Adolescents uncertain about risks of marijuana, e-cigarettes

Adolescents get clear messages about the harms of smoking cigarettes, but they receive conflicting or sparse information about marijuana and e-cigarettes, a study finds.

A new study indicates that adolescents were confused about whether e-cigarettes are harmful.

Teenagers are very familiar with the risks of smoking cigarettes, but are much less sure whether marijuana or e-cigarettes are harmful, according to a new study by researchers at the Stanford University School of Medicine.

While adolescents get clear messages from their families, teachers, peers and the media about the harms of smoking cigarettes, they receive conflicting or sparse information about the harms of marijuana and e-cigarettes, the study showed.

The findings were published online June 23 in the Journal of Adolescent Health.

“Kids were really good at describing the harmful things that happen with cigarette smoking, but when we asked about other products, there was a lot of confusion,” said the study’s lead author, Maria Roditis, PhD, a postdoctoral scholar in adolescent medicine.

“We’re good at delivering messaging that cigarettes are harmful, but we need to do a better job with other products that teens may smoke,” added Bonnie Halpern-Felsher, PhD, professor of pediatrics in adolescent medicine and the study’s senior author. “We don’t want the message kids get to be ‘cigarettes are bad, so everything else might be OK.’”

Tripling of e-cigarette use

Halpern-Felsher and Roditis compared teens’ knowledge of cigarettes, e-cigarettes and marijuana because they heard from teachers, parents and youth that anti-smoking efforts needed to address more than just conventional cigarettes. The need is borne out by other research: A recent study from the Centers for Disease Control shows that middle- and high-school students’ use of e-cigarettes tripled from 2013 to 2014, eclipsing conventional cigarettes as the most common tobacco product in this age group.

Bonnie Halpern-Felsher

Halpern-Felsher and Roditis studied 24 adolescents who attended high school in a Northern California school district known to have high rates of substance use. The students participated in small-group discussions about their perceptions of the risks and benefits of conventional cigarettes, e-cigarettes and marijuana. They also discussed how they learned about these products. The researchers analyzed the themes that emerged in the discussions.

Students perceived little or no benefit, as well as several detrimental effects, of smoking conventional cigarettes, such as yellowed teeth, bad breath and long-term disease risk. They also said their social norms often discouraged smoking conventional cigarettes. For instance, even smoking marijuana rolled in paper was considered weird because it looks like a cigarette.

Perceptions versus reality

However, students saw getting high as a benefit to smoking marijuana, and perceived it as safer and less addictive than tobacco. They were unsure whether marijuana posed health risks, and also described being under peer pressure to smoke marijuana.

With respect to e-cigarettes, students perceived some benefits, including thinking e-cigarettes looked good, and were unsure of the risks.

Students’ sources of information about the three products were varied. The media, families and teachers all warned against the use of conventional cigarettes. Students also got messages from these sources discouraging use of marijuana, but said it was difficult to refuse the drug because its use was so prevalent among their peers. Students received few, mostly informal, messages about e-cigarettes: They said they saw family members using them to try to quit conventional cigarettes, and also saw peers using them.

Students hear a lot of talk about conventional cigarettes, some about marijuana and very little about e-cigarettes.

The findings could help shape future messages about marijuana and e-cigarettes, the study’s authors said. For instance, students need to hear about the addictive potential of both products; about the risks of smoking any form of plant matter, which is similar between conventional cigarettes and marijuana; and about the presence of nicotine in e-cigarettes. In addition, flavorants in e-cigarettes may raise the risk of obstructive lung disease.

“Students hear a lot of talk about conventional cigarettes, some about marijuana and very little about e-cigarettes,” Halpern-Felsher said. “That gap needs to be filled in classrooms and by health-care providers, parents and the media. We don’t want to leave one product behind and leave teens with the impression that, ‘Maybe this is the product I can use.’”

Roditis was a postdoctoral scholar at the University of California-San Francisco while the data was being collected. The study was funded by National Cancer Institute (grant CA-113710).

More information about the Department of Pediatrics, which also supported the research, is available at

Stanford Medicine integrates research, medical education and health care at its three institutions - Stanford University School of Medicine, Stanford Health Care (formerly Stanford Hospital & Clinics), and Lucile Packard Children's Hospital Stanford. For more information, please visit the Office of Communication & Public Affairs site at

Leading in Precision Health

Stanford Medicine is leading the biomedical revolution in precision health, defining and developing the next generation of care that is proactive, predictive and precise. 

A Legacy of Innovation

Stanford Medicine's unrivaled atmosphere of breakthrough thinking and interdisciplinary collaboration has fueled a long history of achievements.