WASHINGTON – The U.S. surgeon general on Thursday called the skyrocketing use of e-cigarettes among youth “a major public health concern,” saying that although more research needs to be done on its potential harms, policymakers should take strong action to keep the products out of the hands of the nation’s young people.

“We know enough right now to say that youth and young adults should not be using e-cigarettes or any other tobacco product, for that matter,” Surgeon General Vivek H. Murthy said in an interview. “The key bottom line here is that the science tells us the use of nicotine-containing products by youth, including e-cigarettes, is unsafe.”

E-cigarettes are the most commonly used form of tobacco among young people in the United States, having surpassed conventional cigarettes in 2014. Over the past five years, the number of middle- and high-school students who report having used e-cigarettes has tripled. Among young adults 18 to 24, the number has doubled.

Public health officials say that the sharp rise is troubling, in part, because of how much researchers don’t know about the long-term effects of “vaping.”

For example, although e-cigarettes are widely thought to contain fewer toxic substances than traditional cigarettes, scientists have shown that the vapor from e-cigarettes isn’t entirely harmless. In addition, although Thursday’s report stops short of saying e-cigarettes are a gateway to smoking, it found that vaping “is strongly associated with the use of other tobacco products among youth and young adults, particularly the use of combustible tobacco products.”

“A report of the surgeon general is the gold standard,” said Matthew L. Myers, president of the Campaign for Tobacco-Free Kids. “This doesn’t answer all the questions people have about e-cigarettes, but it provides a scientific base to guide policy decisions and future discussions. This report makes clear the importance of doing everything we can to decrease the use of e-cigarettes by young people and the need for regulation to accomplish that goal.”

Tobacco-control advocates and public health leaders say the popularity of e-cigarettes stems in part from aggressive marketing campaigns that borrow from the tobacco industry playbook of earlier generations. Thursday’sThe report echoes those concerns and calls for strict regulation of marketing aimed at young people.

E-cigarette firms have supported minimum age requirements for their products, and industry groups such as the Smoke-Free Alternatives Trade Association insist their members “have not and do not market to minors.” But public health officials say that not all manufacturers live up to that standard and have enticed young people with slick advertisements and an assortment of flavors from bubble gum to piña colada.

“Companies are promoting their products through television and radio advertisements that use celebrities, sexual content, and claims of independence to glamorize these addictive products,” Tom Frieden, director of the Centers for Disease Control and Prevention, wrote in a forward to the report.

Others suggest that some concerns may be misguided. “Although electronic cigarette uptake has skyrocketed among youth, cigarette smoking has fallen at historic rates,” said Michael Siegel, a tobacco-control researcher at Boston University’s School of Public Health.

“This would be nearly impossible to explain if electronic cigarettes were causing a substantial number of youths to start smoking,” Siegel, who had not seen the report, said in an email. “While the Surgeon General is rightfully concerned about the emergence of a vaping culture among young people, the truth is that this vaping culture is helping to displace a smoking culture. All in all, this is a good thing.”

The report focuses exclusively on the use of e-cigarettes among the young and steers clear of the broader public health questions surrounding what has become a $3.5 billion industry: Will vaping prove to help adults quit cigarette smoking and reduce tobacco-related deaths? Are e-cigarettes less harmful than cigarettes, as a growing body of research seems to suggest? Should e-cigarettes be regulated the same way as traditional tobacco products?

Such questions have raged for years, with no resolution in sight.

Murthy said the report didn’t aim to address those larger questions. Its primary purpose, he said, was to outline the clear risks of e-cigarettes to youth and to give parents, teachers and other adults guidance on how to prevent young people from using them.

“In order to address tobacco in America, we need a multipronged approach,” he said. “What’s at stake here is really protecting the next generation from nicotine addiction and tobacco-related disease.”

This spring, the federal government began regulating the booming e-cigarette market two years after it said it intended to do so. The regulations include a ban on the sale of e-cigarettes to anyone younger than 18. They also require manufacturers to disclose their ingredients and submit their products to the government for approval.