E-cigarette is now creating a new route to conventional smoking and nicotine addiction for teenagers though it was promoted as a way to quit regular cigarettes, says a study.
Adolescents who used the devices were more likely to smoke cigarettes and less likely to quit smoking.
"Despite claims that e-cigarettes are helping people quit smoking, we found that e-cigarettes were associated with more, not less, cigarette smoking among adolescents," said Lauren Dutra, a post-doctoral fellow at the University of California - San Francisco's (UCSF) centre for tobacco control research and education.
The study of nearly 40,000 youth found that e-cigarettes usage among middle and high school students doubled between 2011 and 2012, from 3.1 to 6.5 percent.
E-cigarettes are likely to be gateway devices for nicotine addiction among youth, opening up a whole new market for tobacco.
"It looks like the wild west marketing of e-cigarettes is not only encouraging youth to smoke them but also it is promoting regular cigarette smoking among youth," said senior author Stanton A. Glantz, a professor at the centre for tobacco control research and education.
E-cigarettes are battery-powered devices that look like cigarettes and deliver an aerosol of nicotine and other chemicals.
Promoted as safer alternatives to cigarettes and smoking cessation aids, the devices are rapidly gaining popularity among adults and youth worldwide.
These are sold in flavours such as chocolate and strawberry that are banned in conventional cigarettes because of their appeal to youth.
The authors found that the devices were associated with higher odds of progression from experimenting with cigarettes to becoming established cigarette smokers.
Additionally, adolescents who smoked both conventional cigarettes and e-cigarettes smoked more cigarettes per day than non-e-cigarette users, said the study published in the journal JAMA Pediatrics.