When vapes started to become popular in the mid-2010s, the tiny cartridges carried big promises. They were presented as a healthier alternative to cigarettes and a path to quit smoking.

Now, researchers are coming to understand the hazards of vapes themselves. In a study from last month, for example, a team of scientists analyzed the mist from popular vapes and found such high levels of heavy metals that one researcher thought their machine had malfunctioned. Other studies have suggested that vaping can affect the heart, lungs and brain.

Experts said they were worried that vaping may become harder to study after the Trump administration shut down a unit focused on smoking and health. The government has also slashed funds for programs that help people stop vaping.

Data on the long-term health effects is limited, because vapes are relatively new and constantly evolving. Many people who use them are in their teens or 20s; it might take a while before further effects become apparent. Consumers also often use both cigarettes and vapes, which makes it difficult to isolate harms from vaping alone. Vaping is still less common than cigarette use among U.S. adults, 4.5 percent of whom said they vaped in 2021. Nearly 8 percent of high school students reported vaping in the last month in a 2024 survey.

Even so, “common sense tells you — your mom would tell you — that a superheated chemical inhaling right into your lungs isn’t going to be good,” said Dr. James H. Stein, a professor of cardiovascular medicine at the University of Wisconsin School of Medicine. Increasingly, research is pointing to the reality that while vapes do not contain the same dangerous chemicals as cigarettes, they come with their own harms.

Cardiovascular Concerns

A hit from a vape immediately stresses the cardiovascular system. Your heart rate rises and your blood vessels constrict, which can stiffen arteries in the heart over time. When you vape “all day long, over and over and over again — you’re basically walking around with high blood pressure,” Dr. Stein said. These effects could raise the risk of developing an irregular heart rhythm, stroke and even a heart attack.