Uncovering Substance Use and Its Drivers Among Youth in Delhi's Slums – a Cross-Sectional Insight

India has the largest adolescent population in the world, 253 million, and every fifth person is between 10-19 years. Prevalence of substance use among teenagers living in slums has increased recently and is growing at an alarming rate in many developing nations. Study aims to estimate the prevalence of substance use and its determinants among youth of slum settings in Delhi, India; using WHO-ASSIST. Study used cross-sectional primary data, collected in 2021–2022 from the youth 15-24 years (male) living in different slums of Delhi. A total of 517 male youth was surveyed. Descriptive statistics, Chi square test and binary logistic regression along with WHO ASSIST tool were used to assess the substance use. Respondents (18 years or less) seem to be more prone to high-risk substance use, especially for opioids, inhalants and sedatives. Tobacco and alcohol remain consistent and most commonly used substances across age groups showing moderate risk use among all ages. The risk levels for different substances are influenced by a variety of background factors, with age, wealth, education, parents' behaviors, and housing type showing the strongest associations. These findings suggest a need for targeted interventions, especially focusing on older age groups, unemployed youth, and those from middle-income families. Absence of effective legislation on curbing availability of substance use products and poor community awareness on their harmful effects creates a vicious cycle contributing to rising burden NCDs in India. A multi-pronged approach combining prevention, treatment, regulation, and community engagement is essential for addressing substance use among youth in Delhi slums. Collaborating with local stakeholders, government agencies, NGOs, and healthcare providers will be crucial for the intervention's success.