Juul Labs pre-empted the measures by ending social media promotion of its products and stopping in-store sales of its flavored pods, other than tobacco, mint and menthol. In September, the FDA gave e-cigarette makers 60 days to prove they weren't targeting minors with their marketing. The agency seized marketing documents from Juul during a surprise inspection last month.

"Almost all adult smokers started smoking when they were kids," FDA commissioner Scott Gottlieb said in a statement. "Today, we significantly advance our efforts to combat youth access and appeal with proposals that firmly and directly address the core of the epidemic: flavors. The data show that kids using e-cigarettes are going to be more likely to try combustible cigarettes later. "

The FDA is also attempting to ban menthol cigarettes and flavored cigars, though those proposals could take two years to pass regulatory hurdles. That ban would likely have a large impact on African-American smokers, who opt for such products at higher rates than other groups.