Cannabis use among adolescents and young adults has increased alongside legalization, commercialization, and higher product potency. However, evidence regarding the effectiveness of interventions to prevent or reduce cannabis use remains heterogeneous. To systematically synthesize evidence from randomized controlled trials (RCTs) evaluating behavioral, educational, psychosocial, family-based, and digital interventions targeting cannabis use among adolescents and young adults. Following PRISMA guidelines, MEDLINE, PsycINFO, CINAHL, Embase, and Web of Science were searched for randomized or cluster-randomized controlled trials involving participants aged 12–25 years. Study characteristics, intervention approaches, outcomes, and effectiveness were synthesized qualitatively. Of 973 records, 15 RCTs met the inclusion criteria. Studies varied in setting, intervention characteristics, delivery modality, and follow-up duration (2 months–7 years). School-based cognitive-behavioral interventions demonstrated the most consistent reductions in cannabis use and related harms by strengthening emotional regulation, problem-solving, coping skills, and social competence. Motivational interviewing, family-based, and digital interventions showed beneficial but variable effects. Behavioral interventions, particularly school-based cognitive-behavioral approaches, provide the strongest and most consistent evidence for reducing cannabis use and related harms among adolescents and young adults. However, methodological heterogeneity limits direct comparisons. Future well-powered RCTs with standardized outcome measures, longer follow-up, and implementation evaluations are needed to strengthen evidence-based prevention strategies.

Background: Sociodemographic and structural inequities shape the risk of alcohol-related harms among underage individuals. This study assessed disparities in alcohol-related emergency department (ED) visits, using the COVID-19 pandemic as a contextual backdrop to examine how these inequities shifted during a period of widespread disruption. Methods: This repeated cross-sectional study used pooled Nationwide Emergency Department Sample (NEDS) data (January 2019–December 2021) for individuals aged 12–20, comparing pre-COVID-19 (January 2019–March 2020) and during-COVID-19 (April 2020–December 2021) periods. Alcohol-related visits were identified via ICD-10-CM codes. Survey-weighted multivariable logistic regression estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for demographic, socioeconomic, and geographic factors, with interaction terms assessing period-related changes in disparities. Results: Sociodemographic disparities were the primary drivers of alcohol-related ED visits. Native American youth had markedly higher odds than White youth (OR = 3.68, 95% CI: 3.52–3.86), while Black, Hispanic, and Asian youth had lower odds. Uninsured (OR = 1.43) and charity-care youth also showed elevated odds. COVID-19 itself was not significantly associated with overall visits (OR = 1.03, p = 0.053), but disparities widened for Native American youth (OR = 1.20) and narrowed modestly for Black (OR = 1.04) and Medicaid-insured (OR = 1.05) youth, while other disparities remained unchanged. Conclusions: Persistent structural disparities, particularly by race/ethnicity and insurance status, drive underage alcohol-related ED utilization far more than the pandemic itself, underscoring the need for equity-focused prevention strategies targeting systemic barriers to care.