To provide comprehensive estimates of the prevalence of psychoactive substance use, specifically alcohol, cigarettes and marijuana, and factors associated with their use among school-going adolescents in 25 African countries.

We used a pooled cross-sectional dataset from the publicly available Global School-based Health Survey (GSHS) from 25 African countries. We used descriptive statistics to estimate the prevalence of alcohol, cigarette and marijuana use as well as their dual use among adolescents aged 11–16 years. Additionally, we used logistic regressions to model factors associated with the use of each substance, with adjusted Odds Ratios (aORs) and their 95% Confidence Intervals (CIs) as the measures of association.

The study focused on school-going adolescents aged 11–16 years in 25 African countries that have conducted the GSHS between 2003 and 2017.

The key outcome measure is the proportion of adolescents who have used a specific substance in the past 30 days. These substances include: (1) alcohol, (2) cigarettes, (3) marijuana, (4) alcohol and cigarettes, (5) cigarettes and marijuana and (6) alcohol and marijuana.

The prevalence of alcohol use among adolescents was 9.5% (95% CI 8.4% to 10.7%), that of cigarette smoking was 6.2% (95% CI 5.0% to 7.6%), and it was 3.4% (95% CI 2.7% to 4.2%) for marijuana. The prevalence of dual use of alcohol and cigarettes was 3.1% (95% CI 2.4% to 3.9%), that of alcohol and marijuana was 2.0% (95% CI 1.5% to 2.5%), and it was 1.4% (95% CI 1.1% to 1.8%) for cigarettes and marijuana. The prevalence of cigarette smoking was significantly higher among boys than girls. However, there was no statistically significant difference in the prevalence of alcohol or marijuana by sex. Having parents who smoke any tobacco products, being bullied, missing school without permission and experiencing sadness and hopelessness were positively associated with being a current user, irrespective of substance type.

There is a need for comprehensive, current data on substance use among adolescents. Interventions that tackle bullying, reduce school absenteeism, build resilience against difficult situations and increase self-efficacy to resist the use of these substances have the potential to curb substance use among adolescents in Africa.