Until this week, e-cigarettes had been sold without FDA regulation, and the companies making the devices have taken cues from separate regulations on tobacco products. On Tuesday, the Food and Drug Administration finally cleared the air.

In a final guidance, the agency laid out how e-cigarette makers should submit product applications to the FDA and guidelines for marketing and labelling of their products. It addresses many concerns the FDA and the public have expressed about e-cigarettes, including flavored pods, youth use and marketing and claims that e-cigs can help smokers quit.

Former FDA Commissioner Scott Gottlieb made regulating e-cigarettes and keeping the products out of teens’ hands a hallmark of his tenure. Gottlieb left the agency in April, but this guidance was a key part of his work.

Now that e-cigarettes must go through an FDA approval process, the agency has more control over how the products look and are marketed, a big step in keeping addictive products away from young people.

When it comes to the flavored pods or e-liquids, the FDA guidance recommends that e-cigarette applications detail consumer perceptions of flavors and look into the impact of flavors on current e-cig users, smokers and non-users. The agency is particularly concerned about the effect of flavors on youth and young adult perceptions in these applications.

Some e-cig companies such as Juul pulled flavored products off shelves in an effort to stem teen use and appease the FDA. These companies were worried that FDA might ban flavors entirely, like some cities have, but the guidance allows a path to make a case for selling flavored pods.

The guidance recommends that e-cigs should not make claims about smoking cessation unless approved as a drug or medical device. Because there are drugs and devices approved to help smokers quit, the FDA recommends that these companies submit their products to the Center for Drug Evaluation and Research or the Center for Devices and Radiological Health to make those claims.

Finally, marketing and labelling. The FDA has sent out dozens of warning letters this year alone for misbranding. The guidance lays out what warning information e-cig packages should include.

Their example: “WARNING: Contains nicotine, which can be poisonous. Avoid contact with skin and eyes. Do not drink. Keep out of reach of children and pets. In case of accidental contact, seek medical help.”

The guidance, while not a final rule, applies to all electronic nicotine-delivery systems sold to consumers, including both devices and e-liquid pods or refills.