Background: There is a co-occurrence of adolescents’ substance use and sexual practices, with an important impact on their health and health behaviours; however, limited research is conducted with adolescents. The aim of this study was to estimate the prevalence of substance use (alcohol and/or other substances) in sexual contexts and to identify its associated factors among adolescents, comparing boys and girls. Methods: Cross-sectional study with data from 6352 adolescents aged 14­­­–18 years from the DESKcohort project. Prevalence of alcohol and/or other substance use in sexual contexts (OSUSC) stratified by sex were calculated, according to axes of inequality, psychosocial factors, and sexual health and health variables. Poisson regression models with robust variance were calculated to analyse potential associations with independent variables. Results: Girls (51.4% of the sample) reported a higher prevalence of alcohol use in sexual contexts than boys (43.9% vs 33.9%, P < 0.001), whereas OSUSC was reported by 12–14% of adolescents. Alcohol and/or OSUSC were associated to several risk practices, such as having multiple sexual partners and inconsistent condom use, for both sexes. Also, sexual minority orientation students, natives, and students with disadvantaged socioeconomic positions (SEPs) presented higher prevalences of substance use in sexual contexts. Conclusions: These findings suggest that substance use in sexual contexts reflects a broader pattern of co-occurring risky behaviours rather than intentional sexualised substance use. Some vulnerable groups include girls, adolescents with a minority sexual orientation, and students with disadvantaged SEPs. These findings underscore the need for holistic interventions targeting adolescents’ health, addressing substance use and sexual risk behaviours simultaneously to reduce potential consequences such as unplanned pregnancies and sexually transmitted infections.

This study analyzes the impact of the COVID-19 pandemic on alcohol, cannabis, and tobacco use among adolescents aged 14–19 in Central Catalonia across three periods. Data were obtained from two waves of the DESKcohort project. The first wave (n = 4641) was pre-COVID-19 and the second wave was divided into two phases: post-COVID-19 with restrictions (n = 3478) and post-COVID-19 without restrictions (n = 2900). The prevalence of monthly binge drinking, cannabis use in the last 30 days, and daily tobacco use was calculated. Poisson regression models estimated adjusted prevalence ratios (aPR) comparing two post-pandemic phases to the pre-pandemic baseline. Binge drinking increased during the restrictions among girls [aPR = 1.5 (95%CI: 1.1–2.1)] and boys [aPR = 1.7 (95%CI: 1.3–2.3)]. Cannabis use decreased during restrictions and remained low post-pandemic, especially among girls [aPR = 0.6 (95%CI: 0.5–0.8)] and boys in the 4th Compulsory Secondary Education (CSE) [aPR = 0.4 (95%CI: 0.3–0.6)], and girls in the 2nd Post-Compulsory Secondary Education/Intermediate-Level Training Cycles (PCSE/ILTC) [aPR = 0.7 (95%CI: 0.6–0.9)]. Daily tobacco use also dropped among boys in the 4th year of CSE [aPR = 0.5 (95%CI: 0.3–0.7)] and girls in the 2nd year of PCSE/ILTC [aPR = 0.7 (95%CI: 0.6–0.9)]. The COVID-19 pandemic has created a unique opportunity to reassess patterns of adolescent substance use in a context of sudden social disruption. The findings highlight the need to denormalize alcohol and tobacco use and promote healthier adolescent behavior through education.