the literature consists of cross-sectional studies looking at the relationship between ADHD severity and cannabis use; 15 studies used neuropsychological tests or brain imaging. Although some studies reported improvement, most showed that cannabis worsened ADHD symptoms or had no effect on them. According to the authors, cannabis is not recommended for people with ADHD based on the current evidence; there are no objective measures of cannabis exposure and symptoms, and samples are small | PMID 36508935, doi:10.1016/j.jpsychires.2022.11.029 | ||
| Barchel 2026 Prospective, single-arm, open-label study (single center; no control group) | 109 enrolled (November 2019–April 2021); 53 were rated by teachers before and after treatment Children and young adults with autism spectrum disorder and ADHD symptoms (Israel, Shamir Medical Center) | CBD-rich cannabis oil; ratio and product name not in the abstract. The same center's autism program in the same period (ClinicalTrials.gov NCT05212493; Hacohen 2022, Stolar 2022, Treves 2026) used whole-plant oils with a CBD:THC ratio of 20:1 | Not reported (in the abstract). In another publication from the same cohort (Treves 2026), the mean maximum CBD dose was 2.8–3.1 mg/kg/day Not reported (in the abstract) | 3–6 months | On the teacher-completed Conners scale, significant improvement in anxious-shy, perfectionism, ADHD index, emotional lability and hyperactivity-impulsivity (p < 0.001); a trend toward improvement in oppositional behavior, cognitive inattention, hyperactivity, global index and DSM-IV inattention scores (p = 0.003–0.009). Dose or blood cannabinoid levels were not associated with improvement (only for emotional lability did higher CBD levels predict more improvement). Of the 109 people enrolled, 53 (about half) were assessed with the teacher scale before and after treatment. No control group; the placebo effect and improvement over time cannot be separated. The article's funding and conflict-of-interest statements could not be read; the program's registry record lists two medical cannabis companies (Seach Sarid, Canndoc) as collaborators Side effects: Not reported (in the abstract) | PMID 41503912, doi:10.2174/011570159X390368251014072051, In the PubMed and Crossref records, first name and surname are swapped (first author Dana Barchel, 'Dana B' in PubMed). The same cohort (Shamir Medical Center, November 2019–April 2021, NCT05212493, 2019, two CBD:THC 20:1 oils) and Hacohen 2022, Stolar 2022, Treves 2026 in the site's Autism table |
| Ittiphakorn 2023 (UK Medical Cannabis Registry) Uncontrolled case series (prospective patient registry; months 1, 3, 6 and 12) | 68 (33 people assessed at month 12) Adults whose primary reason for a medical cannabis prescription was ADHD (England; mean age 35.6; 81% male; 81% were already using cannabis when they started) | Prescription cannabis products: inhaled dried flower only 56%, sublingual oil only 6%, both 38% (most commonly prescribed flower: Adven EMT1) | Median prescribed daily THC 208.75 mg (IQR 120.6–291.4), CBD 15 mg (5.1–55.0); in the 4 patients using oil only, median 5 mg THC + 17.5 mg CBD Not reported | 12 months | Anxiety (GAD-7: from 10.85 to 8.44 at month 12) and sleep quality scores improved from baseline at months 1, 3, 6 and 12; overall quality of life (EQ-5D-5L) improved at months 1, 3 and 6, with no difference at month 12. ADHD symptoms were not measured separately; 49% of patients (33/68) were assessed at month 12. Over 12 months, 5 of 13 people taking lisdexamfetamine and 3 of 20 taking methylphenidate stopped their medicine; during the same period 3 people newly started methylphenidate and 2 started dexamfetamine. Missing data were filled with baseline values; no control group, and according to the authors causality cannot be established. The registry belongs to a private chain of clinics (Sapphire Medical Clinics); 5 of the 6 authors have company ties: three work at this chain (head of research, chief clinical pharmacist, director of operations), one is a former director of the chain, and the senior author is chief medical officer of Curaleaf International, the maker of the most commonly prescribed products (Adven); no external funding Side effects: 11 of 68 patients (16.2%) reported a total of 61 side effects (19 mild, 26 moderate, 16 severe); most common were insomnia, trouble concentrating, sleepiness, fatigue and dry mouth (5 each); no life-threatening or disabling side effects | PMID 38058251, doi:10.1002/npr2.12400, PMC10739081 (full text) |
| Froude 2024 Systematic review and meta-analysis (PubMed, PsycINFO, Web of Science) | 14 studies People with ADHD (clinical and community samples) | Cannabis (diagnosis of cannabis use disorder) | Not applicable | In people with ADHD, the lifetime prevalence of cannabis use disorder was 26.9% and the current prevalence 19.2% (wide prediction intervals: 12.4–48.8% and 5.5–39.1%). The risk of lifetime and current cannabis use disorder in people with ADHD was 2.85 and 2.91 times that of the general population. The authors recommend screening for cannabis use disorder as part of ADHD care. Observational data Side effects: Not applicable (observational) | PMID 38452637, doi:10.1016/j.jpsychires.2024.02.050 | |
| Lee 2011 Meta-analysis of prospective follow-up studies | 27 studies (cannabis trial use: 7 studies, 600 with ADHD and 2,661 comparison; cannabis use disorder: 943 with ADHD and 1,885 comparison) People with and without an ADHD diagnosis in childhood | Cannabis (later use and use disorder) | Not applicable | From childhood to adolescence or adulthood (mean age at follow-up 18.9) | People with childhood ADHD were more likely to later use cannabis at least once (OR 2.78; 95% CI 1.64–4.74; marked heterogeneity between studies) and more likely to develop cannabis abuse or dependence (OR 2.29; 95% CI 1.32–3.99). No sign of publication bias. Co-occurring conduct disorder makes it hard to isolate the effect of ADHD itself. Observational data Side effects: Not applicable (observational) | PMID 21382538, doi:10.1016/j.cpr.2011.01.006, PMC3180912 (author manuscript) |
| Molina 2018 (MTA follow-up) Prospective multicenter cohort (observational long-term follow-up of a treatment RCT; comparison: children without ADHD from the same classrooms) | 547 children with ADHD and 258 classmates People diagnosed with combined-type ADHD in childhood (at a mean age of 8.5) | Cannabis (self-report, confidential questionnaire) | Not applicable | From a mean age of 10 to age 25 (up to 8 assessments) | Weekly cannabis use in adulthood was 32.8% in the ADHD group and 21.3% in the comparison group; daily use 22% versus 11%. More people in the ADHD group started substance use (alcohol, tobacco, cannabis) early in adolescence; early onset predicted heavier use in adulthood in both groups. Observational data Side effects: Not applicable (observational) | PMID 29315559, doi:10.1111/jcpp.12855, PMC5985671 (author manuscript). Correction: J Child Psychol Psychiatry 2018, PMID 30339284, content could not be read). The share of early starters in adolescence is 57.9% versus 41.9% in the abstract and 57.6% versus 40.3% in the author manuscript |
| Soler Artigas 2020 Genetic study: genetic correlation and bidirectional, two-sample Mendelian randomization using genome-wide association data | 53,293 people for ADHD; 32,330 people for lifetime cannabis use (summary statistics) Summary data from large genetic studies (ADHD and cannabis use) | Cannabis (lifetime use) | Not applicable | Genetic correlation between ADHD and cannabis use (rg = 0.29). Mendelian randomization suggested a causal effect of ADHD predisposition increasing cannabis use (estimated OR 7.9 for having ADHD; 95% CI 3.72–15.51); no effect was found in the reverse direction (from cannabis use to ADHD), but the authors note that this analysis may have had low power. Mendelian randomization relies on assumptions that are hard to verify Side effects: Not applicable | PMID 30610198, doi:10.1038/s41380-018-0339-3, PMC8025199 (author manuscript). Correction: Mol Psychiatry 2021, PMID 33627840, content could not be read) | |
| Suetani 2026 Systematic review (synthesis without meta-analysis, SWiM) | 3 studies People with ADHD who use cannabis (psychosis outcomes) | Cannabis | Not applicable | Only 3 studies meeting the criteria were found (with different designs; one of moderate and two of good quality). Two indirectly suggested that cannabis use does not additionally affect psychosis risk in people with ADHD, and one that cannabis affects psychosis risk similarly in people with and without ADHD. According to the authors, there is very little evidence that cannabis-related psychosis risk is higher in people with ADHD; ADHD and cannabis use are separately known risk factors for psychosis. The full text could not be read Side effects: Not applicable | PMID 41916924, doi:10.1177/10398562261439662 | |
| Cawkwell 2021 Systematic review (PRISMA; PubMed, Embase, PsycINFO, Cochrane CENTRAL; up to January 1, 2020) | 11 studies (7 brain imaging) Adolescents and young adults with ADHD (under 25); users and non-users of cannabis or synthetic cannabinoids | Cannabis (10 studies) and synthetic cannabinoids (1 study, Turkey) | Not applicable | Imaging studies found differences in activity and structure in some brain regions in young people with ADHD who use cannabis; no study showed an additive or interacting harm of ADHD and cannabis on executive function tests. According to the authors, the limited and possibly underpowered evidence does not support the hypothesis that cannabis impairs neuropsychological test performance in young people with ADHD. Starting cannabis early was associated with negative differences in two studies: in an exploratory analysis of one, those who started before age 16 did worse on decision-making, working memory and impulsive error tests; in the other, there were differences in brain structure. 5 of the 11 studies (all three fMRI studies) were done with participants from the same cohort (MTA follow-up); the evidence is limited and the studies small, and the authors call for larger and longer studies. One of the studies was done in Turkey in adolescents aged 14–18 who used synthetic cannabinoids Side effects: Not applicable | PMID 34138796, doi:10.1097/HRP.0000000000000303, PMID 31523140 | |
| Stueber 2026 Quasi-experimental, repeated-measures observational study (two sessions; users used their own products under observation in the second session) | 104 adults (26 per group: cannabis users and non-users, with and without ADHD) Adults with and without ADHD (US) | Participants' own cannabis products (THC and CBD amounts not in the abstract) | Amount chosen by the participant (not in the abstract) | Two sessions | Regular cannabis users with ADHD reported milder mental sluggishness than non-users with ADHD, but did worse on two objective cognitive tests (like users without ADHD). People with ADHD under the influence of cannabis reported reduced impulsivity, irritability and anxiety and improved mood, and gave less impulsive responses on two tests; but their performance dropped on five other cognitive measures. Not randomized; products differed from person to person. 1 of 4 authors (the senior author) declares receiving materials, outside the study, from a vaporizer manufacturer (Storz & Bickel) and research funding from four companies (Huxley Health, Healer, CReDO Science, Terra Mater Botanicals); the study was supported by the university's alcohol-substance and cannabis research funds Side effects: Drop in performance on five cognitive measures under the influence of cannabis | PMID 41062851, doi:10.1007/s00213-025-06921-9 |
| Ryan 2026 Cross-sectional online survey (single health system; self-report) | Sent to 9,274 people, 900 responses Adults with an ADHD diagnosis in their health records (US) | Cannabis (self-report) | Not applicable | April–July 2023 | 75% of participants had used cannabis at least once and 41% in the past 30 days; 42% of those who had ever used it (278 people) said they used cannabis for ADHD symptoms. Among daily users, cannabis use disorder (62% versus 38%; OR 2.67; 95% CI 1.69–4.22) and diagnoses of anxiety, depression, bipolar disorder and PTSD were more common than among occasional users. Daily users more often reported that cannabis reduced mental restlessness and impulsivity but worsened inattention. Low response rate (about 10%), self-report; does not show cause and effect Side effects: Not applicable (survey) | PMID 40874736, doi:10.1177/10870547251364575 |
| Schwaller 2023 Cross-sectional online survey (nationwide parent panel) | 518 parents Parents of children aged 7–18 diagnosed with ADHD, autism or generalized anxiety disorder (US) | Unapproved CBD products (contents and THC amount unknown) | Not applicable | 31.3% of parents (162 people) had given their child an unapproved CBD product; use was most common in children with generalized anxiety disorder or multiple diagnoses and in the western US. Parents who gave CBD had more positive views about the safety of these products. The rate for children with ADHD alone is not in the abstract; the survey does not measure effectiveness Side effects: Not applicable (survey) | PMID 37795288, doi:10.5863/1551-6776-28.4.323 | |
| Bassalov 2024 Systematic review and meta-analysis of observational studies (up to January 22, 2024; PRISMA, MOOSE) | 18 studies (17 in the meta-analysis), 534,445 participants Children of mothers who did and did not use cannabis in pregnancy | Cannabis (medical or recreational; any route and trimester) | Not applicable | After accounting for confounding factors, cannabis use in pregnancy was slightly associated with ADHD in the child (OR 1.13; 95% CI 1.01–1.26); associations with autism, psychotic symptoms, anxiety and depression were not clear; it was associated with the child's later cannabis use (OR 1.20; 1.01–1.42). Observational data Side effects: Not applicable (observational) | PMID 38908654, doi:10.1016/j.ajog.2024.06.014 | |
| Young-Wolff 2025 Retrospective birth cohort (Kaiser Permanente Northern California; universal screening at about weeks 8–10 of pregnancy: self-report and urine test) | 141,570 children (117,130 pregnant women) Children of mothers screened for cannabis use in pregnancy (US) | Cannabis (self-report or urine test) | Not applicable | Up to age 11 (born 2011–2018) | Cannabis use was detected in 4.6% of pregnant women. After accounting for other substance use and sociodemographic factors, cannabis use in pregnancy was not associated with an ADHD diagnosis in the child (adjusted HR 0.84; 95% CI 0.70–1.01); there was an inverse association with disruptive behavior disorders (0.83; 0.71–0.97); frequency of use was not associated with the outcome. Observational data Side effects: Not applicable (observational) | PMID 39400201, doi:10.1097/DBP.0000000000001323, PMC11832326 |
Reported side effects
- Nabiximols, 6 weeks: 1 serious side effect (muscle cramps and spasms) and 3 mild side effects in the spray group; 1 serious side effect (cardiovascular problems) in the placebo group (Cooper 2017)
- UK registry, 12 months: 11 of 68 patients reported 61 side effects (16 severe); most common were insomnia, trouble concentrating, sleepiness, fatigue and dry mouth; no life-threatening side effects (Ittiphakorn 2023)
- Under the influence of cannabis, a drop in performance on five cognitive measures in adults with and without ADHD (Stueber 2026)
- Inhaled THC and THC + CBD impaired verbal memory and increased psychosis-like symptoms in adolescents aged 16–17 and in adults; adding CBD did not reduce this (healthy volunteers who use cannabis; Lawn 2023, PMID 36750134)
- Across all mental health condition RCTs, the chance of any side effect rose with cannabinoids (OR 1.75; number needed to harm 7), with no difference in serious side effects (Wilson 2026); stopping because of side effects was more common with THC (OR 2.78; Bharat 2026)
Monitoring done in studies
- Screening for cannabis use disorder and co-occurring mental health diagnoses is recommended in people with ADHD who use cannabis (Froude 2024; Ryan 2026)
- Because both ADHD medicines and CBD can reduce appetite, weight and height are monitored by a doctor in children; details are on the site's ADHD medications page (methylphenidate and atomoxetine product information, product information for approved CBD)
- Ongoing studies (October 2026): in Israel, THC-free CBD oil with added terpenes versus placebo in 120 children and teens aged 6–18 (NCT06542445; according to the record it started in August 2024, estimated completion September 2026; the record has not been updated since August 2024 and its status is 'unknown'); in the US, a single 80 mg dose of cannabigerol (CBG) versus placebo in 76 adults aged 18–55, with attention and memory tests (NCT06115603; the record was last updated in May 2026 and appears as 'recruiting'; planned completion was July 2026); in Brazil, a full-spectrum oil containing CBG, CBD and THC versus placebo in 60 young people aged 12–17, 12 weeks (NCT07592390; recruiting, estimated completion December 2026). None has results yet
Who should be careful
- The only controlled study in ADHD was done with a THC-containing spray and showed no benefit on the main measure; CBD oils have never been tested in a controlled study in ADHD (Cooper 2017)
- Children and adolescents: there are no controlled ADHD studies of cannabinoids in children; in observational studies not specific to ADHD, cannabis use in adolescence was linked to a later diagnosis of psychotic disorder (adjusted HR 2.19; Young-Wolff 2026, PMID 41719031), and about one in three young people who used it regularly developed addiction (Leung 2020, PMID 32485547)
- People with ADHD: cannabis use disorder is more common (lifetime about 27%, about 2.9 times the general population; Froude 2024); in an exploratory analysis of one study, those who started cannabis before age 16 did worse on some thinking tests; according to a review, however, it has not been shown that cannabis additionally impairs test performance in young people with ADHD, and the evidence is limited (Cawkwell 2021)
- Personal or family history of psychosis: in a controlled study with healthy adolescents and adults who use cannabis, THC increased psychosis-like symptoms and adding CBD did not prevent this (Lawn 2023, PMID 36750134); there is little evidence that this risk is additionally raised in people with ADHD (Suetani 2026). A person with a history of psychosis should not use cannabis products without consulting a doctor (this is a precautionary recommendation, not a direct study finding)
- Pregnancy: cannabis use in pregnancy was slightly associated with ADHD in the child (adjusted OR 1.13; Bassalov 2024), while no association was seen in the largest cohort (Young-Wolff 2025); the safety of CBD in pregnancy was not examined in these studies
- Schoolwork and tasks that need attention: under the influence of cannabis, performance dropped on five attention and memory measures (Stueber 2026); inhaled THC also impaired verbal memory in adolescents (Lawn 2023, PMID 36750134)
- Unapproved CBD products: in a US survey, 31% of parents of children diagnosed with ADHD, autism or anxiety had given their child an unapproved CBD product; the survey did not measure the products' contents or THC amounts (Schwaller 2023)
Drug interactions
- Detailed information and monitoring recommendations are on the 'ADHD medications' page in the site's drug interactions section (methylphenidate and atomoxetine)
- Methylphenidate: in 12 healthy volunteers, 750 mg of approved CBD twice a day for 3 days raised the total blood exposure of a single 10 mg dose of methylphenidate by 9% on average (geometric mean ratio 1.09; 90% CI 0.89–1.32); the researchers considered this clinically insignificant (Markowitz 2022, PMID 36467779). Laboratory and modeling studies predict a larger increase with repeated high CBD doses; this has not been confirmed in humans (Qian 2022, PMID 35512806)
- Atomoxetine: no human studies have examined it together with CBD; CBD slowed CYP2D6, the enzyme that breaks down atomoxetine, in the laboratory, but a CBD-dominant cannabis extract did not slow it in healthy volunteers (PMID 21821735; PMID 37313955)
- THC and methylphenidate: in 16 volunteers without mental illness who used cannabis occasionally, increases in heart rate added up when 10 mg of oral THC was taken together with 10 or 40 mg of methylphenidate (peak heart rate averaged 89, 96 and 102 beats/min when 0, 10 and 40 mg of methylphenidate were added to THC); THC increased the number of errors on an attention test (Kollins 2015, PMID 25175495)
- No human studies were found examining CBD with amphetamine derivatives (lisdexamfetamine, dexamfetamine), guanfacine or clonidine (October 2026 search). There are a few small laboratory studies with THC: in volunteers, cannabis smoked after 10 mg of dextroamphetamine added to the increases in heart rate and blood pressure (Evans 1976, PMID 782773); in volunteers who used cannabis regularly, guanfacine (2–3 mg a day) was well tolerated together with smoked cannabis or 20 mg of oral THC, a small drop in blood pressure was seen, and THC's heart-rate-raising effect did not change (Haney 2019, PMID 29659126; Mathai 2018, PMID 28641496); in a 15-patient open-label study testing atomoxetine together with dronabinol (synthetic THC) for sleep apnea, side effects were common and one third of patients stopped treatment (Messineo 2023, PMID 36805833)
- In the UK registry, over 12 months, 5 of 13 people taking lisdexamfetamine and 3 of 20 taking methylphenidate stopped their medicine; during the same period 3 people newly started methylphenidate and 2 started dexamfetamine (Ittiphakorn 2023); this is an uncontrolled observation, not evidence of benefit or of an interaction
Abbreviations: RCT, randomized controlled trial (a study in which participants are assigned to groups by chance); placebo, an inactive substance; SMD, OR and RR, effect measures used in analyses that pool studies; CYP, liver enzymes that break down medicines.
If you are considering CBD
- You can discuss the established treatments for ADHD (medicines and behavioral approaches) with your child psychiatrist or psychiatrist; CBD has not been shown to replace them.
- Do not stop your ADHD medicine or change its dose on your own; if you are thinking about using CBD, tell your doctor and pharmacist.
- If you are thinking about giving a CBD product to your child or teen, talk to the doctor who follows them first; check the label and an independent certificate of analysis to see whether the product contains THC.
- In adolescence, THC-containing products call for extra caution because of addiction, psychosis and attention and memory problems; tell your doctor if there is a personal or family history of psychosis.
- If you are a teen or adult with ADHD who uses cannabis, it may help to talk openly with your doctor about how often you use it; researchers recommend screening for cannabis use disorder as part of ADHD care.
Choose your age group, medicines and situation to prepare a short summary you can take to your doctor. Nothing you enter is sent anywhere.
Bottom line
CBD oil has not yet been tested in a controlled study in ADHD; the only small controlled study, with a THC-containing spray, also showed no clear benefit. Because cannabis use and addiction are more common in young people with ADHD, THC-containing products call for caution, especially in adolescence. ADHD has established treatments; talking with the doctor who follows you or your child before trying anything new is the safest path.
Frequently asked questions
Does CBD oil work for ADHD?
There is not yet enough research to know. Pure CBD or CBD oil has never been compared with placebo in ADHD. In the only controlled study, with 30 people, which tested a mouth spray containing THC and CBD, there was no clear difference on the main measure. A study in children with autism and ADHD symptoms using an oil that is CBD-rich but also contains a small amount of THC reported improvement, but it had no comparison group. So the evidence for CBD is insufficient.
Does cannabis help with focus?
Many adults with ADHD say they use cannabis for their symptoms, but measurements show a different picture. Adults with ADHD tested after using their own cannabis felt less impulsive and gave less impulsive responses on two tests; but their performance dropped on five other attention and memory measures. Adults with ADHD who used it daily more often reported that their inattention got worse. According to a review that screened 39 studies, in most studies cannabis worsened ADHD symptoms or had no effect on them; the strength of evidence is very weak.
Can I give my child CBD oil for ADHD?
There are no controlled studies of CBD or other cannabinoids for ADHD in children and adolescents; long-term safety is also unknown. A study in Israel comparing a THC-free CBD oil with added terpenes against placebo in children and teens is registered; the record has not been updated since 2024, and as of October 2026 it has no results. CBD can slow the breakdown of some medicines in the body, and both ADHD medicines and CBD can reduce appetite; THC-containing products, for their part, are linked to risks of addiction and psychosis in adolescence. The decision should be made together with the child psychiatrist who follows your child.
What can happen if teens with ADHD use cannabis?
Cannabis use and addiction are more common in young people with ADHD: about 27% of people with ADHD had cannabis use disorder at some point in their lives; people diagnosed with ADHD in childhood more often used cannabis weekly in adulthood (33% versus 21%). In one study, those who started cannabis before age 16 did worse on some thinking tests; but according to a review that combined studies, it has not been shown that cannabis additionally impairs the test performance of young people with ADHD (the evidence is limited and the studies small). In general, cannabis use in adolescence is linked to an increased risk of psychosis; there is little evidence that this risk is additionally raised in people with ADHD. These are observational studies; they do not prove that cannabis causes these problems, but they are reason enough to be careful.
Does CBD interact with ADHD medicines?
Methylphenidate: in healthy volunteers, 3 days of high-dose approved CBD raised methylphenidate blood levels by about 9% on average; the researchers considered this clinically insignificant. Atomoxetine: no human studies. No studies were found examining CBD with amphetamine derivatives such as lisdexamfetamine, or with guanfacine. In healthy volunteers, when THC and methylphenidate were taken together, their effects on heart rate added up; in an old, small study, the effects on heart rate and blood pressure of cannabis smoked with dextroamphetamine also added up. If you use CBD, tell your doctor and pharmacist; details are on the site's ADHD medications page.
Does using cannabis during pregnancy cause ADHD in the child?
No study says this for certain. In a meta-analysis combining 17 observational studies, after other factors were taken into account, ADHD was slightly more common in children of mothers who used cannabis during pregnancy (odds ratio 1.13); in the largest study, which followed more than 141,000 children and also measured use with a urine test, no clear association was seen. The safety of CBD in pregnancy was not examined in these studies; if you are pregnant or planning a pregnancy, talk to your doctor about cannabis products.
Can CBD oil be obtained with a prescription for ADHD in Turkey?
In Turkey, products derived from cannabis are regulated by the Kenevirden Elde Edilen Ürünlere Dair Yönetmelik (Regulation on Products Derived from Hemp) dated January 31, 2026. These products, including CBD, may be sold only in pharmacies. Those classed as medicines or health products are dispensed with a prescription; the regulation does not state a prescription requirement for supplement products and cosmetics with a THC content of at most 0.3%. As of October 2026, there is no approved (licensed) CBD medicine in Turkey. If you are considering using it, talk to your doctor first.
References
Show 17 references
- Cooper 2017 (EMA-C). Double-blind, placebo-controlled, parallel-group pilot RCT (single center, London). PMID 28576350, doi:10.1016/j.euroneuro.2017.05.005, NCT02249299, August 2014–June 2015, PMID 35982439, PMID 41343139, Table 2)
- Wilson 2026. Systematic review and meta-analysis of RCTs (1980–May 13, 2025; PROSPERO CRD42023392718; GRADE). PMID 41856154, doi:10.1016/S2215-0366(26)00015-5, Correction: Lancet Psychiatry 2026, PMID 42302809, June 16, 2026: the axis of a figure and the study counts in the table were corrected, results unchanged). The same review is also in the site's anxiety, psychosis, depression, bipolar, sleep, substance use, autism and Tourette syndrome tables
- Bharat 2026. Systematic review and meta-analysis of experimental and observational studies (up to May 2025; PROSPERO CRD42023467536; GRADE). PMID 42617303, doi:10.1016/j.psychres.2026.117380, The same review is also in the site's Depression and Tourette Syndrome tables
- Francisco 2023. Scoping review (systematic search: MEDLINE, EMBASE, EMCARE, PsycINFO, Web of Science, Cochrane, ClinicalTrials.gov; up to June 27, 2022). PMID 36508935, doi:10.1016/j.jpsychires.2022.11.029
- Barchel 2026. Prospective, single-arm, open-label study (single center; no control group). PMID 41503912, doi:10.2174/011570159X390368251014072051, In the PubMed and Crossref records, first name and surname are swapped (first author Dana Barchel, 'Dana B' in PubMed). The same cohort (Shamir Medical Center, November 2019–April 2021, NCT05212493, 2019, two CBD:THC 20:1 oils) and Hacohen 2022, Stolar 2022, Treves 2026 in the site's Autism table
- Ittiphakorn 2023 (UK Medical Cannabis Registry). Uncontrolled case series (prospective patient registry; months 1, 3, 6 and 12). PMID 38058251, doi:10.1002/npr2.12400, PMC10739081 (full text)
- Froude 2024. Systematic review and meta-analysis (PubMed, PsycINFO, Web of Science). PMID 38452637, doi:10.1016/j.jpsychires.2024.02.050
- Lee 2011. Meta-analysis of prospective follow-up studies. PMID 21382538, doi:10.1016/j.cpr.2011.01.006, PMC3180912 (author manuscript)
- Molina 2018 (MTA follow-up). Prospective multicenter cohort (observational long-term follow-up of a treatment RCT; comparison: children without ADHD from the same classrooms). PMID 29315559, doi:10.1111/jcpp.12855, PMC5985671 (author manuscript). Correction: J Child Psychol Psychiatry 2018, PMID 30339284, content could not be read). The share of early starters in adolescence is 57.9% versus 41.9% in the abstract and 57.6% versus 40.3% in the author manuscript
- Soler Artigas 2020. Genetic study: genetic correlation and bidirectional, two-sample Mendelian randomization using genome-wide association data. PMID 30610198, doi:10.1038/s41380-018-0339-3, PMC8025199 (author manuscript). Correction: Mol Psychiatry 2021, PMID 33627840, content could not be read)
- Suetani 2026. Systematic review (synthesis without meta-analysis, SWiM). PMID 41916924, doi:10.1177/10398562261439662
- Cawkwell 2021. Systematic review (PRISMA; PubMed, Embase, PsycINFO, Cochrane CENTRAL; up to January 1, 2020). PMID 34138796, doi:10.1097/HRP.0000000000000303, PMID 31523140
- Stueber 2026. Quasi-experimental, repeated-measures observational study (two sessions; users used their own products under observation in the second session). PMID 41062851, doi:10.1007/s00213-025-06921-9
- Ryan 2026. Cross-sectional online survey (single health system; self-report). PMID 40874736, doi:10.1177/10870547251364575
- Schwaller 2023. Cross-sectional online survey (nationwide parent panel). PMID 37795288, doi:10.5863/1551-6776-28.4.323
- Bassalov 2024. Systematic review and meta-analysis of observational studies (up to January 22, 2024; PRISMA, MOOSE). PMID 38908654, doi:10.1016/j.ajog.2024.06.014
- Young-Wolff 2025. Retrospective birth cohort (Kaiser Permanente Northern California; universal screening at about weeks 8–10 of pregnancy: self-report and urine test). PMID 39400201, doi:10.1097/DBP.0000000000001323, PMC11832326
Points that could not be verified from the full text
- The full text of the only controlled study (Cooper 2017) is not open access: the highest daily dose (37.8 mg THC + 35 mg CBD) was taken from the tables of two reviews dated 2022 and 2026, and the age range and duration from the ClinicalTrials.gov record (NCT02249299); how the dose was adjusted, the average dose used and the funding could not be read.
- The full text of the study with autistic children (Barchel 2026) could not be read: the dose of the oil used and side effects are not in the abstract. The study appears to be part of the autism program that the same center launched in the same period, on which the studies on the site's Autism page are also based (ClinicalTrials.gov NCT05212493; two oils with a CBD to THC ratio of 20 to 1); the oil's ratio is not stated in this article's abstract.
- Wilson 2026, Bharat 2026, Francisco 2023, Froude 2024, Suetani 2026, Ryan 2026, Stueber 2026, Leung 2020 and Bassalov 2024 were read from the abstract only. The content of the corrections published in the journal for Molina 2018 and Soler Artigas 2020 could not be read; the correction for Wilson 2026 was read on October 29, 2026: only the axis of one figure and the study counts in a table were corrected, and the results did not change.
- A study whose results were not released: a study in Israel that was to compare different cannabinoid oils (CBD, THC, CBDV or CBG) with placebo in adult ADHD (NCT05219370) was stopped in December 2022 with 8 people because of difficulty finding participants; there are no results in the registry. The record of the CBD oil study in children (NCT06542445) has not been updated since August 2024 (checked in October 2026).
- The licensing status in Turkey of the mouth spray containing THC and CBD (nabiximols) used in the ADHD study was not verified in this search.
Research history
Here we record what changed on this page, when and why, with dates. The newest change is at the top.
A study in 14 children with PANS that measured ADHD symptoms as a secondary measure was added to the uncontrolled data (Keating 2026, PMID 41513541, full text: Conners p = 0.028); in the previous search it had been left out because it was thought not to measure ADHD symptoms. Because there is no control group, the conclusion and the evidence level did not change.
The last sentence of the page's short summary was rewritten in a calmer, more guiding tone: instead of "Talk to your doctor before you start.", it now says whom you can talk with, and about what, if you are considering CBD. The conclusion and the strength of evidence did not change.
The correction to the Wilson 2026 meta-analysis published in the journal was read: only the axis of one figure and the study counts in a table were corrected; the results on this page did not change.
Related studies: Wilson 2026, published April 2026 (online March 16, 2026) (PMID 41856154, doi:10.1016/S2215-0366(26)00015-5, Correction: Lancet Psychiatry 2026, PMID 42302809, June 16, 2026: the axis of a figure and the study counts in the table were corrected, results unchanged). The same review is also in the site's anxiety, psychosis, depression, bipolar, sleep, substance use, autism and Tourette syndrome tables)
Older changes (2)
October 2026 additional review: sources found for this page during searches for other topics were read and added to the page. Secondary ADHD findings from Tourette syndrome and tic disorder studies were added to the text: in the 97-adult controlled study, the larger reduction in tics in those with ADHD was not statistically significant, and the result for ADHD symptoms was not published; in the uncontrolled study with 10 adolescents, the drop in ADHD score was not significant. These studies are in the table of the Tourette Syndrome page; the number of controlled studies in ADHD (1) did not change. The conclusion and strength of evidence did not change.
Page published. This first assessment reviewed 17 studies.