A man smokes an e-cigarrette and blows out the smoke at his stand at the InterTabac trade fair.

The Food and Drug Administration is considering banning online e-cigarette sales, Commissioner Scott Gottlieb said Tuesday.

It's "on the table" and is something the agency is "very clearly looking at it," Gottlieb said in Washington during a panel discussion on vaping hosted by Axios. This comes just weeks after Gottlieb dubbed youth use of e-cigarettes an "epidemic" and announced a historic crackdown.

Under Gottlieb, the FDA has taken the position that e-cigarettes are a less harmful alternative for adult smokers who can't or don't want to quit smoking conventional cigarettes. However, Gottlieb has said that can't come at the expense of addicting an entire new generation to nicotine as vaping rises in popularity with teens.

Over the past year, the number of high school students who have used e-cigarettes during the previous 30 days has skyrocketed by about 75 percent, preliminary data from the Centers for Disease Control and Prevention's annual National Youth Tobacco Survey show, according to people familiar with the data. They asked not to be identified because the report isn't yet public.

The FDA earlier this month ordered five nicotine vaping brands — Juul, British American Tobacco's Vuse, Altria's MarkTen, Imperial Brands' Blu E-cigs and Japan Tobacco's Logic — to submit plans within 60 days detailing how they will prevent teens from using their products. Gottlieb is threatening to pull flavored e-cigarettes off the market and even require manufacturers to submit them to the agency for review.