Background: Little is known about characteristics of electronic cigarette users. The aim of this study is to investigate characteristics of dual users of both conventional cigarettes and e-cigarettes compared to only e-cigarette users among Korean adolescents.

Methods: We used a data pool from the 2013 Korean Youth Risk Behavior Web-based Survey containing 2,074 electronic cigarette users among Korean middle and high school students.

Results: Dual users of both conventional cigarettes and e-cigarettes were 75.4% in males, and 67.3% in females among current e-cigarette users. Gender, school level, academic performance, stress, weekly allowance, experience of alcohol drinking and anti-smoking education were associated with dual use of conventional cigarettes and e-cigarettes among Korean youth. The results from regressions show that: male students (aOR 1.59; 95% CI, 1.20-2.12), high school students (aOR 1.69; 95% CI 1.30-2.19), those who had reported high level of stress (aOR 1.46; 95% CI, 1.09-1.92), and those who had experienced alcohol drinking (aOR 3.82; 95% CI, 2.64-5.52) were more likely to become dual user. Students who had received more than KRW 40,000 (aOR 1.75; 95% CI, 1.24-2.47) were more likely to use both e-cigarettes and conventional cigarettes than received less than KRW 10,000. Moreover, students who had participated in smoking prevention program (aOR 1.30; 95% CI, 1.05-1.67) were more likely to become dual user.

Conclusion: Dual use of both conventional cigarettes and e-cigarettes is common among e-cigarette users in South Korea. Dual use can threaten public health. Therefore, further research should investigate safety of dual use. Moreover, ongoing surveillance of dual use is recommended for public health planning.