BACKGROUND AND AIMS: Cocaine use disorder (CUD) is a significant public health concern for which no efficacious pharmacological interventions are available. Cannabidiol (CBD) has attracted considerable interest as a promising treatment for addiction. This study tested CBD efficacy for reducing craving and preventing relapse in people with CUD.

DESIGN: Single-site double-blind randomized controlled superiority trial comparing CBD with placebo.

SETTING AND PARTICIPANTS: Centre Hospitalier de l'Université de Montréal, Canada. Seventy-eight adults (14 women) with moderate to severe CUD participated.

INTERVENTION: Participants were randomly assigned (1 : 1) by stratified blocks to daily 800 mg CBD (n = 40) or placebo (n = 38). They first underwent an inpatient detoxification phase lasting 10 days. Those who completed this phase entered a 12-week outpatient follow-up.

MEASUREMENTS: Primary outcomes were drug-cue-induced craving during detoxication and time-to-cocaine relapse during subsequent outpatient treatment.

FINDINGS: During drug-cue exposure, craving scores [mean ± standard deviation (SD)] increased from baseline by 4.69 (2.89) versus 3.21 (2.78) points, respectively, in CBD (n = 36) and placebo (n = 28) participants [confidence interval (CI) = -0.33 to 3.04; P = 0.069; Bayes factor = 0.498]. All but three participants relapsed to cocaine by week 12 with similar risk for CBD (n = 34) and placebo (n = 27) participants (hazard ratio = 1.20, CI = 0.65-2.20, P = 0.51; Bayes factor = 0.152). CBD treatment was well tolerated and associated mainly with diarrhoea.

CONCLUSIONS: CBD did not reduce cocaine craving or relapse among people being treated for CUD.