E-cigarettes, which contain liquid nicotine instead of tobacco, may encourage teenagers to become tobacco smokers, according to a Yale University School of Medicine study published today in the medical journal Pediatrics. 

In the new study, researchers surveyed more than 800 high school students over a three-year period. They found that teens who used e-cigarettes in 2013 were more than seven times as likely to smoke traditional cigarettes by 2014.

While some research suggests that e-cigarettes may help adults quit smoking, several previous studies have also found that for teens, vaping may lead to tobacco smoking.

More on e-cigarettes

Earlier studies, however, found that teens were just as likely to gravitate from traditional cigarettes to e-cigarettes as vice versa. This new research suggests that adolescents are more apt to start with e-cigarettes and then move on to tobacco, notes Jonathan Klein, M.D., M.P.H., a professor of pediatrics at the University of Illinois at Chicago, who wrote an editorial accompanying the study.

It appears that teens who use e-cigarettes "are becoming addicted, and then going on to traditional cigarette smoking,” he says.

Some other experts have a slightly different perspective. “These studies need to be taken seriously, but also need to be put in perspective,” says tobacco use researcher Kenneth Warner, Ph.D., professor emeritus of public health at the University of Michigan.

He notes that this study—and others like it—have not proven that vaping leads to a true nicotine habit, rather than short-term or occasional experimentation. “My concern is that studies like this one scare people into thinking that vaping is creating this new wave of smoking, and the data are just the opposite. Smoking in middle school and high school kids is dropping like a stone.”

Recent large surveys have found that both smoking and vaping in young people are declining. According to the Centers for Disease Control and Prevention, 4.9 million adolescents identified as tobacco users (which included e-cigarettes) in 2015, but only 3.9 million did the same in 2016. Of that number, young e-cigarette users dropped from 3 million in 2015 to just under 2.2 million in 2016.

Why Vaping Is Risky for Teens

E-cigarettes may be especially attractive to young people because they’re available in a wide variety of teen-friendly flavors, including Candy Crush, Cotton Candy, and Gummy Bear.

“They’re reminiscent of the candy cigarettes of a generation ago, which were designed as a way to introduce children to smoking,” says Harold Farber, M.D., an associate professor of pediatrics in the pulmonary section of Texas Children’s Hospital at Baylor College of Medicine, and chairman of the Tobacco Action Committee for the American Thoracic Society.  

But unlike those sugary treats of yesteryear, e-cigarettes are packed with nicotine, which may have a more significant effect on a teen’s brain than on an adult’s. 

“Kids’ developing brains are very sensitive to nicotine, and as a result they’re more likely to get addicted and then gravitate to other products like cigarettes, hookahs, and cigars,” Klein says. 

January 2017 report from the American Academy of Pediatrics, for instance, notes that exposure to nicotine at a young age may increase the likelihood of abusing other addictive substances. (Get more information from Consumer Reports on the health effects of nicotine here.)

E-cigarettes may affect teens’ health in other ways as well. A study published in April in the American Journal of Respiratory and Critical Care Medicine found that past or current e-cig users were nearly twice as likely to have a persistent cough, congestion, and bronchitis as never-users.

“The flavoring agents themselves contain ingredients such as propylene glycol and glycerin, respiratory irritants that are associated with lung scarring,” Farber says.

How to Talk to Teens

Even if you’re sure your teen hasn’t used e-cigarettes or tobacco, it’s important to have a conversation about them.

It’s difficult to ignore the numerous advertisements for e-cigs, and seeing them may make adolescents more likely to try vaping, according to research. An analysis of 22,000 middle and high school students, published in October in the journal Addictive Behaviors, found that those exposed to this type of marketing were about 30 percent more likely to report trying e-cigarettes.

The key is to keep the conversation natural. Rather than telling your teen you need to sit down and talk, ask him what he thinks about e-cigarettes when you pass a shop that sells them or when you see an advertisement for them.

Then explain that e-cigarettes are unhealthy because they contain tiny particles that can hurt his lungs, along with nicotine, which can affect his concentration and memory, among other concerns.

It’s important to stress to adolescents that their brain will continue developing until about age 25, so they’re more susceptible to the negative effects of nicotine, Klein adds.

The good news is that if they get through high school without vaping, they’re less likely to try e-cigs or regular tobacco later in life. “We know that initiation rates go down as teens turn into young adults, since they have higher executive function and better control of impulses,” Klein explains.