Surveillance of digital marketing strategies for online alcohol sales in Thailand: A comparative study before and after the 2025 selling time extension

BACKGROUND: Digital alcohol marketing may increase exposure to alcohol-related cues and undermine harm prevention. Changes in alcohol availability may influence online promotion, but before-after comparisons cannot establish policy effects. We compared alcohol marketing posts before and after Thailand's December 2025 extension of legal alcohol sales hours. METHODS: We conducted a repeated cross-sectional content analysis. Of 1419 eligible Thai-language posts, the main analysis included 1384 posts from Facebook, Instagram and LINE (811 pre-reform; 573 post-reform). AI-assisted coding combined dictionary and contextual rules with manual validation. Modified Poisson models estimated prevalence ratios adjusted for platform and source type, with account-clustered standard errors. All 14 content features were exploratory, with false discovery rate correction. RESULTS: Restaurants, pubs and bars contributed 40.7% of pre-reform and 45.9% of post-reform posts, while influencers contributed 17.6% and 11.7%. The higher share from official brand pages disappeared after excluding sponsored posts, which were captured only post-reform. Adjusted estimates indicated higher prevalence of evasive language (aPR 1.12, 95% CI 1.01-1.24) and lower prevalence of urgency (0.84, 0.69-1.01) and fear-of-missing-out (FOMO) messaging (0.87, 0.75-1.02); none remained statistically significant after FDR correction (minimum q = 0.408). CONCLUSION: Posts differed mainly in source composition. Lower urgency and FOMO messaging were compatible with a reduction in the relevance of time-limited purchasing appeals following the extension, but seasonality, concurrent advertising-law changes and retrieval differences prevent attribution to the reform. Longer-term surveillance and stronger comparative designs are needed to evaluate whether changes in alcohol availability are associated with changes in marketing, exposure and alcohol-related outcomes.