Background: Previous studies indicate that, despite legal restrictions, northeastern states have the highest prevalence of underage drinking, with Arunachal Pradesh leading. Considering the harms associated with underage drinking, assessing its magnitude, and contributing factors is crucial.

Methods: Using the Minimum Legal Drinking Age (MLDA) and the state-level National Family Health Survey (NFHS-5), data from 7,398 individuals aged 15–20 years were used to assess the district-wise prevalence of underage drinking in Arunachal Pradesh. Further bivariate and multivariate regression analyses were undertaken to identify the significant predictors of underage drinking.

Results: The prevalence of underage drinking in Arunachal Pradesh ranged from 4% to 20% across the districts. The Upper Subansiri district had the highest prevalence (20%). Females were less likely to drink alcohol than males (adjusted odds ratio (aOR) 0.55; 95% confidence intervals (CI) 0.44, 0.69). The 18–20 year-olds (aOR 2.28; 95% CI 1.82, 2.86), married (aOR 1.99; CI 1.44, 2.76), rural residents (aOR 2.25; CI 1.62, 3.12), and those who belong to the poorest wealth quintile were more likely to drink alcohol. Tobacco use was also strongly associated with underage drinking. The odds of drinking alcohol were 30 times higher among tobacco users than non-users (aOR 30.45; 95% CI 24.22, 38.28).

Conclusions: Underage drinking is prevalent across all districts of Arunachal Pradesh. Socio-demographic factors are strongly associated with underage drinking. There is a pressing need for strict enforcement of the MLDA, restricting alcohol availability, and community-based interventions to create awareness among the young population and parents about the harms of underage drinking in Arunachal Pradesh.