Children, adolescents, and young adults who vape are about three times more likely to start smoking cigarettes than non-users, according to the most comprehensive study yet on the wider risks of e-cigarette use in young people.

UK researchers analyzed 56 reviews of studies involving millions of participants under age 25 across 14 countries. Published in Tobacco Control, the findings showed vaping may also lead young people to smoke more frequently and heavily—a phenomenon known as the “gateway effect.”

The review also linked e-cigarette use to higher risks of substance use (marijuana, alcohol, and stimulants), asthma, lung injuries, and mental health problems. While more research is needed to prove direct cause and effect, lead author Dr. Su Golder called the consistency of evidence “striking.”

“Across multiple studies, young people who use e-cigarettes are more likely to smoke in the future,” said Golder, an associate professor in health sciences at the University of York. “These findings support stronger public health measures to protect teens from the risks associated with vaping.”

The findings come amid what the World Health Organization (WHO) calls an “alarming” surge in youth vaping. In the US, e-cigarettes were the most commonly used tobacco product last year [2024] among middle and high school students, with 5.9% reporting current use. The legal minimum age to purchase tobacco products, including e-cigarettes, is 21.

Concerns about e-cigarettes, most of which contain nicotine, have grown as evidence suggests vaping can damage lungs as much as smoking. Studies show e-cigarettes produce harmful chemicals and toxic metals linked to cancer, and lung and cardiovascular disease. Their use has also been linked to depression and anxiety—even as the tobacco industry aggressively markets addictive products to children and teens.

Researchers in the new study reviewed 52 systematic reviews of individual studies and four umbrella reviews published between 2016 and 2024, adjusting results for factors such as sex, age, socioeconomic status, and family or peer smoking.

Other key findings included:

• Vapers were three to six times more likely to use marijuana, four to more than six times more likely to drink alcohol, and over four to nearly seven times more likely to binge drink.
• Vaping was tied to a 20–36% higher risk of being diagnosed with asthma and a 44% higher risk of worsening symptoms. Coughing was also consistently associated with e-cigarette use.
• More than 50 cases of serious vaping-related lung injury (EVALI) were reported in patients as young as 13. Most involved e-liquids with tetrahydrocannabinol (THC), the ingredient in marijuana that creates the feeling of being “high.”

The new study also highlighted mental health and other impacts. Three reviews linked vaping to suicidal thoughts or behaviors, while six reported injuries, mainly from vape explosions. Others suggested potential links to pneumonia, bronchitis, reduced sperm counts, dizziness, headaches, migraines, and oral health problems such as dry mouth and gum bleeding.

“Our review provides the most comprehensive picture to date on the range of risks vaping poses to young people,” said Dr. Greg Hartwell, co-author and clinical assistant professor at the London School of Hygiene and Tropical Medicine. “In particular, we found consistent evidence around transitions to smoking which of course, in turn, opens the door to the multitude of harms that conventional cigarettes bring.”

Although smoking rates have fallen as vaping has risen, researchers noted declines are largely due to bans, taxes, and stricter sales and packaging rules. They found little evidence for the so-called “diversion effect,” which would mean vapers are less likely to smoke than non-vapers.

Addiction was largely absent from the reviews, yet most e-cigarettes contain nicotine, which is highly addictive. Another gap, the study noted, was how nicotine may affect adolescent brain development.

Much of the evidence beyond smoking risk came from cross-sectional studies, which make it harder to judge the long-term impacts, the researchers cautioned. They called for urgent, long-term studies on vaping’s effects on brain, heart, and oral health, as well as its dual use with cigarettes, and stronger protections for young people.

“Our findings support the implementation of policy measures to restrict sales and marketing of e-cigarettes to young people, and restrictions on advertising design features that are designed for, or likely to appeal to, young people,” the authors said. 

“Such efforts may form part of a wider set of measures to restrict harms, including raising the public’s and young people’s awareness of these harms, and counter-marketing to raise public and policy awareness of the marketing and strategies that e-cigarette companies have targeted at children and young people.”