N-Acetylcysteine Did Not Help Youth Quit Cannabis Without Contingency Management

In a double-blind RCT of 192 treatment-seeking youth (ages 14-21) with CUD, N-acetylcysteine 1200 mg twice daily for 12 weeks showed no advantage over placebo on any cannabis use outcome. The proportion of negative urine tests did not differ (RR=0.93, p=0.80), nor did self-reported abstinence (RR=1.02, p=0.93). Both groups reduced cannabis use over time, but there was no between-group difference. NAC caused significantly more GI side effects (64% vs 39%).

Double-blind, placebo-controlled randomized trial. 192 treatment-seeking youth (ages 14-21) with CUD randomized to NAC 1200 mg or placebo twice daily for 12 weeks. All received weekly medical management and brief behavioral counseling. Primary outcome: proportion of negative urine cannabinoid tests during treatment.

A previous trial of NAC for youth CUD showed positive results, but that trial included contingency management (paying participants for negative drug tests). This follow-up demonstrates that NAC alone, without that behavioral platform, is not effective, fundamentally reframing what drove the earlier positive findings.

This negative result is actually informative: it suggests that contingency management, not NAC, was the active ingredient in prior positive studies. It redirects future CUD treatment research toward behavioral interventions and away from NAC as a pharmacological solution.

Treatment-seeking youth may differ from the broader CUD population. Weekly medical management and counseling provided to both groups may have diluted any NAC effect. 12-week duration may be insufficient. High GI side effect rate may have functionally unblinded some participants.