The Medical Minute: What’s in a vape? Even scientists aren’t sure

A quick cloud of vapor and the faint aroma of green apple may be all the evidence many young people leave behind as they vape. But while vaping may be easier to hide than traditional cigarette smoking, its health effects can be just as harmful. The 2025 National Youth Tobacco Survey found that roughly 1.4 million middle and high school students use nicotine vaping products.

Dr. Daniel Guck, a pulmonologist at Penn State Health Milton S. Hershey Medical Center, says vaping has many of the same health risks as smoking.

“Nicotine addiction comes with cardiovascular effects, with higher heart rates and blood pressure, and neurological effects, such as headaches,” Guck says. “Although we don’t yet have sufficient long-term evidence to establish a direct link between vaping and lung cancer, we have legitimate concerns about its potential long-term cancer risk.”

The American Lung Association warns that vaping exposes people to toxic chemicals that can damage lung cells, cause breathing problems and increase the risk of lung disease. Chronic cough, shortness of breath and wheezing are other potential effects of nicotine vaping.

Guck is particularly concerned about vaping’s popularity with young people in their teens and 20s.

“Big tobacco has shifted its focus from cigarettes for minors over to vaping,” he says. “While we’re seeing cigarette use drop significantly, vaping use is increasing in similar amounts.”

Unknown Ingredients Pose Real Risks

If this laundry list of health impacts isn’t enough to make people think twice about vaping, Guck says the unknown ingredients in vape pens should. While vaping eliminates the carcinogens produced by burning tobacco, the flavorings and other additives in e-cigarettes may also increase cancer risks.

“We know all the risks of cigarette smoking because it’s been around for decades, but with vaping, it’s relatively new in society, and regulation and enforcement haven’t kept pace with the rapidly changing vaping market,” he says. “What’s inside a blue raspberry flavor vape versus a plain nicotine vape? We don’t know the long-term health consequences from inhaling these chemicals.”

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How Vape Flavors Affect the Brain

Andrea Hobkirk, an associate professor of neuroscience and experimental therapeutics, public health sciences, and psychiatry and behavioral health at Penn State College of Medicine, is looking for the answers to these questions. She recently completed a pilot clinical trial to determine whether flavor additives like popular fruit flavors make vaping more addictive.

The study examined whether hexyl acetate, a flavor additive known to affect the nervous system, caused adults to vape more than a version without that additive. Participants were divided into two groups and sent home with different vaping products.

One group received a vape containing hexyl acetate, while the other received a control vape with ethyl acetate, which tastes similar, but has no known neurological effects. Researchers also used functional MRI scans before and after the trial to measure brain activity during vaping and see how participants responded to a computer task for a monetary reward.

After 10 days, they found that study participants who used hexyl acetate increased their vaping by 13 puffs a day, while the control group decreased by two puffs a day. Although the experimental vape group showed no increase in brain activity during vaping, the hexyl acetate group responded more to the online reward task than the control group.

Hobkirk says the findings suggest that certain flavor additives may affect the brain’s reward system in ways similar to nicotine.

“When people start using nicotine and become dependent on it, it makes them more responsive to rewards,” she says. “We’re seeing a similar effect here. They became more responsive with the neuroactive flavor.”

The findings raise more questions about what’s really inside vaping products.

“We don’t know the full effects of the flavor additives. Products are coming out now that have things like synthetic nicotine being sold as less addictive, but we don’t know what happens when you add it to a potentially addictive flavor chemical. Does it now make nicotine more addictive? We don’t know yet,” she says.

Explore clinical trials on vaping and smoking at Penn State College of Medicine.

Vape Regulation Falls Short

Keeping track of the many ingredients in each brand of vape is difficult, in part because of limited federal oversight and the wide range of products on the market. Logan Fox, a doctoral student at the Penn State Center for Research on Tobacco and Health, discovered thousands of different e-cigarettes being sold in the Penn State Health coverage area, even though only 48 e-cigarette products are federally authorized for sale.

“So much is being sold and have additives that nobody knows about,” Hobkirk says. “Researchers are trying to keep up with them, but the additives aren’t really being regulated or watched in any meaningful way.”

Despite the unknowns, vaping companies continue to market their products. Even celebrities aren’t immune to its lure and consequences. Singer and actress Selena Gomez recently highlighted another side effect of vaping: vocal changes.

“Nicotine is so hard to quit,” she shared in an Instagram story in October. “If you’re going through it or you’re even trying to vape, it’s just not worth it. It’s so stupid.”

The 2026 Great American Smokeout is Nov. 19. Learn how to quit vaping or smoking.

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• Nicotine e-cigarettes reduce harmful chemical exposure, help smokers quit
• The Medical Minute: Long-term smoker? Lung cancer screenings can save your life
• Video: How can I quit smoking?

The Medical Minute is a weekly health news feature produced by Penn State Health. Articles feature the expertise of faculty, physicians and staff, and are designed to offer timely, relevant health information of interest to a broad audience.

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