Introduction:
The current information demonstrates that the use of electronic cigarettes (e-cigarettes) is increasing among young adults. There is a lot of information in social media about the pros and cons of e-cigarettes, with conflicting results.

Objectives:
Therefore, this cross-sectional study aimed to study the knowledge and attitude towards e-cigarettes among students studying at a university in northern Thailand who smoked ordinary cigarettes and/or e-cigarettes.

Methods:
The data were collected using a self-administered questionnaire from 408 university students who smoked ordinary cigarettes and/or e-cigarettes between January to April 2019. The study protocol was approved by the Ethics Review Committee, Faculty of Pharmacy, Chiang Mai University. The statistical analyses were performed with the STATA software.

Results:
The results showed that regarding the knowledge towards e-cigarettes, the average score was 5.9 ± 2.1 from a total score of 12. The study indicated that 85.5% of the participants understood that nicotine was the cause of e-cigarettes addiction. The 2 most misunderstood questions were e-cigarettes could cause bronchitis, and propylene glycol in e-cigarettes could cause respiratory and eye irritation because only 22.5% and 24.7%, respectively could answer these questions correctly. The health-sciences students had significantly higher knowledge scores than arts/social sciences students and science/technology students. Regarding the attitude towards e-cigarettes, 60.3% believed that e-cigarettes were less dangerous to human health than ordinary cigarettes. However, 51.7% was hesitant that smoking e-cigarettes had a negative effect on human health in the long term. In addition, 40.7% disagreed that smoking e-cigarettes could help smokers to be accepted among friends and to socialize.

Conclusion(s):
In conclusion, the majority of students had insufficient knowledge of e-cigarettes. Most of them believed that e-cigarettes were less dangerous than ordinary cigarettes and uncertain about negative effects on chronic use.