Background: Acute diarrhoea remains a foremost cause of morbidity and preventable mortality among children under five years of age in India, disproportionately affecting rural and peri-urban populations. Despite the national integration of zinc supplementation into the Integrated Management of Neonatal and Childhood Illness (IMNCI) guidelines, uptake in rural Tamil Nadu remains inconsistent. Chengalpattu district, characterised by pockets of poverty, agricultural dependency, and suboptimal sanitation coverage, presents a context in which the real-world effectiveness of zinc supplementation warrants empirical investigation. Objective: To assess the prevalence and patterns of zinc supplementation use among caregivers of children under five presenting with acute diarrhoea, and to compare the duration and severity of diarrhoeal illness between children who received zinc supplementation and those who did not, in rural Chengalpattu district, Tamil Nadu. Methods: A community-based cross-sectional study was conducted across 12 primary health centre catchment areas in rural Chengalpattu district over a six-month period (January–June 2009). A total of 320 children aged 6 to 59 months who had experienced an acute diarrhoeal episode within the preceding 30 days were enrolled using multistage stratified random sampling. Structured interviewer-administered questionnaires were used to collect data on sociodemographic characteristics, zinc supplementation practices, diarrhoea duration, stool frequency, and healthcare-seeking behaviour. Disease severity was assessed retrospectively using the Modified Vesikari Score. Data were analysed using SPSS version 26.0; chi-square tests, independent sample t-tests, and binary logistic regression were applied as appropriate. Results: Among 320 enrolled children, 178 (55.6%) had received zinc supplementation during their most recent diarrhoeal episode. Children in the zinc-supplemented group experienced a significantly shorter mean diarrhoeal duration (3.1 ± 1.2 days) compared to unsupplemented children (4.6 ± 1.5 days; p<0.001). Stool frequency by Day 5 was markedly lower in the zinc group (1.6 ± 0.8 versus 2.9 ± 1.2; p<0.001). Mild disease severity was observed in 38.2% of zinc-supplemented children versus 19.4% in the unsupplemented group (p=0.002). Logistic regression identified maternal education above secondary level (OR 2.14; 95% CI: 1.38–3.32), health worker contact (OR 2.87; 95% CI: 1.74–4.73), and access to a government health facility within 3 km (OR 1.96; 95% CI: 1.22–3.14) as independent predictors of zinc supplementation uptake. Conclusion: Zinc supplementation is significantly associated with reduced duration and severity of acute diarrhoea in under-five children in rural Chengalpattu district. Targeted community-level strategies to enhance caregiver awareness and health worker engagement are essential to improve zinc supplementation coverage within existing national diarrhoeal disease management programmes.

Zinc supplementation, acute diarrhoea, under-five children, rural Tamil Nadu, Chengalpattu district, cross-sectional study, Modified Vesikari Score, community health, IMNCI, paediatric diarrhoea.