Cannabis-based medicines are showing increasingly strong evidence for reducing tics in Tourette syndrome. In this systematic review and meta-analysis involving 306 adults, cannabinoid-based treatments significantly reduced tic severity on the Yale Global Tic Severity Scale and also significantly reduced premonitory urges—the uncomfortable sensations that often precede tics. The analysis found a mean YGTSS reduction of 13.29 points and a mean PUTS reduction of 4.09 points, providing quantitative evidence that cannabinoids can meaningfully improve two core features of Tourette syndrome.

“Background: Tourette syndrome (TS) involves motor and vocal tics, often with obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD). Cannabis-based medicines (CBMs) are a potential therapy due to their interaction with the endocannabinoid system, potentially reducing tics and associated symptoms. Compared to antipsychotics, CBMs may offer improved tolerability and fewer side effects. Although evidence is limited, emerging studies suggest their potential to improve quality of life in TS. This review was registered with PROSPERO (CRD420251088633).

Aim: To evaluate the effectiveness of CBMs in treating TS.

Methods: We systematically searched PubMed, Google Scholar, ScienceDirect, and the Cochrane Collaboration Database for cohort studies and randomized controlled trials (RCTs) up to July 2, 2025. Data extraction included study characteristics and efficacy outcomes measured by the Yale Global Tic Severity Scale (YGTSS) and Premonitory Urge for Tics Scale (PUTS). Meta-analysis using Review Manager 5.4 compared pre- and post-treatment scores using mean difference (MD) and 95% confidence intervals (CI).

Results: From 1,105 screened articles, eight studies met inclusion criteria for the review, and seven were included in the meta-analysis, involving 306 adult TS patients. CBMs significantly reduced YGTSS scores (MD = – 13.29, 95% CI [-21.67 to – 4.91], P = 0.002) and PUTS scores (MD = – 4.09, 95% CI [-7.24 to – 0.93], P = 0.01).

Conclusion: CBMs show promising potential in reducing tics and premonitory urges in TS. Larger, placebo-controlled trials are needed to confirm efficacy, ensure safety, and optimize dosing.”

https://pubmed.ncbi.nlm.nih.gov/42229830

“Cannabis-based medicines significantly reduced tic severity in Tourette syndrome.”

https://www.ibroneuroscience.org/article/S0306-4522(26)00367-2/abstract

“Medicinal cannabis has been trialled for Tourette syndrome in adults, but it has not been studied in adolescents. This open-label, single-arm trial study evaluated the feasibility, acceptability and signal of efficacy of medicinal cannabis in adolescents (12-18 years), using a Δ9-tetrahydrocannabinol:cannabidiol ratio of 10:15, with dose varying from 5 to 20 mg/day based on body weight and response.

The study demonstrated feasibility of recruitment, acceptability of study procedures, potential benefits and a favourable safety profile, with no serious adverse events. Commonly reported adverse events were tiredness and drowsiness, followed by dry mouth.

Statistically significant improvement was observed in parent and clinician reports on tics (paired t-test P = 0.003), and behavioural and emotional issues (paired t-test P = 0.048) and quality of life as reported by the parent and young person (paired t-test P = 0.027 and 0.032, respectively). A larger-scale, randomised controlled trial is needed to validate these findings.”

https://pubmed.ncbi.nlm.nih.gov/40636988/

https://www.cambridge.org/core/journals/bjpsych-open/article/medicinal-cannabis-for-tics-in-adolescents-with-tourette-syndrome/1A788DF6DE778600989CD90AF7A604D0

“Introduction: Medicinal cannabis (MC) has potential therapeutic effects in Tourette Syndrome (TS), however there has been limited research in adolescent patients. This pilot study aimed to investigate the feasibility of conducting a randomized placebo-controlled crossover trial of MC in adolescents with TS. 

Method: This was a phase I/II double-blind, cross-over pilot study comparing MC with matched placebo in adolescents aged 12-18 years with TS. The active medication was Δ9-tetrahydrocannabinol (THC) 10 mg/mL and CBD 15 mg/mL in peppermint-flavored medium-chain triglyceride oil. The dose titration schedule was stratified into two participant weight bands: below 50 kg (max THC 10 mg/day) or ≥50 kg (max THC 20 mg/day). Each treatment phase lasted 10 weeks, with a 4-week washout period. 

Results: Ten adolescents were randomized (mean age 14.8 years, 50% male) and seven completed the full study protocol. Two adolescents discontinued due to adverse events (one on MC, one placebo) and one was lost to follow-up. The most common adverse event was dizziness (67%). There were no serious adverse events. Among actively enrolled participants, protocol adherence was excellent: study visits 100%, blood test completions 100%, and online questionnaire completion 97.6%. Medication adherence was acceptable in 63.6%. Parents reported a high degree of study design acceptability. On the Clinical Global Impression-Improvement scale, three participants were rated as much improved on MC compared with one on placebo at 10 weeks. 

Discussion: The findings suggest that the study protocol is feasible and acceptable to patients with TS and their families. A fully powered study is needed to evaluate the efficacy of MC in adolescent TS.”

https://pubmed.ncbi.nlm.nih.gov/40082070/

https://www.liebertpub.com/doi/10.1089/can.2024.0188

“This randomized controlled crossover trial examined the use of oral tetrahydrocannabinol (THC) with cannabidiol (CBD) to reduce tics in patients with severe Tourette syndrome. Treatment with THC and CBD for 6 weeks led to a significant reduction in tics as measured by the total tic score on the Yale Global Tic Severity Scale, without major adverse effects.”

https://pubmed.ncbi.nlm.nih.gov/38320199/

“BACKGROUND

Tourette syndrome is characterized by chronic motor and vocal tics. There is preliminary evidence of benefit from cannabis products containing Δ⁹-tetrahydrocannabinol (THC) and that coadministration of cannabidiol (CBD) improves the side-effect profile and safety.

METHODS

In this double-blind, crossover trial, participants with severe Tourette syndrome were randomly assigned to a 6-week treatment period with escalating doses of an oral oil containing 5 mg/ml of THC and 5 mg/ml of CBD, followed by a 6-week course of placebo, or vice versa, separated by a 4-week washout period. The primary outcome was the total tic score on the Yale Global Tic Severity Scale (YGTSS; range, 0 to 50 [higher scores indicate greater severity of symptoms]). Secondary outcomes included video-based assessment of tics, global impairment, anxiety, depression, and obsessive-compulsive symptoms. Outcomes were correlated with plasma levels of cannabinoid metabolites. A computerized cognitive battery was administered at the beginning and the end of each treatment period.

RESULTS

Overall, 22 participants (eight female participants) were enrolled. Reduction in total tic score (at week 6 relative to baseline) as measured by the YGTSS was 8.9 (±7.6) in the active group and 2.5 (±8.5) in the placebo group. In a linear mixed-effects model, there was a significant interaction of treatment (active/placebo) and visit number on tic score (coefficient = −2.28; 95% confidence interval, −3.96 to −0.60; P=0.008), indicating a greater decrease (improvement) in tics under active treatment. There was a correlation between plasma 11-carboxy-tetrahydrocannabinol levels and the primary outcome, which was attenuated after exclusion of an outlier. The most common adverse effect in the placebo period was headache (n=7); in the active treatment period, it was cognitive difficulties, including slowed mentation, memory lapses, and poor concentration (n=8).

CONCLUSIONS

In severe Tourette syndrome, treatment with THC and CBD reduced tics and may reduce impairment due to tics, anxiety, and obsessive-compulsive disorder; although in some participants this was associated with slowed mentation, memory lapses, and poor concentration.”

https://evidence.nejm.org/doi/10.1056/EVIDoa2300012

“Background: The multicenter, randomized, double-blind, parallel-group, phase IIIb CANNA-TICS (CANNAbinoids in the treatment of TICS) trial showed clear trends for improvement of tics, depression, and quality of life with nabiximols versus placebo in adult patients with Gilles de la Tourette syndrome and other chronic tic disorders. Although in general nabiximols was well tolerated, it is unclear whether treatment using this cannabis extract influences driving skills in patients with chronic tic disorders. 

Methods: Here we report results of the “Fitness to Drive” substudy of the CANNA-TICS trial. The key endpoint was fitness to drive as a binary criterion with a computerized assessment at baseline and after 9 weeks of stable treatment (week 13) with nabiximols or placebo. A patient was considered unfit to drive according to the German Federal Highway Research Institute guidelines. 

Results: In the substudy, a total of 64 patients (76.6% men, mean±standard deviation of age: 36.8±13.9) were recruited at two study sites. The number of patients who were fit to drive increased from 24 (55.8%) at baseline to 28 (71.8%) at week 13 among 43 patients treated with nabiximols, and decreased from 14 (66.7%) to 10 (52.6%) among 21 patients who received placebo. The risk difference (nabiximols – placebo) was 0.17 (95% confidence interval=-0.08 to 0.43) in favor of nabiximols. Specifically, only 2 of 24 (8.3%) patients in the nabiximols, but 4 of 14 (28.6%) patients in the placebo group changed for the worse from fit (at baseline) to unfit (at week 13) to drive, whereas 8 of 19 (42.1%) patients in the nabiximols, and only 2 of 7 (28.6%) patients in the placebo group improved from unfit to fit. 

Conclusion: Treatment with nabiximols does not impair skills relevant to driving in those patients with tic disorders who were fit to drive at baseline and even improved fitness to drive in a subset of patients who were unfit to drive before start of treatment.”

https://pubmed.ncbi.nlm.nih.gov/38265476/

https://www.liebertpub.com/doi/10.1089/can.2023.0114