INTRODUCTION: Adolescent deviant behaviors can severely hinder their healthy development. This study explores the relationship between tobacco consumption and sexual behavior in Korean adolescents. METHODS: This is a secondary dataset analysis of the pooled KYRBS cross-sectional studies from 2018 to 2022. Sexual behavior generally refers to physical contact or interactions related to sex. In this study, sexual behavior primarily refers to intercourse. A logit model was applied to examine the relationship between different types of tobacco use and the initiation of sexual behavior. Furthermore, data from the KYRBS 2018-2021 were used to analyze the time-related patterns in the connection between tobacco use and the first occurrence of sexual behavior among adolescents, with a focus on the moderating role of gender. RESULTS: Tobacco use among adolescents was positively associated with the occurrence of sexual behavior. After adjusting for other variables, adolescents who use ordinary cigarettes (AOR=7.85
95% CI: 7.49-8.23), nicotine e-cigarettes (AOR=8.21
95% CI: 7.80-8.64), or combustible e-cigarettes (AOR=9.86
95% CI: 9.26-10.49) were more likely to engage in sexual behavior than non-users. Further research indicates that the earlier an individual reported beginning smoking tobacco, the earlier their first sexual encounter occurs, the correlation coefficient is 0.526 (p<
0.01). Additionally, in the moderation analysis, the male group weakened the trend in the time to first tobacco use and first sexual behavior. CONCLUSIONS: The use of different types of tobacco among Korean adolescents is strongly associated with sexual behavior. Adolescents are starting to engage in sexual activity at a younger age, especially males. Thus, providing reproductive health education to adolescent smokers could enhance their sexual decision-making. Furthermore, implementing tobacco cessation and sexual education for adolescents necessitates the development of gender-specific strategies to meet the distinct needs of males and females.